# Tangent Young-Jung power supply



## grenert

I see that Tangent has been working on a new power supply that appears to be a replacement for STEPS:
Young-Jung Power Supply

 I know he had some PCBs available for a while. Have any of you tried it out yet?


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## rds

I'm building one tomorrow. I'll post some pics.


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## TzeYang

One crucial question would be how much capacitance will this regulator drive stably?


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## n_maher

Did he finally put it into production? The design has been around for years now and as far as I know was never finished.

 I've had one going for ~2yrs now in my Millett Hybrid and also built one for my PPA years back which is still in service. One important thing rds, do yourself a favor and modify the pcb to allow you to bolt down the two large heat sinks. I had one snap off in transit. 
	

	
	
		
		

		
			





 For one of the sinks it's pretty easy, for the other you can only get a fastener on one side but that's still better than nothing. And if you have any questions just ask, I may or may not remember the answer but I can always just look at the board that I still have.


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## rds

Quote:


 if you have any questions just ask, I may or may not remember the answer but I can always just look at the board that I still have. 
 

Thanks Nate - I appreciate that.


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## tangent

Quote:


  Originally Posted by *TzeYang* /img/forum/go_quote.gif 
_how much capacitance will this regulator drive stably?_

 

I don't know where the limit is, but I have one powering a PPA that I use daily, which has never had a fault. I probably put nearly 2000 uF onto its rails.

  Quote:


  Originally Posted by *n_maher* 
_modify the pcb to allow you to bolt down the heat two large heat sinks_

 

Consider it done.

 There will be at least one more prototype run of this board, so now's the time to make requests.


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## n_maher

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_There will be at least one more prototype run of this board, so now's the time to make requests._

 

I believe that I mentioned this way back when I gave you my build notes but have you ruled out a Vout trimpot simliar to the STEPS design? Personally, I have no issue with the resistor setup the way that it is on the current pcb but the tweakers out there might not be happy until they can dial in exactly 24V out (or whatever). 
	

	
	
		
		

		
		
	


	




 One more thing for rds: watch out for the on board fuse location. I found that the spacing of the mounting points was a bit too close for the typical fuses. It might be easier to just use an off-board fuse if you have the same version pcb that I had. I know tangent was going to address it in future versions.


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## Mazuki

Can you space out the I/Os so that solderless terminal blocks can be installed?


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## JamesL

Quote:


  Originally Posted by *Tangent* 
_I made a small prototype run of YJPSes for early adopters, and am waiting to hear reports about how those are working. In the meantime, I'm working on an improved version. This will probably take a few months to result in boards en masse._

 

I wonder if the 'improved' version suggests changes to the board layout, or the schematics. To be honest, I wasn't too thrilled about the steps, but the improved regulator on the yjps looks really promising.


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## rds

Quote:


 I believe that I mentioned this way back when I gave you my build notes but have you ruled out a Vout trimpot simliar to the STEPS design? 
 

It looks like you can squeeze in a 1k trimpot at r11. I think that would do the trick


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## tangent

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I believe that I mentioned this way back when I gave you my build notes but have you ruled out a Vout trimpot simliar to the STEPS design?_

 

Yeah, I wasn't wild about it then, and I'm not wild about it now.

 I think it's because it goes against my concept of a precision DC power supply. Making it adjustable will make the feedback loop larger, and it implies that the output won't be exactly as-designed, within component tolerances. I guess I could talk myself into a very small trim pot that adds to one of the two fixed Rs for compensating for those component tolerances, but then you risk drift. Ech...

 My opinion on this isn't set in stone...this's just what I think right now. 
	

	
	
		
		

		
		
	


	




  Quote:


 I found that the spacing of the mounting points was a bit too close for the typical fuses. 
 

I'll look at it.

  Quote:


 It might be easier to just use an off-board fuse if you have the same version pcb that I had. I know tangent was going to address it in future versions. 
 

The ones that went out recently were v1.0. Maybe you could crack the case on yours to see if it was, perhaps, 0.5 or even 0.4?

  Quote:


  Originally Posted by *Mazuki* /img/forum/go_quote.gif 
_Can you space out the I/Os so that solderless terminal blocks can be installed?_

 

Already on the Wishlist, definitely to be done in the next version.

 While on the topic, here's the current Wishlist:

Move secondary-side parts farther away from primary, 8mm minimum distance
Make it possible to parallel transformer outputs. (Not helpful with 15 or 25 VA, but will let you use 5-10 VA transformers, when lower supply voltages are allowed.)
Move C8 out from between output pads, to allow use of terminal block
Add extra GND pad(s)
Add silkscreen labels to board to make use of unencapsulated toroids easier
Bigger X and Y cap positions than STEPS
Add holes for heat sink mounting screws
Double-check fuse clip distance

 Any type in particular you want to use? I had in mind Molex KK's.

  Quote:


  Originally Posted by *JamesL* /img/forum/go_quote.gif 
_I wonder if the 'improved' version suggests changes to the board layout, or the schematics._

 

Anything concrete?


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## rds

Do the schematic R values give a 30 Volt output?

 EDIT - so it looks like the stock values of r11 = 1k and r10 = 1.2k give 15 volts. It also looks like the ad825 can't output more than 30 volts. r11 = 1k and r10 = 3.3k will do 29.8volts. Bad idea?


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## tangent

D3 zeners in normal operation, so it should work fine when set at 30V.


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## TzeYang

there's something i don't understand about the schematic.

 Where does the collectors of Q3 and Q4 connect to? The positive rail?


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## tangent

Heh, heh. They don't connect anywhere.

 I could tell you what they're doing, but this is a good EE puzzle. (Hint: AoE, page 62.)


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## TzeYang

lawlz, they're acting as diodes.

 EDIT: Oh wait, you could just use regular diodes like 1N4148, why use the transistors?


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## tangent

Small-signal transistors acting as diodes are less leaky than generic diodes. That's valuable here because they're supposed to be reverse-biased under all normal conditions. I suppose there must be a trade-off...lower maximum forward current, perhaps?


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## rds

How critical are the values of c10 and c8?
 I'm looking at using 150uF 35v caps for c7-c11. I'm just a little iffy on c10 and c8.


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## JamesL

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Anything concrete?_

 

Sorry, concrete? I was just wondering what you meant by an improved design.. 
 It sounded like you had something on mind that you were working on.


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## tangent

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_How critical are the values of c10 and c8?_

 

Not very. I'd go smaller rather than larger. The main thing is to use caps with the expected case sizes, so they sit down properly on the board.

  Quote:


  Originally Posted by *JamesL* /img/forum/go_quote.gif 
_I was just wondering what you meant by an improved design._

 

Oh. Well, all the Wishlist items above will get done before the next version. Between v1.0 and now, I have:

Renamed Q3 and Q4 to be in D series, to hopefully avoid more confusion on this topic
Made the test point holes bigger, to allow Keystone wire loops
Moved diodes and associated caps farther away from the board edge
Added DO-201 pads around TO-220 bridge diode pads, as in STEPS v1.2
Fixed spacing between D1 and its bypass cap

 Relative to STEPS v1.2, obviously the regulator is a vast improvement. I've also gone back to the big 6-pin line chokes I used back the STEPS 1.0 days -- I've got the space again.

 I'm dithering on whether to nix the 35 VA transformer option. Unless you change the CCS biasing, the circuit as designed can only put out about 330 mA, so there's no way to actually pull that much power from this supply. Even 25 VA is overkill, but the recommended Talemas use the same pin spacing for them as for the 15 VA ones. 15 VA is plenty big for this.

 What's staying my hand from deleting the 35 VA option is that other manufacturer's transformers may not be as compact, and it's nice to have even a thin excuse to keep parts away from the transformer. I'll probably only nix it if I actually need the room again.


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## TzeYang

How much current that the regulator can handle is dependent on the quality of the pass transistor?

 EDIT: Knowing that the super regulator design exists, I wondered why Amb went with a much more traditional sulzer like basic discrete regulator (Sigma 11) instead of following to something similar like Walt Jung's super regulator design


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## rds

A hole for 7.5mm diode caps would be nice.


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## 1UP

Hi - is this a dual supply? What would be the main differences between this and the Sigma 22?


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## amb

Quote:


  Originally Posted by *TzeYang* /img/forum/go_quote.gif 
_EDIT: Knowing that the super regulator design exists, I wondered why Amb went with a much more traditional sulzer like basic discrete regulator (Sigma 11) instead of following to something similar like Walt Jung's super regulator design_

 

Not to thread-crap, but σ11 is the single rail rendition of the σ22, and you should read the headwize thread which discusses the thoughts behind the design. An all-discrete circuit with high output current capability was a requirement from the onset. IC-based solutions would have been impossible to meet all of the original design goals stated in the thread.

 Btw, compare Erno Borbely's EB703/259 PSU to σ22. Borbely's PSU isn't auto-tracking like the σ22, but there are some topological similarities.


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## tangent

Quote:


  Originally Posted by *TzeYang* /img/forum/go_quote.gif 
_How much current that the regulator can handle is dependent on the quality of the pass transistor?_

 

No, the limit on output current is set by the CCS that keeps the pass transistor "open". (D2, R5, R6, Q1) The maximum output current is that CCS value (~5.5 mA) multiplied by the pass transistor's hFE. The 330 mA number I gave above is actually the minimum output current, being calculated with the minimum hFE for a D44H11. You can lower the R6 value to increase the current limit, but you don't want to make it any bigger than you have to, because the error amp has to sink away all of this current when there is no load on the regulator. The less current the error amp has to sink away, the better it will perform.

 Anyone interested in how this regulator works should first read my Op-Amp Based Linear Regulators article, which introduces the concepts behind this piece by piece. To dive deeper, there are links at the end of that article to the original Jung articles.


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## rds

I can't figure out how you fit the ELF850T on the board. Did you move the pins?


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## tangent

I'm not sure I understand the question.

 Are you saying that the part you bought doesn't fit on the board? If so, can you take a picture to show it?

 Or are you asking how I managed to get back to the larger filter choke? The answer there is, it's a bigger board than the STEPS, so I had more room.


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## rds

My ELF850T has 6 pins with wider spacing than the 4 pins provided on the pcb. I ordered the one listed in the parts guide afaik.
 Maybe there are different pin versions of the ELF850T?


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## tangent

Crap....I misunderstood my own notes. The YJPS 1.0 boards are using the same chokes as STEPS 1.2, not STEPS 1.0!

 You can adapt the choke you have to the board. The middle two pins are just for stability. Just match the outer 4 pins on the choke to the 4 pads on the board. You'll have to rig some way to keep it stable if you'll ever subject the joints to stress...ship it, travel with it, etc.

 I'll be fixing this for the next version of YJPS. The space _is_ there for the bigger choke.


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## error401

Mentioned it in the other thread, just a quick note here...

 The transistors aren't listed in the parts guide. Doesn't seem to make sense for that to be intentional...


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## rds

It looks like the guide still needs some work. I don't think C8-c12 are mentioned either. You need to refer to the schematic directly at this point.


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## rds

I'm planning to use this for C1:
Digi-Key - P11006-ND (Panasonic - ECG - ECQ-U2A124ML)
 and these for C2:
Digi-Key - P4608-ND (Panasonic - ECG - ECQ-U2A472MF)

 These seem to be appropriate caps. Am I missing anything?


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## n_maher

I'd have to look more closely at those parts and the schematic but what I did was reference back to the equivalent part on the STEPS project when it seemed appropriate. Maybe that's what you're doing, but I'm at work and can't tell for sure. If not, look to STEPS for confirmation since the pre-reg stage is pretty similar IIRC.

 [edit]The pre-reg stage of the YJPS is essentially the same so for C1 you want something like part # P10730 and for C2 #P10992.


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## rds

Yeah, I have looked at the requirements and it's really c2 I want confirmation on. My understanding is it is type Y and rated for 250 V AC power line. But since I haven't seen them used before in STEPS I want to confirm I'm not overlooking something.


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## tangent

Yes, the line filter caps are the same in YJPS as in STEPS.

 Basically, the gaps in the current YJPS docs are just in areas where I don't think there are any surprises.


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## rds

I'm getting 7.7V regulated. The only value I've change is r10 to 3.32k.
 I'm getting no voltage drop across d6, so obviously that's a problem. Can't figure out why... yet.
 Is there supposed to be a jumper from rsv to rsvj?


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## error401

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I guess I'm missing something here, but when the r3 and r4 values in the schematic set the lm317 output to ~10V how are you supposed to get above 10v output? The build guide recommends not changing r3 and r4. I'm trying to get 30V output and my r10 and r11 values are 3.32k and 1k respectively. 
 As I would have expected I get about 7.7V regulated since the 317 is putting out 10v. Should I just ignore the instructions not to change r3 and r4?

 EDIT it seems having about 2.5k on r4 would fix things. Does that sound right?_

 

The LM317 floats above the regulator output voltage. As you can see in the schematic, ADJ is connected to Vout rather than ground as would normally be used. As written, the schematic keeps the LM317's output at ~2.3V above the regulated output at all times. This is the design mentioned by Jung in the 'Improved Positive/Negative Regulators' article on his site. It also appears in the National LM317 datasheet in the 'typical applications' section as a 'tracking preregulator'.

 Because the prereg tracks the output, there's no need to adjust the resistors, it will always be 2.3V above the output, which gives enough headroom for the pass device to do its job.


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## rds

Thanks error401, I went back I figured this out. Now it seems the issue is that I need to jumper rsvj and rsv as well as rscg and rsrg. Sound right?


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## error401

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Thanks error401, I went back I figured this out. Now it seems the issue is that I need to jumper rsvj and rsv as well as rscg and rsrg. Sound right?_

 

Yes. RSV and RSRG are the sense network input and ground respectively. The Jung design allows remote sensing, so if you wanted to you could connect RSV to the output at the load, and RSRG to the ground at the load. This lets the regulator compensate for lead impedance and so on. Jumpering them just connects the sense network directly at the regulator, as with most regulators you're probably familiar with.

 Note: I'm going by the schematic here, I don't have one of these particular boards/designs built up.


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## n_maher

Quote:


  Originally Posted by *error401* /img/forum/go_quote.gif 
_Note: I'm going by the schematic here, I don't have one of these particular boards/designs built up._

 

Sure sounds right to me and looks to be how I've got mine configured.


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## rds

Ok, thanks guys. I'll jumper those points. If you don't see me around again, then you know this is in fact not the right way to do it.


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## n_maher

If you're worried I'll pull mine tomorrow and photograph it for you. I can't see the jumpers on the bottom so I can't confirm 100% for you.


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## rds

Thanks Nate - everything seems good. 





 But if you do confirm that your jumpers are the same I'd appreciate it.
*Also, another wish list board change is making Vout a larger diameter.*


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## kipman725

I found your previous collection of articles on the super regulator and notes quite interesting tangent. How does it compare with high end lab supplies etc for its noise?

 *is it at the point where to further reduce supply noise would be running up against physical limits such as Johnson noise?


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## tangent

If we believe my 0.007 mV measurement, that's about 22 nV/rt.Hz over the measurement bandwidth of an LNMP. That's about equivalent to a 30K resistor. Pretty decent, considering how many parts are in the regulator.


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## 00940

I just had a look at the schematic. Why is the output cap (C11) (and way less importantly the led D7) connected to the sense ground (RGND) ? In Jung's articles, it's connected to the "dirty" ground (CGND).

 Maybe I missed it, but I couldn't find a pic of the board layout ?


 I must confess (sorry for being blunt) that the idea of spending a fair amount of money to get the lowest possible output impedance and then throw it away by putting the regulator far away of the powered circuit (and throwing connectors into the mix) is looking a bit strange to me. AOS or ALW way of making the reg as small as possible to put it very near of the amp attracts me more.


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## error401

Quote:


  Originally Posted by *00940* /img/forum/go_quote.gif 
_I must confess (sorry for being blunt) that the idea of spending a fair amount of money to get the lowest possible output impedance and then throw it away by putting the regulator far away of the powered circuit (and throwing connectors into the mix) is looking a bit strange to me. AOS or ALW way of making the reg as small as possible to put it very near of the amp attracts me more._

 

I think that making use of the remote sensing should negate the effects, but I have to agree. Regulators really belong with the components they're powering, though I can't argue with an external preregulator to keep as much 60Hz as possible away from the audio.


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## 00940

You're of course right, remote sensing should negate the bad effects of long wires... if it doesn't throw the regulator into oscillation. With an oscillator, it can be checked. Without one, I'd stay away of remote sensing in the case of a two-boxes system.


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## n_maher

Just in case anyone was interested in using one of these in a project, there's one listed in the FS forums.


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## funch

Soooooo ...... whatever happened to this PS? Still under development, or 
 DOA?


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## rds

I hope it is being made available. It is very nice.


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## tangent

I was waiting for those who got the v1.0 boards to give some feedback. *Crickets*

 I guess silence is an answer, of a sort, to the question, "does it work?"


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## rds

It worked great for me. No issues with the performance at all.
 If the wish list requests from this thread were implemented then I think it would be completely ready for a production run.


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## rds

Any news on the YJPS production boards?


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## espressogeek

Yea I have been considering one , well, just to have.  Another option was the omega 11, I think that is what it is called.


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## tangent

I've been interleaving v1.1 work with other stuff I have going. It's nearly done, but progress is slow because I don't get back to it very often. I'll try to get it done this weekend.

 EDIT: v1.1 will be another proto run, because so many things have changed. If v1.1 works, v1.2 will be the production run.


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## qwerty870

I'll get a couple whenever they become available.


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## tangent

Finally (!) I have something I'm willing to present in public again. Schematic and board layout:





 (Click board to see larger version.)

 Changes since v1.0:

 - Diode bridge and transformer are farther away from the board edge.

 - Added a third unregulated filter cap

 - Line filter choke can now be the big ELF 850 series I used on the first versions of the STEPS, or you can use the inner four holes for the same chokes as were used on STEPS v1.2. Larger board allows this while still keeping plenty of space between the primary and secondary sides of the supply.

 - Line filter caps have more space around them than on STEPS. I have some caps here that have the right specs but don't fit on the STEPS, so this fixes that.

 - Unlike on STEPS, you can now parallel the secondaries on the transformer, not just the primaries.

 - Transformer pads are labelled now, to make it easier to use wire-leaded toroids

 - Still plenty of breathing space around the transformer. I briefly played with allowing 35 VA transformers, but on running the numbers, there's actually no way to use that much power with this design. Removing that allowed me to move the transformer closer to the upper board edge, away from the diode bridge and filter caps.

 - Moved fuse clips farther apart to allow use of the type with ears. (I fixed this on the STEPS long ago, but was in the YJPS v1.0 because it was forked from the STEPS design before the fix.)

 - Heat sinks have mounting holes and better outlines

 - Changed board mounting holes so they have explicit clearance around them for bolt heads

 - Output pads now use a Molex KK footprint instead of wirepads.

 - Output voltage is now adjustable, with the default schematic values giving a 18 to 30 V range, centered on 24 V. (I yield, I yield!)

 - Remote sensing pads now shown on the board and schematic as jumpers, to make it clear that they need to be connected somehow, whether it's by an actual jumper or at the circuit being powered to get remote sensing.

 - Split the unregulated section of the ground plane away from the control section, so one can play with decoupling them with a small resistor or inductor.

 - Test points allow larger wire loop test points. (This may change again.)

 - Most of the test points collected together at the board edge now, rather than scattered around the board.

 - Various part name changes (just to say, don't go comparing old docs and schematics to the board and expect things have stayed the same)

 I'm allowing some time for public comment and for me to sleep on the recent changes before I send this off for prototyping. I may do it on Monday, but no promises.


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## MASantos

Tangent, I can't see the image you posted above. Do other members see it?


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## n_maher

Here's the image, Tangent's url just got cut off.


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## DaMnEd

Quote:


  Originally Posted by *MASantos* /img/forum/go_quote.gif 
_Tangent, I can't see the image you posted above. Do other members see it?_

 

http://tangentsoft.net/elec/yjps/bitmaps/board-1.1.png

 EDIT
*n_maher* got it first


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## tangent

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Tangent's url just got cut off._

 

No, tangent just proved to himself that he still does occasionally post a URL publicly that points to his private web server.


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## error401

Just a random idea...

 I wonder if it might be useful to include a spot for a current sensing resistor before the output. Would be very handy for testing amps.


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## tangent

The point of this supply over something more typical is extremely low output impedance. You can't put a resistor on the output directly, or you'll wreck that. You could work out some kind of jumper scheme, but even that adds more resistance to the output.

 If you install a Molex KK connector on the output, you can rig up an alternate version with such an inline resistor, or simply break the circuit with it so you can insert an ammeter.


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## tangent

Gerbers away.


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## tangent




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## fran

Tangent: will you be offering a kit for this (as opposed to the boards only) and also, will it be possible to do a dual rail supply with it?

 Fran


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## tangent

Quote:


  Originally Posted by *fran* /img/forum/go_quote.gif 
_will you be offering a kit for this_

 

Sorry, no. Too many parts, many of them expensive. I wouldn't have a problem selecting a set of parts, but the expense and difficulty of kitting them in a sane fashion...<shudder>...

  Quote:


 will it be possible to do a dual rail supply with it? 
 

Sure, but it would be inefficient. You'd end up with at least two YJPS boards, and either one or two transformers, depending on how you want to work that. If that's your goal, I think you'd be better off going with one of the small transformer-less Jung regulator boards that already exist.

 And no, there won't ever be an inherently "dual" version of the YJPS, with everything on a single board. It's not my niche.


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## grenert

Those are pretty impressive numbers on that sheet of paper...


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## tangent

Yes, that's rather the point of showing them. 
	

	
	
		
		

		
		
	


	




 I especially like the fact that the regulated output value didn't change at all when going from no load to a 105 mA load.

 I haven't yet done LNMP testing, this is just my raw DMM readings. (My LNMP is broken at the moment. Grrr.)


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## schubert

I hope an application question is OK here, even though this seems to be mostly a design thread. I need a new power supply for my Sota turntable - would the Young-Jung supply be appropriate for this use? Some details - my current supply puts out 25VDC (no regulation) and the motor momentarily draws around 150 mA while accelerating (occasionally up to 220 mA) and then settles to less than 50 mA. I'm looking for a lower cost high-performance alternative to Sota's "electronic flywheel", which is $300. 

 Thanks!


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## tangent

I don't see why this wouldn't work, but then, I've never built or even modded a turntable.


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## schubert

OK thanks Tangent, I'll go ahead. And thanks in general for all your work on the PPA etc - I built a PPA and a STEPS and I love them!


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## espressogeek

I have a question about the filter that precedes the toroid in the schematic. Can this filter be applied to any electronic device's power supply?


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## error401

Quote:


  Originally Posted by *espressogeek* /img/forum/go_quote.gif 
_I have a question about the filter that precedes the toroid in the schematic. Can this filter be applied to any electronic device's power supply?_

 

It's basically identical to the circuit used in inexpensive line filters (e.g. http://www.cor.com/pdf/K.pdf), but with a beefier choke. You can use it for any circuit, provided you observe part ratings. Make sure you use line-rated components (C1 must be class X, C2 class Y) for safety.


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## espressogeek

Thanks error401!


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## TimmyMac

Interesting... I'll definitely be up for a couple boards. Would this thing be good for running down in the DAC power supply range? 1-5V? I've got a TREAD and a protoboard'ed STEPS ready for the DAC I'm building, but I wouldn't mind trying something a little nicer...

 As a side note, would an RC filter (something like 10-20ohms) on the output of a TREAD/STEPS get a bit more ripple rejection? Would it be worth it, or a waste of time?


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## tangent

Quote:


  Originally Posted by *TimmyMac* /img/forum/go_quote.gif 
_Would this thing be good for running down in the DAC power supply range? 1-5V?_

 

Getting down to 2.5V isn't a problem. Below that, you might have to get tricky. Basically, you replace the voltage reference with a lower voltage one, and there are readily available ones in this package and pinout down to 2.5V. There are lower voltage references, and alternatives to this sort of reference that go below 2.5V, but I don't know that they fit the footprint.

 EDIT: You'll probably also have to change the AD825 out for a chip that's happier on lower supply voltages.

 EDIT2: Ditto D3. I've modified the YJPS part selection guide to discuss the D3 and U2 changes, and to cover the effect of changing D4 more clearly.

  Quote:


 I've got a TREAD and a protoboard'ed STEPS ready for the DAC I'm building, but I wouldn't mind trying something a little nicer... 
 

This should be especially good for a precision mixed signal circuit, due to the wide regulation bandwidth and the AC line filter.

  Quote:


 would an RC filter (something like 10-20ohms) on the output of a TREAD/STEPS get a bit more ripple rejection? 
 

Yes, if your only goal is to power a multimeter's measurement input terminals. Or *maybe* a true class A device. As soon as you put any kind of varying load on it, you get varying V drop across the R, giving ripple, probably far more than you are trying to fix.

 This is why we take so many pains to lower the output impedance. The ideal power supply has 0 ohms output impedance from DC to daylight.


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## schubert

My YJPS went together easily, but the regulator isn't working - I'm getting around 48-49 volts before and after the regulator. Voltages up to the regulator are fine. Can anyone help? I'm relatively new at this, and this is the first time I've really been stumped. 
	

	
	
		
		

		
			





 More details:

*1.* D4 gets hot (I'm not sure about the op-amp - I don't want to stick my finger down there! I'll use a digital thermometer when I get back to work)
*2.* Other voltages to ground (VSET at 482 ohms, no load): 





> a. between R8, R9 and D4: 7.0V
> b. between R8 and opamp pin 3: 12.0V
> c. between R10 and R11 (opamp pin 2): 12.8V
> d. between R11 and VSET: 6.4V
> ...


*3.* Adjusting VSET does not affect the output voltage appreciably. 
*4.* D2 lights momentarily when the unit is powered and then shuts off. With no load I thought this would be normal but I wasn't sure.

 Thanks in advance to anyone who can help!

 Here are some pics:
Attachment 12113

Attachment 12115

Attachment 12117

Attachment 12119

Attachment 12121


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_I'm getting around 48-49 volts before and after the regulator._

 

First off, that's going to be a very inefficient power supply even once you do get it working. Did you not use the power supply parameter estimator to choose the transformer? It would have predicted this. It doesn't yet go out and tell you that this is hugely wasteful, it just tells you what the voltage drop is, and assumes you know this is bad.

 If the estimator says the configuration is "sane," that means it can be made to work, not necessarily easily, but it's at least possible.

 If you're willing to accept 18-20 V regulated out of this, you can fix the efficiency problem by paralleling the transformer secondaries instead of putting them in series. Your alternatives are to either cope with the heat it generates (possibly requiring forced-air cooling when enclosed) or swap the transformer, which would be difficult.

  Quote:


 I'm not sure about the op-amp 
 

It's almost certainly dead, due to having 49 V across its rails. If not dead, at least damaged.

 The only question is whether this is whether this is the chicken or the egg. If the op-amp died while the regulator was still working, the resulting high voltage came afterward. If the high voltage is no fault of the op-amp, that killed it, so it could no longer force the regulator back to a normal output voltage.

  Quote:


 I don't want to stick my finger down there! 
 

You're going to have to stick something down there. It's going to have to be replaced. 

 Before you do that, check to be sure it wasn't installed backwards, and that you used the right sort of chip. Either error would explain the symptoms.

 Also, a useful test will be to just remove the op-amp and re-test. If the op-amp was the source of the problem, your build will turn into an overly expensive unregulated supply: you'll see the expected ~2.5 V drop across the preregulator, and D2 will stay lit up. It should be possible to power at least a light load with it, though unless you also parallel the secondaries, you may have some trouble finding a circuit it won't fry due to the high voltage it's putting out.

 If you try this and either the preregulator doesn't appear to be working or D2 won't stay lit, you have a different problem. You need to find and fix that before replacing the op-amp, or it'll get killed again as soon as you apply power.

  Quote:


 D4 gets hot...between R8, R9 and D4: 7.0V 
 

D4 is fine. You should be seeing about a 55°F rise over ambient. It's enough to make you take your finger back off it PDQ even when ambient is room temp, but not enough to hurt the IC, unless you put it into a hot enclosure. (See above.)

 The D4 temp will drop a lot when the regulator starts working.

  Quote:


 between R8 and opamp pin 3: 12.0V
 between R10 and R11 (opamp pin 2): 12.8V 
 

That's probably just Q3/Q4 doing their jobs, trying to clamp the +/-IN difference to a sane value. They should be getting warm, which is expected and harmless.

  Quote:


 between R11 and VSET: 6.4V 
 

That's very weird. I would expect about 9V across VSET in your current situation. The voltage across R10+R11+VSET is 49 V, which puts about 19 mA through here. Another 9V or so should be across R11, and the rest -- around 30 V -- should be across R10.

 I can't see JRSV in your pictures: is it jumpered? If not, that would explain a lot of problems.

 Is there a ~2.5 Vdc drop across the preregulator? (TP4 to TP5) If not, the preregulator isn't working, which could have fried the error amp at least, disabling the regulator, so would be the actual problem.

 Can you post a picture of the solder side?

 Speaking of pictures, the biggest thing you can do to improve them is turn on more lights, open the blinds, or take it outside to use the big bright day-ball for illumination. In the one set of EXIF data I looked at, the flash fired, the aperture was wide open, and it still managed only a bare-minimum 1/60s exposure. All of this says you didn't give the camera enough light to work with, which is why depth of field is so shallow.


----------



## schubert

Well now I'm completely embarrassed. I did not use the power supply parameter estimator - it was neglect and lack of thoroughness on my part. I'll make use of it once I figure it out and try to find a more appropriate transformer. I'll also have to assume that when you say that it is "nearly impossible to remove a PC mount transformer from the board once it’s soldered down without damaging the board" that you don't mean that it is completely impossible!

 To clarify, I'm actually after a 30V supply to use with a PPA v.2. I realize VSET is set wrong for this (I had been adjusting it to see if I could change the output voltage) - 482 ohms is just where it happened to be when I measured the voltages. If I understand your reply correctly, the transformer I have is still not ideal.

 Let me see if I have this right - I should look for a transformer that will give me around 32.3V DC between TP3 and TP5 instead of the ~51V I get with this one. Roughly speaking, that means a ±10V transformer wired in series (or ±20V in parallel) - does that sound right? I'll figure out the estimator and use it before I make a final decision.

 Other details:
*1.* JRSV is jumpered
*2.* The opamp (AD825) is installed in the right direction (I double and triple checked before I installed it - the little circle by pin 1 is over the small silver dot on the board), all the connections are good, and there are no solder bridges.
*3.* Voltage between TP4 and TP5 is 1.6V - should it be 2.5 volts now, or just when the opamp is removed? 
*4.* I remeasured the voltages around R10, R11 and VSET. They're a little different because I'm now in a different location, so the wall voltage is probably a little different. 





> TP3 to TP6: 47.9V





> TP3 to opamp pin 2 (between R10 and R11): 12.6V





> TP3 to between R11 and VSET: 6.3V





> TP6 to pamp pin 2: 35.1V


That gives about 9mA heading toward the opamp (?!)
*5.* Pic of solder side (sorry about the quality of the other pics - I hope this is a little better)
Attachment 12245
*6.* D2 lights up and turns off abruptly every time I plug in the unit - is it possible there is protection circuitry in the AD825 and it's just shutting down? If it was fried, wouldn't D2 cease to light up at all? I'm hesitant to remove the opamp until I'm sure I have to, since it's pretty cramped in there now. (I was only reluctant to stick my finger down there when it was powered up!)

 Thanks for your help - it is much appreciated.


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_I did not use the power supply parameter estimator_

 

Well, the bright side is that it's better now than before I wrote the previous post. I'd been meaning to add more warnings to it about obviously-wrong configurations, because experience has proven them to be non-obvious.

  Quote:


 I'll also have to assume that when you say that it is "nearly impossible to remove a PC mount transformer from the board once it’s soldered down without damaging the board" that you don't mean that it is completely impossible! 
 

True. I've done it once, and it's not fun at all.

 Ideally, what you'd want is to get four DIY friends to come over, set the YJPS upside down on a table, build up a solder blob to connect each pair of pins in the corners of the transformer so one iron can heat both pins at once through the blob, then have everyone apply their irons while one of you gently wiggles the transformer from below to get it to drop out of the board once all 8 joints turn liquid. Then you owe them beer.

 When you have to do it solo, you do much the same thing, only you dip your iron rapidly into the solder puddle, then go to another corner on the same edge, then back until you can get those two heated up. Meanwhile, you've got a small screwdriver under that same edge of the transformer gently prying up. Once you raise it by about half a millimeter, you transfer your efforts to the opposite edge. Half mm by half mm, you eventually lever the thing up out of the board. Then you drink lots of beer.

  Quote:


 I'm actually after a 30V supply to use with a PPA v.2. 
 

There's nothing magic about the 24 V and 30 V numbers you see tossed around here so frequently. A PPA will run on 20 V just as well. There may be some slight loss of sound quality, but that may be a tradeoff worth taking to avoid the desoldering challenge, and corresponding risk of cracking or removing PCB traces.

  Quote:


 I realize VSET is set wrong for this 
 

No, it's just that while the circuit is damaged like this, it can't affect the output voltage. It's useless.

  Quote:


 If I understand your reply correctly, the transformer I have is still not ideal. 
 

Sort of. You have _two_ problems. One is a broken regulator or preregulator circuit. (Exact fault and fix still to be determined.) 
 The other is an inefficient transformer configuration, which can be fixed two ways: replace it with a more appropriate transformer, or parallel its outputs and accept a lower output voltage, in the 20 V neighborhood.

  Quote:


 Let me see if I have this right - I should look for a transformer that will give me around 32.3V DC between TP3 and TP5 instead of the ~51V I get with this one. Roughly speaking, that means a ±10V transformer wired in series (or ±20V in parallel) - does that sound right? 
 

Just let the estimator guide you. Transformers and unregulated power supplies have enough weirdness in their behaviors that you don't want to try to figure out what they're going to do on the back of a napkin. That's why the estimator exists: so you don't have to try and work it out on paper.

  Quote:


 The opamp (AD825) is installed in the right direction (I double and triple checked before I installed it - the little circle by pin 1 is over the small silver dot on the board) 
 

Just checking...pin 1 is indicated on the AD825 by....?

  Quote:


 Voltage between TP4 and TP5 is 1.6V - should it be 2.5 volts now, or just when the opamp is removed? 
 

It should be ~2.3 V all the time. This suggests the LM317 may be dead. That would explain everything.

 Removing the op-amp before making that determination is still a good thing to do, however, because it's possible that a broken op-amp could jerk the LM317 around enough to cause problems here.

  Quote:





> TP3 to TP6: 47.9V





> TP3 to opamp pin 2 (between R10 and R11): 12.6V





> TP3 to between R11 and VSET: 6.3V





> TP6 to pamp pin 2: 35.1V


That gives about 9mA heading toward the opamp (?!) 
 

It occurs to me that it probably makes no sense to make decisions about what you see here while Q3 and Q4 are conducting. If you did want to check the sanity here, you'd remove the op-amp and temporarily lift one end of either R8 or R9. That will get the transistors out of the circuit so the divider just acts as a divider.

  Quote:


 Pic of solder side (sorry about the quality of the other pics - I hope this is a little better) 
 

I don't see anything seriously wrong with the soldering, though I could wish for better resolution and less JPEG compression... There's one blobby joint over near the right, but it's probably harmless.

  Quote:


 D2 lights up and turns off abruptly every time I plug in the unit - is it possible there is protection circuitry in the AD825 and it's just shutting down? 
 

The protection circuitry in an op-amp is connected to the input and output pins, not the power pins. The datasheet says the absolute maximum voltage you should put across this chip's power pins is 36 V. You've exceeded that maximum by 36%, repeatedly, and probably for a considerable amount of time each time.

 Is it possible for the chip to live through this? Sure. Sometimes people who get hit by lightning live to tell about it, too.

 If you're looking for something easy to remove as a first step, you can replace the LM317, too. But, if you suddenly start getting ~2.3V from TP4 to TP5, you still have a trust problem with that op-amp: why would you believe it's unharmed? It's not like the op-amp is anything other than the single most important component on the board...

  Quote:


 it's pretty cramped in there now 
 

I'd remove C11 and R12 so you can get at it.

 Then when replacing R12, put a properly-sized resistor in there. This is just the LED current-limiting resistor...there's no call to use a Vishay-Dale here. Any old carbon resistor will suffice.

  Quote:


 I was only reluctant to stick my finger down there when it was powered up! 
 

As you should be. 49 V is enough to kill humans.


----------



## n_maher

Finally got around to casing up my YJPS which will power an M3.


----------



## schubert

I used the estimator and found a couple of 2x12V transformers that will work, so I'll have a crack at taking this one out (hopefully not cracking the board in the process!). I'll order a new opamp and LM317 at the same time.

 I'll probably replace the transformer before I remove the opamp, since I don't really want to make do with the current transformer and I am clinging (irrationally?) to the hope that the opamp may be OK after all. If I get the new transformer in there and the numbers still aren't right, then I'll remove the opamp and test the voltage drop over the LM317 and replace it if it isn't 2.3V or so.

 Determining pin 1: As far as I can determine from the data sheet, the AD825 has a small circle of a different texture on the plastic case near pin 1 - that's right, isn't it? I think all of the opamps I've used so far are that way.

 I just used the Vishay-Dale for the current limiting resistor because I happened to have an extra one, that's all. I've used Radio Shack carbon resistors in the past but I ran out.

 I'd rather have a 30V supply, because that's what I was using previously with the PPA and I liked it. I'll probably be able to reuse the 70053 transformer in something else - in fact, do you have any STEPS boards left? I wouldn't mind building another one of those. I used 70053 in the one I built earlier and it works nicely.

 Thanks again for your help, Tangent. I'll post again once I get the new transformer mounted.


----------



## schubert

The transformer is off, and it wasn't that difficult. I used two soldering irons, one screwdriver and a college-age son to do the job. After sucking all the solder off the joints I gently pressed on the two pins at each corner with the two irons while my son pried on the other side with the screwdriver. It took about six times around to ease the pins out, but now it's done and the board looks good!


----------



## royewest

I suppose that's why they let them home over the holidays...


----------



## tangent

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Finally got around to casing up my YJPS_

 

It's a beautiful build, Nate!

 Which 1455 is it?

  Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_The transformer is off, and it wasn't that difficult. I used two soldering irons, one screwdriver and a college-age son to do the job._

 

That counts as difficult. You owe yourself and your son a beer. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_I am clinging (irrationally?) to the hope that the opamp may be OK after all._

 

Quite irrational, I'm afraid. It's possible it "works" in some limited sense, but complete lack of damage is more than I would hope for. You might as well replace the op-amp with a 741 if you're not going to worry about running a high-end supply like this with a damaged error amp.

  Quote:


 do you have any STEPS boards left? 
 

Nope.

 You could pair the transformer with a TREAD, though.

  Quote:


 I used 70053 in the one I built earlier and it works nicely. 
 

The YJPS is less forgiving of excess voltage appearing on its output, since there's a plain old op-amp there. Also, it splits its heat load between two smaller heat sinks instead of using one really big one like the STEPS did. There is room on the YJPS for a bigger heat sink on Q2, but then that pushes parts of the regulator closer to the transformer, probably not a good idea.


----------



## tangent

Schubert, I was thinking more about this, and it might be a good idea to choose a different op-amp, one made for greater than +/-15V supplies. There aren't a great many to choose from, particularly if you restrict your choices to JFET-input chips, which are reportedly more stable in the Jung regulator. (It's not a DC offset issue, it's an RFI susceptibility one.)

 I might try an OPA604 myself, as it's actually rated for +/-24V. There are a fair number of +/-18V supply chips out there, too.


----------



## n_maher

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_It's a beautiful build, Nate!

 Which 1455 is it?_

 

It's the T2201 and was built to match a friend's M³. Using short standoffs (3/8") there was about 1/16" clearance between the heat sinks and the top of the case.


----------



## ruZZ.il

Schubert: I once removed a trafo, pretty much the way Tang described, also cause I used one with too high of an output voltage.. went pretty smoothly though. 

 Nate, Got any comparisons to a STEPS with the M^3? I need to get myself some sort of drill press too.. I strive to have holes that aligned


----------



## schubert

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_That counts as difficult. You owe yourself and your son a beer. 
	

	
	
		
		

		
			



_

 

Case work is difficult (for me, anyway) - this was merely tedious. No beer - he's just working off his tuition! 
	

	
	
		
		

		
		
	


	




 ruZZ.il: What kind of problems did the transformer cause?

 Tangent: The sturdier opamp sounds like an excellent idea. Maybe I'll order an OPA604 - if I look for others, are there any other parameters to keep in mind, besides JFET and high voltage?


----------



## n_maher

Quote:


  Originally Posted by *ruZZ.il* /img/forum/go_quote.gif 
_Nate, Got any comparisons to a STEPS with the M^3? I need to get myself some sort of drill press too.. I strive to have holes that aligned 
	

	
	
		
		

		
		
	


	


_

 

Not from me, the PS is for a friend. I don't own anything that uses a power supply below 250V anymore. And all the fab for that case was done with a hand held drill, it's too cold in the garage to justify using the press for little stuff like this. 
	

	
	
		
		

		
		
	


	




 Measure twice, use a punch and drill carefully.


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_if I look for others, are there any other parameters to keep in mind, besides JFET and high voltage?_

 

Low noise is probably the most important thing. I wouldn't go much higher than what the AD825 puts out, 12 nV/rt.Hz. The 604 is a little lower, at 10 nV/rt.Hz. You can get down to about 4nV or so if you look hard enough, though you might give up too much else.

 Don't go experimenting if you don't have an oscilloscope. You need to test this carefully before accepting it. You're pioneering here.


----------



## ruZZ.il

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_ruZZ.il: What kind of problems did the transformer cause?_

 

Well, I was using +/-15v AC and dropping it to about 26Vdc which is around a 10v drop for the regulator, which was causing quite some heat on it so I wasnt even fully biasing my M^3. Changing to a +/-12v cut the voltage drop by around 70%.. fully biased and still much less heat.


 Nate: Ah. I guess I need a punch


----------



## n_maher

Quote:


  Originally Posted by *ruZZ.il* /img/forum/go_quote.gif 
_Nate: Ah. I guess I need a punch _

 

This is pretty similar to the one that I use to mark holes before drilling. And a few thousand holes of practice doesn't hurt either.


----------



## schubert

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Don't go experimenting if you don't have an oscilloscope. You need to test this carefully before accepting it. You're pioneering here._

 

I have access to an oscilloscope, though I've never used one before. I could get one of the physics teachers here to show me how to use it, I suppose, but I'm not sure what I would be looking for in a power supply - it's not like I could send a square wave through it. Maybe I'll leave the experiments to you. If you try an OPA604 and it works, will you post the results?

 I must have done something else wrong if ruZZ.il used the same transformer and the only problem he had was heat/inefficiency. Either that or I got a bad part somewhere. When the new transformer comes I'll start by removing the opamp and one end of R8 and see what happens. In the meantime I'm without my PPA...


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_I'm not sure what I would be looking for in a power supply_

 

In this case, oscillation. It'll be dead obvious. You just hook the scope probe across the output (ground clip to TP3, probe tip to TP6), set it for AC coupling, and set the bandwidth and vertical settings so you can see the scope noise, typically a few mV. That's all you should see; just a nice fuzzy line a few mV high. If it's oscillating, you'll probably see a huge periodic waveform; at the very least, enough high-speed "ripple" that it pokes up over the scope noise.

 Do the test with the supply just sitting there idle, then put a dummy load across it, re-test, then put a real load on it and re-test.


----------



## schubert

So I'm not in danger of frying the oscilloscope by feeding all 30V or so directly into it?! I suppose then that "AC coupling" puts a capacitor in the path or some such thing to block DC? If I'm not liable to commit "oscilloscopicide" maybe I'll try it.

 Would a power resistor work as a dummy load?


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_So I'm not in danger of frying the oscilloscope by feeding all 30V or so directly into it?!_

 

Depends on the scope and the probe you use with it. A decent scope will have the input voltage limit printed on the front of the scope near the probe connection. The most common probe type is a 1/10x passive probe, which on the 10x setting cuts the signal down by 10x. So, if the scope says 30V but you use a 10x probe, you're still fine. Switch the probe to 1x, and you're right on the edge of damaging the scope.

  Quote:


 I suppose then that "AC coupling" puts a capacitor in the path or some such thing to block DC? 
 

Yes.

  Quote:


 Would a power resistor work as a dummy load? 
 

Yes.


----------



## schubert

I looked at the scope again, and it has a limit of 600V, so there's no problem there. I was puzzled by one thing - appended to the voltage limitation was "(P.P + DC)". Any idea what the "P.P" is? The manual to this thing has long since disappeared (as has the probe!)


----------



## tangent

AC peak-to-peak, plus DC offset.


----------



## schubert

OK, I replaced the transformer and retested, with virtually the same result (except of course about 10V less) - still around 1.6 volts down over the LM317. I removed the opamp and lifted R8 - same result, 1.6V (also same result everywhere else). I suppose that pins it down to the LM317 - I'll replace that and post again with the results.


----------



## Phil Townsend

I have mated the YJPS with the USB/DAC. It works.
 The DAC is drawing about 290ma at 12vdc. No noise, no voltage sag, Maybe the heat sink are a tad too warm. I had to size them to fit inside the case so they are a bit shy of the correct size.
 The PS has really helped the sound on the DAC. I am quite happy...
 Thank you Warren

 Phil
 Santa Fe, NM

 Sir, May I have another?


----------



## tangent

Quote:


  Originally Posted by *Phil Townsend* /img/forum/go_quote.gif 
_I have mated the YJPS with the USB/DAC. It works._

 

Good to hear it.

  Quote:


 Sir, May I have another? 
 

There are some more things I want to do before I make the next run. Changes so far:

 - Enlarged the mounting holes in the corners of the board

 - Added separate test points for CGND and RGND, so you can test the three main sections of the circuit separately. (Changes most of the TP numbers, unfortunately.)

 - Lots of tiny little part positioning tweaks and such

 Still left to do:

 - While assembling my first YJPS v1.1, it seemed to me that the VOUT and jumper pad scheme is probably a touch on the complex side. I want to look back at it and see if I can simplify it, or at least make it more elegant.

 - Add another hole to each of the big film caps, C1-C3, allowing use of 12.5mm pitch caps.

 - I'm considering moving at least D2 and Q1 to the other side of Q2 so you have the option of laying the transistor down flat for low-profile cases. I'd probably move R5 and R6, too if I did this. You can already do this with U1.

 - The heat sink mounting holes are too small. They're going to be enlarged to allow at least #4 screws.

 - I'm thinking of adding a zener/SCR type crowbar across the output of the supply to force the fuse to blow if you go over a safe output voltage for the op-amp, to prevent a recurrence of the problem Schubert's having.

 Anything else for the wishlist?


----------



## schubert

Replaced LM317 - no change. Still -1.5V over LM317 with no op amp or R8 in circuit. -1.1V over TP5-TP6. D2 does not light. Any ideas?


----------



## tangent

Now I'd start poking around the CCS area. It's beginning to look like it might be misbehaving for its own reasons, not just indicating problems in the surrounding bits. 

 Q1 might not be a transistor any more, for instance; it's rated for 50 V, but a small inductive spike on top of that when turning it off for the first time could have pushed it over the edge. Use a diode tester to see if the EB and CB junctions still look like diodes. If there's any doubt, remove Q1, then power it up again to see if D2 lights. If it does, Q1 was probably fried, and explains everything...no CCS, no regulator.

 My second best guess is that your use of nonstandard components has something to do with it. You didn't get "creative" with the R3 or R4 values, did you? You've checked for shorts or opens with all those free-range components?


----------



## schubert

I don't have a diode tester - I assume you mean something that will test whether current will go only one way through a diode. Could I rig one using a 9V battery, LED and a resistor?

 Anyway, I just went ahead and removed Q1 and powered up. Sure enough, D2 lit up, albeit dimly. Large voltage drop over the LM317 resulted. I replaced the Q1 with a new transistor, but it didn't do any good - I'm back where I started.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_My second best guess is that your use of nonstandard components has something to do with it. You didn't get "creative" with the R3 or R4 values, did you? You've checked for shorts or opens with all those free-range components?_

 

I definitely try to avoid being creative, especially with a circuit like this. I had already thought of the possibility that I somehow got the wrong resistors in R3 and R4. I pulled R3 and checked, and both R3 and R4 are spot on. I've also checked all the rest of the resistors, and they're OK too. I've been over the rest of the circuit too, and there doesn't seem to be any connectivity problems.

 The only parts besides the hodgepodge of resistors (which are all 1% metal film) that are not right off the parts list are C9 and D2. I ordered the quantities specified on the list w/o checking the schematic (having missed a forum warning about discrepancies) and ended up with 4 C5's and not enough 100uF for C8-C11 (somehow I missed C11 when ordering). So, C9 is an axial electrolytic 100uF cap from Radio Shack. Somehow I doubt that's the problem, though.

 So that leaves D2. Could the wrong LED be causing the problem? To be truthful I don't remember what I did when I ordered, but I do remember putting an ordinary diode in that spot. (The recommended part is currently non-stocked at Digikey and has a 5000 piece minimum - and it's listed as "obsolete" at Mouser, though a "638" replacement version is available). Upon rechecking (and before I ever powered up) I realized I needed an LED there, so I removed the diode and put in a green LED from RS. Before putting it in I hooked it up with a 9V battery and a resistor and measured the voltage drop. It was very close to 2V, so I thought it would be OK. (Yes, I suppose this does qualify as "getting creative" 
	

	
	
		
		

		
			





) Have I made a raw newbie mistake? In a way I sure hope so, because the relief of getting this thing working would far outweigh the embarrassment!


----------



## schubert

I replaced the D2 LED (and C9) with the recommended parts, and (no surprise, I suppose) there was no change - still ~1.56 volts over the LM317. The LM317 is healthy - I took it out and tested in the following circuit:
Attachment 13127
 The voltage drop over the resistor was 1.24V, about what was expected.
 I also tested all the transistors for conductivity using a 9V battery, 1K resistor and an LED. All tested identical to unused transistors right out of the package - that is, the PNP versions conducted as long as the negative was connected to the base, and the D44 was opposite. I lifted R6 before testing Q1, and removed the D44 to test it.
 Here are the voltages:
 R3: .617V (+adj to out-) (.617mA)
 R4: .513V (+adj to D44-) (.622mA)
 I think these may be normal - they add up to the current expected with a 1K resistor in the adj-out loop of the LM317.
 D2: 1.241V 
 R5: 38.2V (1.91mA)
 R6: .513V (+TP5 to Q1-) (2.06 mA)
 Q1: 7mV (+E to C-)
 Q1: 726mV (+E to B-)
 Q1: 723mV (+C to B-) (yeah, they don't add up - the numbers fluctuate a little)
 D44: 1121mV (+C to E-; 539mV over CB, 603mV over BE)
 output: 38.5V (+TP6 to gnd-)
 R8 is still disconnected.





 I'm tearing my hair out over this one. Anybody have any bright ideas about what to try next?


----------



## tangent

At what points have you replaced the op-amp? Right now, it may be dead due to the high output voltage, but if you replace it and the rest of the regulator is fine, as seems to be the case, it shouldn't die because it's going to maintain proper regulation.


----------



## schubert

These voltages are all with the op amp removed. I was concerned because I wasn't getting the ~2.3V drop across the LM317 I was expecting (though I do get ~2.1V from the input pin to the adj pin). I have a new op amp - should I go ahead and put it in? I haven't done so yet because I didn't want to fry another one. Besides, I still have 38.5V across the op amp rails.
 Without the op amp, is the 1.1V drop over the D44H11 OK? I thought it should be more.
 Also, D2 is still not lit - I assume it should be.


----------



## tangent

I'd investigate that D2 failure first.

 Also, when you do decide to put the op-amp back on, I'd at least temporarily wire the transformer secondaries in parallel to drop the output voltage to something that can't harm the op-amp if the regulator continues to not be a regulator. Only revert to your current series configuration once you've got the circuit behaving sanely.


----------



## schubert

Well, I rewired the transformer for parallel and tried again - same result. Now I'm getting around 20.4V unregulated, the same 1.5V drop over the LM317, and 0.8V over the pass transistor rather than 1.1V. D2 still does not light, though it's physically fine.

 Then I put a new AD825 in, and it made no difference except that D2 lights for about a second and then shuts off (as it did at first with the 70053 transformer). There's now only 20V or so across its rails, so I'm pretty sure I haven't fried it. I also replaced Q1 (again) and the D44H11 to no effect.

 A question about the LM317 - should there not always be a 1.25V drop across R3 (LM317 adj and out pins)? Isn't that what an LM317 is supposed to do? I'm only getting around 0.6V, but if I take the same LM317 out of this circuit and put it in a simpler one, I get the 1.25V drop just fine.

 I'm trying to gain some understanding of this circuit. As far as I can see the output voltage is determined by controlling the current at the base of Q2. With no op amp present, D2 doesn't light because the current that would usually light it is going through Q1. There's no reason for it not to, since the base is at a lower voltage than the emitter. I'm guessing there's also some EC current, since there's minimal voltage drop over Q2.

 When the op amp is added, now there's current from D3, which heads to the Q2 base pin and controls Q2's conductivity. This also opposes current from Q1, only temporarily in my case, since current is forced through D2 for about a second. Ideally this should be steady-state (more or less) and D2 should remain lit, but in my case the current from D3 is being stopped and current from Q1 is leaving Q2 open, and I get a very small voltage drop, which is unaffected by VSET.

 I need to figure out why current is getting through Q1 when it should be going through D2 (at least when the op amp is installed). The Q1 I just took out had an hFE of around 350 (the data sheet said 250 min) and the one I put in was around 650, so I think they're both OK.

 Does this analysis sound OK, or am I totally off track? As you can tell I'm obviously no electrical engineer, but I'm trying to learn as much as I can. Thanks to tangent for putting up with my ignorance, and to anyone else who might be able to help.


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_Then I put a new AD825 in, and it made no difference except that D2 lights for about a second and then shuts off_

 

I know of nothing in this circuit that could do this other than the protection circuitry in the op-amp itself. Everything else should act more or less instantly. Protection circuits, though, cut in after a short time and stay clamped, until either power or the badness goes away, depending on how they're designed.

  Quote:


 There's now only 20V or so across its rails, so I'm pretty sure I haven't fried it. 
 

Yes, if nothing else, this exercise has removed one source of FUD.

  Quote:


 A question about the LM317 - should there not always be a 1.25V drop across R3 (LM317 adj and out pins)? Isn't that what an LM317 is supposed to do? I'm only getting around 0.6V, but if I take the same LM317 out of this circuit and put it in a simpler one, I get the 1.25V drop just fine. 
 

Yes, you understand it correctly, but I can't offer any enlightenment about its behavior.

  Quote:


 With no op amp present, D2 doesn't light because the current that would usually light it is going through Q1. 
 

No. If Q1 is still a PNP transistor, there's something on the order of 1 uA coming _out_ of its base, and going down to ground through D2's ballast resistor. (The exact value is Ic / hFE.) Current flows exactly opposite to the way you propose.

  Quote:


 the base is at a lower voltage than the emitter 
 

I think you're assigning FET-like behaviors to a bipolar here. Bipolars are current-controlled, not voltage-controlled. It doesn't matter whether the emitter is above the base or below it. What matters is the current going into or out of the base, and what's going on around the transistor. I wrote up how this CCS works in the op-amp linear regulators article.

 Remind me: with Q1 out, D2 lights? What about when only Q2 is out of the circuit?

 Is D3 still a zener?

 Does removing Q3 and Q4 help?

 Have you checked for PCB trace breaks or manufacturing errors?


----------



## schubert

I read the linear regulator article, though complete understanding is yet a little way off.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Remind me: with Q1 out, D2 lights? What about when only Q2 is out of the circuit?_

 

Yes, D2 lights dimly - not nearly as brightly as it does (temporarily) with the op amp in. I thought about powering up without Q2, but I wasn't sure it was safe or advisable. I'll try it.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Is D3 still a zener?_

 

No clue. I know what a zener is and what it does, but not how to test it. I'll read the data sheet and try to figure out a way to see if it's still functioning. To tell the truth I didn't realize D3 was a zener - is it reversed biased when the unit is functioning normally? 

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Does removing Q3 and Q4 help?_

 

Haven't tried that either, mostly because the basic problem is there when Q3 and Q4 are out of the circuit (that is, with no op amp and R8 lifted).

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Have you checked for PCB trace breaks or manufacturing errors?_

 

I've checked part of the board, but I haven't gone through it systematically since I've been focussing on the parts. I'll do it. It's the only thing left that makes sense, since the parts seem to be OK.

 I'm also going to lift one end of R4 and see if I get 1.25V over R3.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_If Q1 is still a PNP transistor, there's something on the order of 1 uA coming out of its base, and going down to ground through D2's ballast resistor._

 

That's what I meant to say - current is draining out of the base of Q1 and to ground through R5. With no op amp, this current has to come from R6, doesn't it? I didn't think it could come from the base of Q2. If it's coming through R6, then it's bypassing D2, which then doesn't light.


----------



## tangent

Quote:


  Originally Posted by *schubert* /img/forum/go_quote.gif 
_Yes, D2 lights dimly - not nearly as brightly as it does (temporarily) with the op amp in._

 

Something to investigate, then. There's apparently some sneak path changing the current through the LED. Normally there should be only one thing controlling that, R5, which is constant. If somehow the other path were through the op-amp output, it could be a surge of current that makes the LED very bright until the op-amp output shuts down due to overcurrent.

 I've stared at the schematic and no obvious path for this pops out at me. Every theory I come up with makes no sense, if you assume no shorts on the PCB and the components are all functioning.

  Quote:


 I know what a zener is and what it does, but not how to test it. 
 

Just check the voltage drop across it.

 In fact, why not check the V drops everywhere? Print out a copy of the schematic, write down all the voltages you see relative to TP3 on every straight line on the schematic. For instance, between Q1 and Q2, you have several choices of where you can take the measurement: Q2 base, Q1 collector, D3 cathode, and + side of C8. Check at the easiest one to get to in each case, so you reduce the chance of slipping with a probe and blowing something else up, invalidating the test. In this particular case, it's probably the D3 cathode.

 Then, go through and calculate all the voltage drops across each pair of nodes.

 I'd confine myself to just the second page of the schematic. Everything from TP4 back seems to be behaving sensibly.

 If you study the result and nothing pops out at you as a cause, scan it in and post it here.

  Quote:


 D3...is it reversed biased when the unit is functioning normally? 
 

Yes. 6.8 V.

  Quote:


 current is draining out of the base of Q1 and to ground through R5. 
 

Yes, but again, it should only be a tiny amount, in the single-digit microamp range, not enough to affect anything materially.

  Quote:


 With no op amp, this current has to come from R6, doesn't it? I didn't think it could come from the base of Q2. If it's coming through R6, then it's bypassing D2, which then doesn't light. 
 

Current goes down _both_ paths. It's not either/or. There is no switch between R6 and D2, causing current to take one path or the other. The current through R5 is almost entirely that through D2, plus a tiny bit of leakage through Q2's base. What current passing through R6 doesn't leak through Q2's base goes out Q2's collector.


----------



## rds

When can we expect to see more boards available?


----------



## tangent

I'm holding off on finalizing the v1.2 design until I get comments from one other prototype builder, at least. I'd also like to get schubert's issue resolved before going to production, too, in case there's a wider problem to be dealt with, rather than just some one-off issue. On top of all this, I have other projects I have to get to first.

 All of this together means final boards are no less than a month away, probably farther.


----------



## grenert

One more report of a successful YJPS v1.1 build. Mine is a rock-steady 12V. I used a 15+15V transformer with parallel secondaries. Part selection for the resistors was:
 R10=499R
 R11=348R

 Unloaded, I had 22mV RMS ripple after the filter caps. I have no way to measure ripple in the later stages.

 Thanks to Tangent for another great design!


----------



## schubert

Congratulations grenert. I hope to be able to post the same message soon, though my success will be through a very circuitous route!


----------



## schubert

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Current goes down both paths. It's not either/or. There is no switch between R6 and D2, causing current to take one path or the other. The current through R5 is almost entirely that through D2, plus a tiny bit of leakage through Q2's base. What current passing through R6 doesn't leak through Q2's base goes out Q2's collector._

 

I realize that it will head both directions - I was mistaken about how much current Q1 would let pass through its base. Without the op amp I had 1.91mA through R5 and 2.06mA through R6, so I figured Q1 was a wide open gate (Which I guess it can be, E to C) and D2 wasn't getting enough current to light (only 1.24 volts across it). Since removing Q1 and thus restoring that microamp current was enough to light it dimly, that lends support to the idea of a rogue path to ground, probably through R5 - otherwise where is R5's current coming from?

 With the op amp there is only 0.9mA through R5 and almost exactly 1mA through R6 - still indicative of a leak somewhere.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Just check the voltage drop across it._

 

I already had checked the voltage across D3 (18V), but I'm not sure it will reveal much since the op amp has pretty much shut down and there's no current through D3 (no voltage drop over R7). I checked the resistance of D3 and it behaved the same as an identical uninstalled part - around 470 ohms in one direction and unmeasureable in the other.

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_In fact, why not check the V drops everywhere? Print out a copy of the schematic, write down all the voltages you see relative to TP3 on every straight line on the schematic._

 

I did this with the op amp removed and posted it earlier (as a list), and I've redone some with the op amp back in. The only thing that stands out that may be significant is that the 2.3V drop I should be seeing TP4-TP5 is being scrupulously maintained over TP4-TP6 instead. I noticed the same thing with the other transformer setups as well, except with the higher voltages it was around 2.6V instead of 2.3V. It didn't click with me until I put the opamp back in and noticed that even though the voltages over R3 and R4 changed by around -30% or so, TP4-TP6 remained rock steady at 2.3 V (1.5V TP4-TP5 and 0.8V TP5-TP6 in each case). LM317 must be confused somehow about the resistance between its out and adj pins - but not nearly as confused as I am! 
	

	
	
		
		

		
		
	


	




 Any ideas? 

 I'd like to find that 1.25V drop the LM317 is supposed to maintain - it must just be in a different place than I think it should be (that is, across R3). I thought maybe it could be that 1.24V drop across D2...but with the op amp it's 0.977V.

 There doesn't seem to be any trace breaks that I can find. I'll start looking for sneak paths - this will be a lot of trial and error.


----------



## tangent

Have you been cleaning the board?


----------



## schubert

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Have you been cleaning the board?_

 

Well, no, I hadn't been, though it was on my list of things to try. So I gave it a thorough scrubbing, but there was no change.

 I measured all the voltages I could think to measure and put them on the schematic. I included voltages I had measured with no op amp installed. I also included a few I had made with the op amp installed but not powered - I temporarily replaced Q2 with a new part (no change) and when I reinstalled the old one I didn't get the pin soldered to the top trace that led to op amp pin 7, so the op amp had no power for a while (it was soldered to the bottom trace, though). I've looked over this quite a bit, but without knowing the voltages for a healthy unit it's hard for me to try to pinpoint the problem.
Attachment 13782
 If nothing sticks out as being obviously of culprit nature I'll start pulling parts one at a time. One thing I noticed, which may or may not mean anything - when first plugged in D2 stays lit for about as long as it would take to charge a capacitor. Could a capacitor be causing problems? Perhaps I'll replace C8-11 one at a time.

 I realize all these numbers don't exactly add up right - my meter is no great shakes.


----------



## sachu

I could really use a board for a power supply build for my Scott Nixon USB DAC. I want to move away from using the SLA batteries and put in a nice solid power supply. This seems perfect.

 An idea on the parts cost for this project?

 Can you get a 5 V output from this design?


----------



## Beefy

I don't think that this is available yet. Have you considered a σ11?


----------



## sachu

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_I don't think that this is available yet. Have you considered a σ11?_

 

I have..i just don't think the sigma11 is good enough for a digital supply.


----------



## Beefy

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I have..i just don't think the sigma11 is good enough for a digital supply._

 

Why not? Tangent reports 7µV noise. AMB reports less than 12µV. Both are far superior to commercial designs.


----------



## sachu

Quote:


  Originally Posted by *Beefy* /img/forum/go_quote.gif 
_Why not? Tangent reports 7µV noise. AMB reports less than 12µV. Both are far superior to commercial designs._

 

I was thinking more on the lines of using a programmable shunt regulator on the likes of TL431, a transistor, a few resistors and coupling caps to get a good enough PSRR . I need a rock steady PSU at 5V with very low noise as this is the supply to the receiver and the interpolation filter on my DAC...


 I understand that the error amplifier in the sigma11 is basically what is governing the PSRR.The other supply I am considering is COlin's regulator that is being discussed here.

 I don't need a super high current regulator design, 300mA would be plenty enough. I would even settle for half that.

 The parts cost on the sigma11 is not too bad, abt 20$ considering that it would go into my existing DAC case...


----------



## tangent

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_An idea on the parts cost for this project?_

 

Fully loaded, with case and all, something like $90. I haven't really priced it out...that's just based on the old STEPS cost of $70 for something similar, plus the additional costs here. Might even be closer to $80.

  Quote:


 Can you get a 5 V output from this design? 
 

Sure. You need to change the voltage reference, probably the op-amp, and maybe the gain setting resistors. You need an op-amp that will itself run well on 5 V, and for the rest I recommend a 2.5 V reference and a gain of 2. This is covered in the YJPS docs, but I haven't tried it, so you'd be pioneering. Jung covered this in the original 1995 series of articles, and recommended the AD848 for the op-amp.


----------



## sachu

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Fully loaded, with case and all, something like $90. I haven't really priced it out...that's just based on the old STEPS cost of $70 for something similar, plus the additional costs here. Might even be closer to $80._

 

thanks for the reply tangent. 

 The parts cost is inclusive of the transformer I presume? I already have a transformer with a separate secondary winding of 0-6V..after rectification I should get around 7V DC. Would that be enough to use as input to the design?

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Sure. You need to change the voltage reference, probably the op-amp, and maybe the gain setting resistors. You need an op-amp that will itself run well on 5 V, and for the rest I recommend a 2.5 V reference and a gain of 2. This is covered in the YJPS docs, but I haven't tried it, so you'd be pioneering. Jung covered this in the original 1995 series of articles, and recommended the AD848 for the op-amp._

 

Do you have any more boards left ? Does p-2 p wiring have any effects on your design?


----------



## tangent

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The parts cost is inclusive of the transformer I presume?_

 

Fully loaded, yes. Nothing left out.

  Quote:


 I should get around 7V DC. Would that be enough to use as input to the design? 
 

No. The Jung 2000 design is a "high drop-out" regulator. To get 5 V out, you might need as much as 10 V unregulated. This makes it less than 50% efficient at such low voltages, I know. If you want efficiency, there are many other designs to choose from.

  Quote:


 Do you have any more boards left ? 
 

No. I'm still tweaking the design. What with that work ongoing and manufacturing time, we're a month or two away from seeing final boards.

  Quote:


 Does p-2 p wiring have any effects on your design? 
 

Are you asking what would happen if you made it on a perfboard? It's a fairly "fast" design, so it benefits from a good, tight PCB layout. If you switched to a slow op-amp, it could tolerate a big sloppy layout, but then you'd lose a lot of the performance advantages.


----------



## sachu

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Fully loaded, yes. Nothing left out.

 No. The Jung 2000 design is a "high drop-out" regulator. To get 5 V out, you might need as much as 10 V unregulated. This makes it less than 50% efficient at such low voltages, I know. If you want efficiency, there are many other designs to choose from.
_

 

Yeah, I was hoping to use the separate winding on the transformer for further isolation between the analog and digital supplies. is there any detriment in using the same secondary taps for both digital and analog sections of the DAC?

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_No. I'm still tweaking the design. What with that work ongoing and manufacturing time, we're a month or two away from seeing final boards._

 

Dang..this is the limitation that I am facing with the Toole regulator boards on diyaudio.com too. 

  Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Are you asking what would happen if you made it on a perfboard? It's a fairly "fast" design, so it benefits from a good, tight PCB layout. If you switched to a slow op-amp, it could tolerate a big sloppy layout, but then you'd lose a lot of the performance advantages._

 

yes..that is exactly what I asked. It is interesting that a few years back I had read one of the many Analog Devices application notes which said that most prototyping they did for fast designs were point to point. 
 With the minimal use of wires I wonder if point to point would be fast enough.


----------



## tangent

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_is there any detriment in using the same secondary taps for both digital and analog sections of the DAC?_

 

Oh, probably, but I'm not the right guy to ask. I've done nearly zero digital audio DIY.

  Quote:


 I had read one of the many Analog Devices application notes which said that most prototyping they did for fast designs were point to point. 
 With the minimal use of wires I wonder if point to point would be fast enough. 
 

The issue is parasitics. The document you're talking about probably referred to ratsnest type builds, where you take a copper-clad board, tie that to some solid ground, then build your circuit in the air above it, with connections to ground as needed, and everything else held up above the board only by the stiffness of the wires. You still have to keep details in mind like minimizing the distance of bypass caps from the nodes in the circuit that need to be bypassed. Other than that, this keeps parasitics very very low: thick wires for low L's and R's, and air dielectric makes for low C's.

 This sort of build doesn't hold up well to vibration. It's good for prototyping and hackery.


----------



## sachu

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_Oh, probably, but I'm not the right guy to ask. I've done nearly zero digital audio DIY.

 The issue is parasitics. The document you're talking about probably referred to ratsnest type builds, where you take a copper-clad board, tie that to some solid ground, then build your circuit in the air above it, with connections to ground as needed, and everything else held up above the board only by the stiffness of the wires. You still have to keep details in mind like minimizing the distance of bypass caps from the nodes in the circuit that need to be bypassed. Other than that, this keeps parasitics very very low: thick wires for low L's and R's, and air dielectric makes for low C's.

 This sort of build doesn't hold up well to vibration. It's good for prototyping and hackery._

 


 That is exactly what I am referring to 
	

	
	
		
		

		
			





 The use of a copper board to build the circuit. 

 I built a diode ring mixer with trifilars a couple of quarters back using a copper board and the rest of the stuff suspended in the air....wa quite fun and worked lke a charm..agree with you about the vibrations and such.


----------



## tangent

Perfboard fixes the structural problems, but adds a lot of parasitics. This is what I was warning against above. It's not a guarantee of failure, just a risk.


----------



## PJPro

Did schubert ever sort out his problem?


----------



## rds

I'm really digging the production YJPS







 I'm really skeptical of my ability to hear any difference between the YJPS and STEPs powering my PPA v2, but it's so cool and at about $100 total I can't resist 
	

	
	
		
		

		
		
	


	




 This thing can put out a ton of power too, with ability to fit a +-12V 25VA transformer.


----------



## linuxworks

2009 is the year of the red pc board??






 lets see some pics when you populate it.


----------



## tangent

Thanks, rds!

 FYI, I just got these in a few days ago, and put them in the shop without having built one yet so the impatient can get one before then.

 Changes since the v1.1 prototypes:

 - added an SCR-based crowbar on the output to prevent the "schubert" problem

 - C5 previously allowed three caps from 10mm to 18mm, but now allows four 10-12.5mm caps, three 16-18mm caps, or two 20-25mm caps

 - C1, C2L and C2N now allow 12.5mm pitch caps in addition to the 10 and 15mm pitches perviously allowed

 - changed VOUT to use the 4mm pin spacing Molex KKs instead of the 0.1" variety, so you can use 18 gauge wire for the regulated output to the load

 - Moved A-D and W-Z transformer jumper pads closer to the transformer pins; so, longer jumpers required, but jumpers can use more copper than I could lay down on the PCB between these points.

 - JRSG and JRSV are now Molex KK connectors (0.1") instead of wire jumpers, so you can more easily set up remote sense connections.

 - larger mounting holes for board and heat sinks

 - 2 more test points

 - lots of minor trace and part positioning tweaks


----------



## Voodoochile

Nice looking board! I like the lightning bolts. 
	

	
	
		
		

		
		
	


	




 Are those fat holes for snap-ins?


----------



## tangent

You know, I don't remember exactly why I enlarged the main board mounting holes. Maybe just to allow #6 bolts?


----------



## schubert

Quote:


  Originally Posted by *PJPro* /img/forum/go_quote.gif 
_Did schubert ever sort out his problem?_

 

No, I didn't - I put it away, figuring I'd get one of the new boards and try again, and things got busy around here, so I've been away from the forum for a while. I noticed on a recent post by tangent that one of the changes in the new board was related to my problem ("added an SCR-based crowbar on the output to prevent the "schubert" problem"), but I didn't understand it. Can anyone enlighten me? Tangent, did you figure out what the problem must be?

 (I've since read tangent's description of the "crowbar", so now I have a general idea how it works. As far as I can tell it doesn't fix my problem, but just prevents it from doing significant damage.)


----------



## tangent

It was my understanding that all of the problems you had after the overvoltage event were just secondary effects of that same problem. It's possible your power supply really has some independent problem, but lacking further details from you...

 Besides which, the crowbar is still a good idea.


----------



## Voodoochile

Make sure your crowbar does not say "Stanley" on it. That would definitely cause trouble.

 I reserve the Stanley crowbar for repairs with extreme prejudice only.


----------



## digger945

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm really digging the production YJPS_

 

Yea I'm diggin' it too.
 Having read the tangent website and this thread, I can't seem to find the safe current limit, or power limit, of this PS. Would it go 160mA or more at 6.6v?

 Thank you so much Tangent for making this pcb available, there is not much to choose from elsewhere.


----------



## tangent

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_I can't seem to find the safe current limit, or power limit, of this PS._

 

R6

  Quote:


 Would it go 160mA or more at 6.6v? 
 

Yes, if you change the reference, as described here: D4


----------



## dbfreak

Red? Looks like my old 9800 Pro.


----------



## applegd

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm really skeptical of my ability to hear any difference between the YJPS and STEPs powering my PPA v2, but it's so cool and at about $100 total I can't resist 
	

	
	
		
		

		
		
	


	



_

 

Interesting comments, I will build one later then compare it to STEPS and AMB's Sigma22.


----------



## zxc

I plan to build a YJPS for a PPAv2. How important is it to set up a 4-wire remote sensing if the distance between the units will be about a foot (or two feet max)?

 I plan to use a regular 2.5mm DC power connector (18awg). If it will make a difference, I was planning to add a second 2.5mm connector to PPA for remote sensing. Would this work?


----------



## qusp

thats quite a massive distance actually, thats quite a lot of impedance, capacitence and inductance right there. for inductance to have little to no effect, you really should have the supply 10cm or less from the load. in fact i'm of the opinion that its going to pretty much waste any benefit of having a decent regulated supply if you place it that far from the load. you will need to at the minimum bypass the load well to attempt to fight any ripple the distance causes, so absolutely yes, if there was ever a reason to use sensing this is it IMO


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## zxc

I see. It's really difficult to put together a decent arrangement for a PPAv2 powered by a YJPS (each in a Hammond case). If I place the PPA on top of YJPS, the AC-in and DC-out will have to be at the back of YJPS box, resulting in an over 10cm distance between the load and source (and the DC and AC will be close together). If I place the PPA in front of YJPS, then I can have the AC-in and DC-out at opposite ends of the YJPS box. But then there will have to be some distance between the boxes so I can attach the RCA jacks comfortably to the back of PPA. Any solutions?

 By the way, Tangent does not mention the "two separate 2.5mm DC connectors" solution for remote sensing. Can I use this method instead of a, say, 4-pin XLR configuration? I couldn't find a way to get a 4-connector shielded cable (18 awg or larger) at a reasonable price. The connectors are expensive as well.


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## tangent

Quote:


  Originally Posted by *zxc* /img/forum/go_quote.gif 
_How important is it to set up a 4-wire remote sensing if the distance between the units will be about a foot (or two feet max)?_

 

A better question to ask is, why _not_ do it?

  Quote:


 I plan to use a regular 2.5mm DC power connector 
 

Consider this wiring configuration, then.

  Quote:


  Originally Posted by *zxc* /img/forum/go_quote.gif 
_two separate 2.5mm DC connectors...Can I use this method instead of a, say, 4-pin XLR configuration?_

 

Of course.

  Quote:


 I couldn't find a way to get a 4-connector shielded cable (18 awg or larger) at a reasonable price. 
 

I used Canare Star Quad for my recent dual-Hammond 1455 PPA + YJPS build.


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## Volkum

Quote:


  Originally Posted by *applegd* /img/forum/go_quote.gif 
_Interesting comments, I will build one later then compare it to STEPS and AMB's Sigma22._

 

Looking forward to the results. I'm using a STEPS with my PPAv2 at the moment.


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## zxc

Quote:


 I used Canare Star Quad for my recent dual-Hammond 1455 PPA + YJPS build. 
 

Thanks for all your answers. Tangent, how did you place them: YJPS behind PPA, or PPA above YJPS? Did you have the AC-in and DC-out at the same side of the box? How long is your power cable? Did you use a 4-pin XLR connector? Sorry for the long list of questions. I'd like to get his right before ordering all the parts.


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## tangent

Quote:


  Originally Posted by *zxc* /img/forum/go_quote.gif 
_two separate 2.5mm DC connectors_

 

On second thought, don't do that, it sucks.

 If you pull the JRSV connector out by accident -- that being a particular weakness of typical barrel connectors -- you open the regulator's feedback loop, causing the error amp to do who-knows-what. It could pin its output to one of the rails, or start amplifying local RF, or oscillate, or...

 Disconnecting only JRSG is probably less likely to be catastrophic, but can't be good.

 At least with the 2-wire remote sense compromise, unplugging it while everything's powered up doesn't cause problems. If you want full 4-wire remote sensing, use a 4-conductor connector.

  Quote:


  Originally Posted by *zxc* /img/forum/go_quote.gif 
_how did you place them: YJPS behind PPA, or PPA above YJPS?_

 

I have two PPA + YJPS combos.

 The original used a large Par Metals case, so I could place them in an L shape, described in the docs.

 The dual-Hammond one puts the boxes side by side. The output cable runs mostly inside the power supply case, way up in the corner of the case, above the filter cap bank, to get as far away from the transformer as possible. Star Quad is shielded, and I grounded the shield. (Not sure which ground and I don't want to open it up to find out.) I measured the result as very quiet. I'm not sure if it would be as quiet without the shielding, since we're dealing with EMI here, not RFI, but only the shield in Star Quad is ferromagnetic (steel); the conductors are high-purity copper. It could be the shielding is pointless in this particular setup.

 Anyway, the cable exits the box at the upper right corner of the rear panel (viewed from the front) and takes a shortest-possible hop to the PPA, which sits to the power supply's right. There's only 3-4 inches of exposed cable outside the box.

  Quote:


 Did you have the AC-in and DC-out at the same side of the box? 
 

Same end, yes, but the AC comes in the other side of that panel. And again, I'm not sure this matters with pure copper wiring, since copper has such low magnetic permeability.

  Quote:


 Did you use a 4-pin XLR connector? 
 

The 2-box setup uses the barrel connector compromise configuration. The L configuration uses bare hookup wires in twisted pairs.


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## zxc

Thanks Tangent. Any place to get a rather short piece of Star Quad cable?


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## tangent

I got mine at Markertek, which has a $100 order minimum.

 Perhaps you can find high-quality pro microphone cable locally. Canare Star Quad is convenient, but I wouldn't call it special. Anything like it will serve for this purpose.


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## Volkum

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_I got mine at Markertek, which has a $100 order minimum._

 

I just received my $14.98 order (including shipping) from them last week so I'm positive there is no $100 minimum order.


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## TheShaman

Quote:


  Originally Posted by *tangent* /img/forum/go_quote.gif 
_I have two PPA + YJPS combos.

 The original used a large Par Metals case, so I could place them in an L shape, described in the docs.

 The dual-Hammond one puts the boxes side by side._

 

That's very interesting, Tangent.
 Did you have a chance to compare their performance/measurements?

 I'm trying to choose between the two "schools of thought" on the matter (those recommending separate PSUs to minimize EMI/RFI etc and those insisting that short distances are a must) so your input would be more than valuable.


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## zxc

Tangent, in what sequence would you recommend that the PPAv2 & YJPS combo be powered on? 

 Could we have the PPAv2 on all the time and then power on/off only the YJPS? Or the other way around?


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## tangent

Quote:


  Originally Posted by *Volkum* /img/forum/go_quote.gif 
_I'm positive there is $100 minimum order._

 

Good to know they've changed that policy.

  Quote:


  Originally Posted by *TheShaman* /img/forum/go_quote.gif 
_Did you have a chance to compare their performance/measurements?_

 

They're wildly different amps. A head-to-head test wouldn't be any kind of scientific.

  Quote:


 I'm trying to choose between the two "schools of thought" on the matter (those recommending separate PSUs to minimize EMI/RFI etc and those insisting that short distances are a must) so your input would be more than valuable. 
 

This is engineering, not religion: it's all about tradeoffs, not absolute right and wrong. There aren't two schools, just two endpoints on a tradeoff gradient. You probably don't want to be at either extreme.

 Let's first discuss the main problem, EMI, due to the electromagnetic field put out by the power supply transformer.

 I avoid EMI in the L configuration PPA two ways. First, the YJPS uses a toroidal transformer, which keeps the EM flux concentrated more tightly around the transformer than with other types, hence keeps EMI low. Second, the arrangement purposely puts the transformer in one corner of the case, and the audio circuitry in the other. I have two areas inside the case with nothing at all, on purpose. I've seen some similar designs that try to cram more stuff into the case, ending up using space around the transformer...bad idea if it's in any way electrically coupled to the audio circuitry.

 Putting the power supply in a completely separate case and separating those cases with a lot of space is just taking those ideas to an extreme, and it does indeed further reduce EMI. 

 This is at the expense of raising the power supply's output impedance, however, which is a problem if your audio circuit has any kind of dynamically changing current. (And the only time that isn't true is for toy circuits and pure class A.) If the power supply doesn't have any kind of specially low output impedance or awesome regulation, a few tens of milliohms more output impedance probably won't matter. But since we're talking about Jung super regulators here, it does matter; qusp is right. Remote sensing helps, but that's no excuse to put the power supply on the floor and the amp at desk height.

 Note well that I'm only talking about long regulated DC lines here. Long unregulated DC lines are fine if there's local regulation between them and what they're powering. The Creek OBH-11 does this, for example. In terms of my designs, a good setup would be:


> unregulated DC wall wart -> [ TREAD -> PIMETA ]


with the brackets indicating a single enclosure. Here, the impedance of the unregulated DC line isn't really an issue...it's mitigated by the regulator's 80-90 dB ripple regulation.

 That's EMI. RFI is a whole different ball of wax and hair and mud and hash.

 When it comes to power supply issues, virtually all the RFI you care about comes in on the AC line. Keep this in perspective: millions of miles of cable running through a city's worth of RF sources. The YJPS deals with that with the AC line filter. In an EI core based power supply, the transformer is a fair RF filter.

 The other distance -- between the power supply and the powered circuit -- is much smaller, and so of much smaller concern. This wire does form an antenna, which does _ipso facto_ pick up RFI. I have yet to see fixing this problem actually fix an audible problem, however. 

 First, most audio amps aren't terribly sensitive to "true" RF.


> _Aside: Some define RF as beginning just above the audio band, but that's arbitrary. The US Navy communicates with its submarines using sub-audio frequency, because it penetrates both earth and water. That's "radio" to me, but not RF in the sense we're dealing with here._


Second, of those audio circuits that do have a wide enough bandwidth to pick up whatever we'd like to fuzzily define "radio" as today, what does it matter? I guess it could be a contributing factor to some kinds of oscillation, but shielding the DC power cable seems like a bad way to fix oscillation to me.

  Quote:


  Originally Posted by *zxc* /img/forum/go_quote.gif 
_Tangent, in what sequence would you recommend that the PPAv2 & YJPS combo be powered on?_

 

I haven't received any reports of sequencing problems with the YJPS yet, and I haven't had any myself. But then, the cost of the thing means there aren't yet as many YJPSes in the world as there were STEPSen at the same point in its history.

 Of my two PPA + YJPS combos, only one gets turned off regularly. It has two power switches, one on the rear panel at the AC input, which stays on almost all the time, and the other between the amp and power supply on the front, which I toggle off when not using the amp. This amp has been working like that for years. That DC switch gets toggled almost daily.


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## eweitzman

Any plans for a negative regulator board?


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## tangent

Nope.


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