The simplistic Salas low voltage shunt regulator - Page 479 - diyAudio
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Old 5th February 2012, 06:10 PM   #4781
mns80 is offline mns80  Finland
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Quote:
Originally Posted by Salas View Post
Mats, its just down to your aspirations VS investing in time and parts. The law of diminishing returns rears its ugly head at a point. All the difference is at what point you are content. A prudent way is to go step by step and try to stop when differences start to seem like too much complication for nothing to you.
I understand your point. I was also thinking about if I actually win anything on doing supplies for each channel separately. I think I'll make the pcbs and test, if the cooling on the powersupply box is sufficent and the xformers keep cool I'll do 6 shunts and if not I'll use one per voltage. Either way, thanks for your time!

Best regards,
Mats
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Old 6th February 2012, 06:10 PM   #4782
AndrewT is offline AndrewT  Scotland
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One big CCS feeding a resistor for each client circuit.
After the resistor fit the Shunt regulator right on top of the client circuit.
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Old 7th February 2012, 12:11 AM   #4783
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Originally Posted by mns80 View Post
First I tried it out with a CRCRC+317 to get some kind of a feel, sound was good but there was too much noise
Just to be fair to the 317, which I have used very often with very good results:

1) Have you bypassed the adjust leg (100uF to 220uF)?

2) Have you used a not so low-ESR cap at the output, no larger than 220uF?

3) Have you loaded the output with a 100 ohm resistor?

The first one will improve impedance and improve noise (look for Walt Jung comparison measurements on his super-regulator articles).

The second will prevent oscillations for low-ESR caps and/or large caps, and lower noise.

The third seems to improve things all around.

Then I think comparisons can be made, considering parts quantity is quite small on a 3X7 project.
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Old 7th February 2012, 12:34 PM   #4784
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Originally Posted by Salas View Post
Avoid Schottky diodes in the Vref (1A to go 0.6V)...
I am building some 1,2V Disco-versions (post 1616) for DAC:

1) Is there any better version than in post 1616?

2) I wonderd if there was any possible substitute to a resistor/pot (above the CCS Q5). It could be a diode with low Vf like Schottky - but is that a bad idea? If yes - can you get any (low noise) lower Vf than an ordinary silicium diode like 1N4004 of 0,6V ??

3) Christel in his noise-measurements in
Some noise measurements for LEDs and zener diodes

and

http://www.diyaudio.com/forums/attac...amp=1087235682

meantioned a "BC549 BE diode forward biased transistor" (as even more quiet than LED). Does anyone have a schematic how that connection is done?

Peter

Last edited by pedefede; 7th February 2012 at 12:38 PM.
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Old 7th February 2012, 12:37 PM   #4785
AndrewT is offline AndrewT  Scotland
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Connect base to collector.
It is now a two terminal device that behaves like a diode.
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Old 7th February 2012, 03:30 PM   #4786
mns80 is offline mns80  Finland
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Quote:
Originally Posted by carlmart View Post
Just to be fair to the 317, which I have used very often with very good results:

1) Have you bypassed the adjust leg (100uF to 220uF)?

2) Have you used a not so low-ESR cap at the output, no larger than 220uF?

3) Have you loaded the output with a 100 ohm resistor?

The first one will improve impedance and improve noise (look for Walt Jung comparison measurements on his super-regulator articles).

The second will prevent oscillations for low-ESR caps and/or large caps, and lower noise.

The third seems to improve things all around.

Then I think comparisons can be made, considering parts quantity is quite small on a 3X7 project.
Thanks for the suggestions! I had not done 1 and 3 and for the 2nd one I only had some 10uF at home.
Just now I tested with 220uF bypass and 170R load in addition to the 3pcs10uF but I did not notice any improvement. I have to admit that my testing abilities are not more than my hearing as i do not own an oscilloscope. This means I tested and compared the shunt/317 and the suggestions driving phono stage with the preamp at full blast after and there was a big difference.
I do not mean to say anything bad about the 317, it most certanly has its applications, but comparing the noise this way the 1.2R sounds a lot better (less).
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Old 7th February 2012, 03:37 PM   #4787
Salas is offline Salas  Greece
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Quote:
Originally Posted by pedefede View Post
I am building some 1,2V Disco-versions (post 1616) for DAC.......

Peter
1. No
2. Use a normal diode 1N4003 or ''dioded'' BJT.
3. Andrew replied.
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Old 7th February 2012, 03:39 PM   #4788
Salas is offline Salas  Greece
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Mats:

You did not show your MM phono in its thread yet, yes? Take some pics and show there if you may, a few make MM version, maybe they wanna know details.
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Old 7th February 2012, 03:48 PM   #4789
mns80 is offline mns80  Finland
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Originally Posted by Salas View Post
Mats:

You did not show your MM phono in its thread yet, yes? Take some pics and show there if you may, a few make MM version, maybe they wanna know details.
I could try take some pics later this evening of the nice breadboard I have. I started drawing some schematics in eagle last night to prepare for some PCB layout but it will probably be some weeks before I get all the parts, not ordered yet for the shunts, and the PCBs made.
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Old 8th February 2012, 11:02 AM   #4790
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I love this excellent feedback with have good opinion.
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