The simplistic Salas low voltage shunt regulator - Page 60 - diyAudio
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Old 19th June 2009, 09:30 PM   #591
Marinos is offline Marinos  Greece
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This photo is a long due promise to salas.

It's a +-16V Salas shunt powering an OPA627 line stage. It replaced a battery supply with glory. It is powered continuously for one and a half month now without any problem. It keeps astounding me with it's sound that's why I don't bother to rework the wiring and close the box..As salas mentioned at the beginning of this thread I have used 2Ns and still haven't find the time to replace them with 2Sks. Who knows perhaps it will get better sonically...
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Old 19th June 2009, 09:32 PM   #592
Marinos is offline Marinos  Greece
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Oops the photo
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Old 20th June 2009, 12:01 AM   #593
jam is offline jam  United States
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Very neat Marinos, nice job.

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Old 20th June 2009, 12:24 AM   #594
iko is offline iko  Canada
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Quote:
Originally posted by jeepee
Hi Ikoflexer,

Indeed this is an impressive PSSR you achieve.
How much of this 190dB is due to the input current source and how much is due to the sub 0.1mOhm shunt impedance?

If you stick a 1 Ohm resistor between the drain of M2 (the input series PMOS) and the shunt, what is the PSRR at the drain of M2? The intention would be to limit the shunt impedance to 1 Ohm, to test a more 'real life' situation with cables and all.

In practice it would probably be easier to achieve a high current source output impedance then a super low shunt impedance...
I'm not saying it's not possible, but the things I tried didn't work. You can easily play with the circuit using the free ltspice simulator. I can provide you with all the models and whatever needed. Very easy to use. The offer is valid for anyone who would like to do it.

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Anyway with these super numbers you achieve we're deep in the 'learning for fun'/academic debate realm. It's great that you also build these circuits and try them out!
We are, I agree. I don't think it's wrong, as long as we try to also make it real.

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Maybe I should buy a couple of those IRF's and join the fun
Clean and cheap fun, what can I say. If this is the kind of fun that you appreciate, what are you waiting for?
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Old 20th June 2009, 12:30 AM   #595
iko is offline iko  Canada
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Quote:
Originally posted by jameshillj
Iko,
On the above cct, those zeners 4756 (47volt) and 4757 (51volt) will kill the poor ol' k170s pretty quick!

I see you're looking for 200 volt at about 700 mA (140VA?) - have to go towards that "ring of ---" cct for the high volt version, methinks.
Hi James, the voltage drop across them shouldn't be large when the operating points are reached, but maybe for short times this would happen, I'll have to look into it. Thanks!
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Old 20th June 2009, 12:47 AM   #596
iko is offline iko  Canada
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Quote:
Originally posted by AndrewT
M2, the CCS pass element, provides the inrush protection.
It is designed to limit the maximum current into the circuit to it's set value.
Check the dissipation on this device at switch on, i.e. maximum voltage at the input and zero voltage on the +ve rail.
The 9240 should be able to survive an ampere with a 50V input for the very few seconds it takes to charge up all the capacitors that follow the CCS.

Check the dissipation in M1 and M4. They will have different Vds but the same Id.
R1 should allow you to check Id.
Is there a possibility that oscillation is causing the failure rather than over current?
Gate voltage protection Zeners? Where are they? Vgs < Vgs max ALWAYS even during start up, shorting out, shut down, etc.
Andrew, yes, it may have oscillated. The thing is that it happened usually very fast. I'd hear a pop and done. I should try it again soon, and I'll open a new thread, then I'll give you a shout if you can help a bit it'd be great.
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Old 20th June 2009, 02:46 AM   #597
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Sorry Iko,
Just caught up on your adventures with the high voltage regs thread - touchie little fellows at this level, eh!
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Old 20th June 2009, 04:41 AM   #598
Salas is online now Salas  Greece
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Quote:
Originally posted by Marinos
Oops the photo
Very nice! You have also used this white board for your high voltage shunt. What material is it? You just drill as many holes you need? Does not look perforated.
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Old 20th June 2009, 05:07 AM   #599
Marinos is offline Marinos  Greece
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Thanks Jam and Salas.

It's teflon
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Old 20th June 2009, 05:32 AM   #600
Marinos is offline Marinos  Greece
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I use teflon for years now. Very easy to work with. I use those standard brown predrilled boards that you use to make the layout. I mark the holes with a pencil, attach the teflon sheet underneath and drill. The photo shows a guide for 4 shunts board
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