The simplistic Salas low voltage shunt regulator - Page 494 - diyAudio
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Old 31st March 2012, 06:36 PM   #4931
Salas is offline Salas  Greece
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The dummy is a testing load resistor. What of the two values is it? R1 sets the main CCS. If you got 200mA there, then 60mA load is absolutely no problem, should be steady.
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Old 31st March 2012, 07:20 PM   #4932
AndrewT is offline AndrewT  Scotland
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check the voltage across the CCS resistor. If it reduces noticeably when the load current is increased then you have run out of input voltage. It's the CCS that suffers first when you choose the wrong input power.
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Old 1st April 2012, 01:37 AM   #4933
pidesd is offline pidesd  Canada
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Default i just return from a few days of being away from computer.

i see that there is some interest from the little experimentation i did. i must say that i m not entirely satisfied with what i came up with and some builders might not like it. so i ll continue to test parts and when i come up with something(i d like a bit more ''drive'') good i ll post a schematic. to be honest, some mosfets i tried did not have the Gm i thought they would have. i still encourage people to build it and test parts as i cannot test them all.

the build itself is either a sslv1.1 or 1.2 shunt circuit with X paralleled bf862(or other jfet) instead of the ''standard'' CCS. i built it as a negative reg because of the parts i found worthy of trying. so i think that a battery voltage of around 6V should be good. And because it is a neg reg, only one reg must be connected to each battery set.

i will also try a diy resistor with manganin of 200 ohm per meter for a small Vref values

Last edited by pidesd; 1st April 2012 at 01:47 AM.
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Old 1st April 2012, 10:11 AM   #4934
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Quote:
Originally Posted by pidesd View Post
i will also try a diy resistor with manganin of 200 ohm per meter for a small Vref values
Could you elaborate here or open a new thread about how do you do the manganin resistor?
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Old 1st April 2012, 06:49 PM   #4935
pidesd is offline pidesd  Canada
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i would but i feel that as it is right now, this concept is not worthy of getting too much attention. its behavior is a bit unpredictable soundwise, manganin not really available in small quantity as far as i know and this particular gauge is difficult to work with. so i prefer to be sure that people will have fun, in every sense of the word, and post a ''how to'' if i ever come up with something good enough. and in addition, i dont have measurement tools with me.

my interest in doing such a resistor first of all is to evaluate how detrimental were commonly found resistors to the sound in general

Last edited by pidesd; 1st April 2012 at 06:53 PM.
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Old 1st April 2012, 07:04 PM   #4936
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@pidesd
graphite resistor should be your next project?
GRAPHITE RESISTORS
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Old 2nd April 2012, 07:07 PM   #4937
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Hi

Does anybody have some of the circuits in spice? Can't get mine to work ,,,
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Old 8th April 2012, 12:08 PM   #4938
50AE is offline 50AE  Bulgaria
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May you help me with my shunt? The output voltage stay on 4,59-4,60V and turning the pot doesn't affect it. Before this to happen, I had found out I had an error in my schematic. I had swapped the top BC550 with the 2SK170
http://i42.tinypic.com/33eo9jd.png. There was voltage regulation using the pot alright, but there was a voltage drop when changing the output load even if it was much bellow the dummy load.

The SK170 was heating very much in this case, depending on the dummy load. So I put both transistors back to the correct places and now there's no more voltage reg.
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Old 8th April 2012, 12:31 PM   #4939
Salas is offline Salas  Greece
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Verify your CCS current setting is enough to feed the load and allows some extra for the shunt to self feed too. At least +20mA. If that is not the problem check both Mosfets work by having 3.5-5V between their G & S pins on a meter. If no voltage, exchange. If healthy, exchange all TO-92s in case one of those is dead.
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Old 8th April 2012, 12:36 PM   #4940
50AE is offline 50AE  Bulgaria
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Thank you Salas for your fast reply! I will try and post results later.
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