The simplistic Salas low voltage shunt regulator

[dia thien thai]

Hi Salas and Ikoflexer !

I want use shal shunt for my DAC, out put +5v and -5v, but In my contry I dont fine 2SK170 and Bc550 in you cricuit Q2, Q5, Q6 = 2SK170, Q3 = BC550.
Aloso What transitor I can replaced 22SK170 and BC550???
Can you show for mee. Thank you very much
Dia thien thai
Best regarder

You can see in my cricuit

[ikoflexer]

Hi there dia thien, since it involves v1 perhaps you should listen to what salas will say when he wakes up

As a replacement for 2sk170 , can you find 2n3819 in your part of the world? If not, any n-channel jfet with an Idss of 6-10 mA can be made to work. As a replacement for bc550c, can you find 2n5088, or 2n4401? Ask your local electronics store for an NPN transistor with higher gain. That would be what I would try.

[Ryssen]

It is said not to use a capacitor at the output of a shuntregulator,what if the amp pcb,preamp pcb or similar contains elyts on the positive and negative rails to earth,should they be removed?

[Salas]

Originally Posted by dia thien thai

Hi Salas and Ikoflexer !

I want use shal shunt for my DAC, out put +5v and -5v, but In my contry I dont fine 2SK170 and Bc550 in you cricuit Q2, Q5, Q6 = 2SK170, Q3 = BC550.
Aloso What transitor I can replaced 22SK170 and BC550???
Can you show for mee. Thank you very much
Dia thien thai
Best regarder

You can see in my cricuit

Don't do it. To use a higher pinch off than -0.5V that the 2SK170 provides, takes to lift the Vbe margin with a resistor under the BC550. That will squeeze the voltage across a lot. The output Mosfet can measure 4V Vgs for instance. Use a transistor shunt.

[Salas]

Originally Posted by Ryssen

It is said not to use a capacitor at the output of a shuntregulator,what if the amp pcb,preamp pcb or similar contains elyts on the positive and negative rails to earth,should they be removed?

Those shunts here actually terminate with the recommended output capacitor. Its quality is audible indeed.
If you have further capacitors on the audio circuit PCB, you must see if they are part of local decoupling or R-C filtering before eliminating. If you are to remove some, don't remove the shunt's termination cap. Leave it there and use remote sensing nodes and wiring.

[Ryssen]

If you are to remove some,

Are there any disadvantages of keeping them there?Will the regulator oschilate with them?

[Salas]

Depends on inductance of wire in between and the actual job they do locally and in their ESR. They can help the sound or not, you have to listen with them and without them in the particular configuration you are going to arrive. But oscillation due to capacitors on the main circuit I haven't encountered yet.

[ikoflexer]

For those that built or will build one of these, something to keep in mind. The measured noise with the zener bypassed by a 100uF cap was between 400 and 500uV. With a 4700uF, the noise went down to less than 30uV, however, the inrush current for about 20 seconds was more than 1A. Just saying.

[Salas]

I have put up to 10000uF and I have seen benefits, it depends on the intrinsic noise of the Zener #number and its voltage range (12V ones seemed to be the quitest), but the instant current was too much and led to instabilities. I have settled to 1000uF and xxxxxxA type glass encapsulated Zeners. Which is a good compromise. TC compensated ones are the best but very expensive & not easily available to the diyer in no quantity purchace. As I have seen on FFT, the noise has a pink profile. It usually gives more robust bass subjectively than lowering hiss the better is filtered. Alternatively, LEDs can be used if the Vout asked is low enough to be tackled practically. There, 100-220uF is enough.

[maxpou]

Hi Salas,
if i put a gate stopper of 220 ohms in R2, it is correct? Thank you Maxpou

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