Simplistic Mosfet HV Shunt Regs - Page 2 - diyAudio
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Old 14th December 2008, 02:05 PM   #11
JC951t is offline JC951t  Taiwan
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Hi Salas,
Thanks for the reply. What about CLC after the reg ?
Would it cause oscillation & drag down the voltage ?
Also if higher current is require how can it be achieve ?

Many thanks
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Old 14th December 2008, 02:16 PM   #12
Salas is offline Salas  Greece
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Not after. It is totally noiseless as it is and you will ruin its transient advantages that way. It is already correctly terminated.
Before it is the right thing, so to pre filter noise passively up high.
Actually you can see a 10H frame choke in the left side of the PSU box pictured above. Part of an input CLC.

If you have read my previous directions, you will see that the constant current is defined by the total Led string voltage drop minus the Q1 Vgs divided by R1. For the IRFP9240, Vgs at such voltage conditions is about 3.1-3.2V. Measure the string Led in series with a 10k resistor using a 9V battery. Note their total voltage drop. Then I=(LedsVdrop-3.1)/R1. In practice it will deviate around that, but you are in the ballpark.
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Old 14th December 2008, 04:24 PM   #13
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Hi Salas,

This shuntreg looks pretty interesting and simple design; I’ll have a closer look to it later. It also looks as a very good candidate to the application we were talking about earlier, the 6V6 lineamp.

Cheers
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Old 14th December 2008, 04:34 PM   #14
Salas is offline Salas  Greece
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I already look for a nice looking big sink good for 30W so to make monoblock shunts at 100mA/350V for that. Should look funky on that shiny copper chassis.
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Old 14th December 2008, 09:38 PM   #15
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http://www.diyaudio.com/forums/attac...amp=1229193896

Hi Salas,

Very nice work. Exactly what I was looking for my tube preamp (on the works)

I have a question about the input,

How does one get 400V rectified and filtered? can you give an example?

I mean what transformer did you use?

Thanks
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Old 14th December 2008, 11:56 PM   #16
Salas is offline Salas  Greece
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300V secondary with full bridge UF4007 and some 450V capacitor will get you there. If you need more than 340V regulated use a -400V PNP transistor like KSP94.
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Old 15th December 2008, 06:21 AM   #17
Salas is offline Salas  Greece
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Quote:
Originally posted by chatziva
http://www.diyaudio.com/forums/attac...amp=1229193896
Exactly what I was looking for my tube preamp (on the works)
P.S. Is this the preamp you are talking about? If yes, the PSU examples that you see here are overkill for current, dissipation - heat sinking. So, I instruct you a tailor made power scaled schematic if I may. You can see it attached. A 230V 100mA transformer and 4X UF4007 arranged as a bridge rectifier feeding a 220uF/350V capacitor is all you need for Vin. Also 2X rudimentary 3W heat sinks like those they mount LM317T regulators on.
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Old 15th December 2008, 10:38 AM   #18
JC951t is offline JC951t  Taiwan
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Hi Salas,
Just wanted to confirm. Is V out taken at C3 ?
If so what is the wattage of resistor R6 assuming
if I built a 50ma version ?

Thanks
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Old 15th December 2008, 10:42 AM   #19
Stixx is offline Stixx  Germany
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Quote:
Is V out taken at C3 ?
No, I suppose Vout is taken above R6...
R6 and C3 are a Zobel element when I am reading this right.
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Old 15th December 2008, 10:57 AM   #20
Salas is offline Salas  Greece
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Quote:
Originally posted by JC951t
Hi Salas,
Just wanted to confirm. Is V out taken at C3 ?
If so what is the wattage of resistor R6 assuming
if I built a 50ma version ?

Thanks
Stixx is correct.

Also if there isn't any special Wattage need for R6, you can use 1/4W. C3 is a dead end for DC, so virtually no energy consumption on R6.
Together they form a Zobel terminal block that helps transient overshoot performance. See how it overshoots at IRF840's gate for current without the Zobel.
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