Simplistic Mosfet HV Shunt Regs - Page 13

Salas · 15th February 2009, 10:59 AM

Milen:

They look OK for the moderate cuurent and voltage difference you gonna use. Put thermal grease for the surfaces to contact well. The aluminum looks rough.

JC951t · 15th February 2009, 11:19 AM

Hi Gary,
You missed out Q1

milen007 · 15th February 2009, 02:44 PM

Quote:

Originally posted by salas
Milen:

They look OK for the moderate cuurent and voltage difference you gonna use. Put thermal grease for the surfaces to contact well. The aluminum looks rough.

hi Salas

yep the aluminium is rough. i cut them into half myself. lol. they are cheap. they small one on the back of the irfp9240 is just around 15cents.

thermal grease? does the drain of the mosfet need to be isolated from the heatsink?

Quote:

Originally posted by JC951t
Hi Gary,
You missed out Q1

i think its there on the top left conner. just not labelled. Gary?

erwin

Salas · 15th February 2009, 02:49 PM

If the 2 Mosfet heatsinks are separate, and no one of them will ever touch ground, you can not isolate them, but if you touch them they will be on high voltage. Since there is always chance for an accident, I would highly recommend you use mica spacer pads and thermal grease, plus isolated screw for 840, 9240 normally has isolated screw eye. Best of luck with your project, let us know more when ready and listening.

Marinos · 12th March 2009, 09:23 PM

Hi salas,

I would like to try your regulator in a a low voltage triode line stage. The target voltage is 90 Volts.

Could this be done with simple changes to the schematic at post #2 or use the schematic as is and drop the voltage to 90 volts using an RC ?

Your advice will be much appreciated

Salas · 12th March 2009, 10:06 PM

Quote:

Originally posted by Marinos
Hi salas,

I would like to try your regulator in a a low voltage triode line stage. The target voltage is 90 Volts.

Could this be done with simple changes to the schematic at post #2 or use the schematic as is and drop the voltage to 90 volts using an RC ?

Your advice will be much appreciated

What is the bias current?

Marinos · 12th March 2009, 10:09 PM

55 ma aprox. for both channels

Salas · 12th March 2009, 10:15 PM

Set the 100R trimmer at about half before firing the shunt up. After half an hour of thermal stabilization, set for 90V and forget. Happy listening.

Marinos · 12th March 2009, 10:18 PM

God you are fast... Thanks a lot

Salas · 12th March 2009, 10:22 PM

No big deal. Let us know your impressions.

12th March 2009, 09:23 PM	#125
Marinos diyAudio Member Join Date: Mar 2003 Location: Athens	Hi salas, I would like to try your regulator in a a low voltage triode line stage. The target voltage is 90 Volts. Could this be done with simple changes to the schematic at post #2 or use the schematic as is and drop the voltage to 90 volts using an RC ? Your advice will be much appreciated __________________ Marinos

12th March 2009, 10:09 PM	#127
Marinos diyAudio Member Join Date: Mar 2003 Location: Athens	55 ma aprox. for both channels __________________ Marinos

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15th February 2009, 10:59 AM	#121
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Milen: They look OK for the moderate cuurent and voltage difference you gonna use. Put thermal grease for the surfaces to contact well. The aluminum looks rough.

15th February 2009, 11:19 AM	#122
JC951t diyAudio Member Join Date: Sep 2006	Hi Gary, You missed out Q1

15th February 2009, 02:49 PM	#124
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	If the 2 Mosfet heatsinks are separate, and no one of them will ever touch ground, you can not isolate them, but if you touch them they will be on high voltage. Since there is always chance for an accident, I would highly recommend you use mica spacer pads and thermal grease, plus isolated screw for 840, 9240 normally has isolated screw eye. Best of luck with your project, let us know more when ready and listening.

12th March 2009, 10:18 PM	#129
Marinos diyAudio Member Join Date: Mar 2003 Location: Athens	God you are fast... Thanks a lot

12th March 2009, 10:22 PM	#130
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	No big deal. Let us know your impressions.

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