Simplistic Mosfet HV Shunt Regs - Page 119 - diyAudio
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Old 13th September 2010, 07:19 PM   #1181
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Default Increase in HV

I use the Salas reg as in this schematic. Is it ok if I increase the Vin from 215V to 240V without doing anything to the regulator. As I see it the current draw will still be about 36mA. I have a big heatsink and the temperature is very nice today, about 40C I think.
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Old 13th September 2010, 08:01 PM   #1182
Salas is online now Salas  Greece
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Increasing the current to 50mA will bring you more benefit for lowering the Zo than just heating up the CCS Mosfet with more Vin-Vo since you got the sink.
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Old 15th September 2010, 11:26 PM   #1183
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Default bipolar 300v reg news

i ve been giving juice to my exstata (The eXStatA Electrostatic Amplifier) with my prototype bipolar salas reg for a handful of hours now and so far i have not noticed any sign of oscillation or malfunction and it sounds great (how surprising? ). in the meantime i ve been working on a final compact version but i cant make it work. but i highly suspect the problem comes from some kind of mishandling from me . i ll give updates when i try to debug it. as usual, pictures not available ...for now
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Old 15th September 2010, 11:51 PM   #1184
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So I must change that CCT's title from SSHV negative theoretical, to SSHV negative practical.
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Old 16th September 2010, 01:35 AM   #1185
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just to be sure i d put 99% practical and 1% theoritical
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Old 27th September 2010, 08:31 PM   #1186
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Hi Salas,

is there any issue wiring this P2P?

It's difficult to get a hold of QH for pcb.

for 40mA current, is 57.5ohms (1W) correct for R1?

5.4V(LED voltage) - 3.1(IRF9240) / 40mA?

the 1K trimmer is to adjust voltage? if my trafo is 230V into FWB, my
target voltage is 200-210V.

Is this HV shunt overkill for Aikido Cathode Follower? I'm using ACF w/6DJ8's.

which schematic should I be using? QH's schematic calls for IRF9610.

thanks!
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Old 27th September 2010, 08:53 PM   #1187
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No issue, I make it p2p only.

Current target is always ballpark for R1 given the Vgs of each Mosfet sample in circuit's actual voltage, and Leds total Vf. A check of R1's voltage drop across it divided by its value will give the real life current and will let you trim its exact needed value.

Looks like you will be dropping much voltage across the CCS Mosfet with a 230VAC Tx and 200V Vo. Use CRC and leave only 20V to drop. Saves on silicon's dissipation, increases long term reliability, pre filters.

In my experience its not overkill even if a good reg is there already (bypass it) or there is a good PSRR inherent scheme in the audio client CCT.

9610 proved reliable too and its the ''faster'' CCS choice. Don't forget to target about 25mA above your top load demand for setting CCS mA.

Regards.
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Old 27th September 2010, 09:14 PM   #1188
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Quote:
No issue, I make it p2p only.

Current target is always ballpark for R1 given the Vgs of each Mosfet sample in circuit's actual voltage, and Leds total Vf. A check of R1's voltage drop across it divided by its value will give the real life current and will let you trim its exact needed value.

Looks like you will be dropping much voltage across the CCS Mosfet with a 230VAC Tx and 200V Vo. Use CRC and leave only 20V to drop. Saves on silicon's dissipation, increases long term reliability, pre filters.

In my experience its not overkill even if a good reg is there already (bypass it) or there is a good PSRR inherent scheme in the audio client CCT.

9610 proved reliable too and its the ''faster'' CCS choice. Don't forget to target about 25mA above your top load demand for setting CCS mA.

Regards.
Thanks Salas.

actually I'm using the BAS PSU with 6xGT and CRC. So getting it to 220V
before the shunt is no problem.

the 6DJ8 pair is 20mA so I factor in the 20mA as you mentioned to double up or higher. I'm using a hammond 229 trafo, max rating is 230V @ 50mA.

is there a way to check for correct voltage/current without a load on the shunt?

Thx
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Old 27th September 2010, 09:19 PM   #1189
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Dummy load. 10K Ohm 10W. 20mA draw & 4W self dissipation if across 200V. It will be setting correctly for CCS mA and Vo without, but the dissipation for the load is going to add on the IRF840's sink.
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Old 29th September 2010, 12:50 AM   #1190
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should R1 and other resistors be 1% MF? or use 5% metal oxides for higher wattage?

I have a 10K 8W, should do the job for the dummy load.

thanks
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