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i'm on a roll... the kgsshv


kevin gilmore

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Nice work on the PS's Horio!

I llike to duck under the table with a voltage meter tied to the outputs when I first turn a new build on smile.png

EDIT: Just looking at the photos again, I can't tell if you have insulators mounted behind the output fets.

That doesn't sound like a half bad idea. smile.png

Regarding the output fets, I have the isolated version of the part (version FQPF8N80C). They are attached to the sinks without an isolation pad, as my understanding was they are already isolated. It would be good to know my assumption is way off here, before I plug it in. I am more of a builder than an electronics wiz.

Edited by Horio
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That doesn't sound like a half bad idea. smile.png

Regarding the output fets, I have the isolated version of the part (version FQPF8N80C). They are attached to the sinks without an isolation pad, as my understanding was they are already isolated. It would be good to know my assumption is way off here, before I plug it in. I am more of a builder than an electronics wiz.

No thermal interface material either?

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That doesn't sound like a half bad idea. smile.png

Regarding the output fets, I have the isolated version of the part (version FQPF8N80C). They are attached to the sinks without an isolation pad, as my understanding was they are already isolated. It would be good to know my assumption is way off here, before I plug it in. I am more of a builder than an electronics wiz.

They are electrically isolated. But you still need some kind of thermal interface.

So either the thermasil silicone impregnated things, or some thermal paste.

Same thing with the 2sc4686a output transistors, and the 2sa1968ls current sources.

the ixtp01n100d are NOT isolated, so they need the aluminum oxide washers.

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Nice one Horio, looking forward to hearing the outcome.

+1

I think I'll order the transformers in the next days to [/url=http://www.toroidy.pl/index.php?option=com_content&view=article&id=6&Itemid=7&lang=en]Toroidy. I asked for a budget of 4 trafos with these specs:

TS 150VA PRI: 2x 115V SEC:

> 1x450v @ 150mA.

> 1x450v @ 150mA.

> 15 - 0 - 15V @ 15VA.

They gave me a price of 61 euros per unit and I think it's a good option (the price of Avel Lindverg UK is 107 euros per transformer with the same specs).

I know I can use a secondaries with 100mA instead of 150 and 10VA instead of 15, but I'm not sure it's correct voltage in the secondary (2x450v). Can somebody confirm if these specs are correct for a 500v version?

-- o --

Rodrigo

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If someone would like to test them under a curve tracer I'd gladly drop a few in the mail to you for free. album here.

all you need to validate is a multimeter.

If you have a scope and a function generator, it's easier.

How?

Setup a circuit that varies Ib of the transistor. Stick some sort of resistor on the emitter. Stick the X channel on the emitter and the Y channel on the collector. Stick your function generator on the collector and DC bias the transistor and sweep Vce essentially. Stick the scope in XY mode. Capture the waveform. Change Ib, capture again. Repeat.

If you don't have a scope and a AC source? Well just manually plot the IV curve for a few values.

Edited by luvdunhill
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On The preliminary BOM in the board buy thread there is a slight mistake in the spreadsheet for the KGSSHV power supply

The BOM shows the 240K 2W resistors part No. 283-240K-RC as 2 per board. The quantity should be double i.e. 4 per board.

Also, there are 4 0.1uF/1000V caps on the power supply board. Only 3 in the BOM.

It also looks like there are 4 leds per amp board, and 3 listed on the BOM. D1, D2, D10 & D13.

Edited by wink
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So I powered up the Power supply, and I'm getting +/-450VDC. That would be great if I wasn't trying to go for +/-500VDC. I'm getting about 570V if I measure the Bias (before the 5M resistor) to the ground.

I've got a 550V string of zeners (200V + 200V + 150V) at D3, D4 and D5. Under no load, my SumR transformer secondaries are measuring about 520Vac. I have not populated the voltage multiplier parts, and I have soldered a wire at the bypass.

Any ideas of what I forgot to do?

Edited by Horio
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The zener voltages are fine. On the board there is a resistor string that is 440K - 440K - 20K. That is setup for 450V. If you want 500V it should be 490K - 490K - 20K.

It forms a voltage divide against the 10V reference so that the 490K - 20K junction should be 10V as well.

Good news is the supply is working fine, just need to change the setup a bit laugh.png

EDIT: This has to be done for both the positive and negative rails.

Edited by Kerry
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I knew it! I'm putting that correction into my BOM. Thanks!

Edit: Okay, the closest value I could find to 490k is 487k. So I guess that means +/-497V output on my supply. Or I guess I could substitute them with 511k+470k to get +/-500.5V output.

Edited by ujamerstand
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