Simplistic MosFET HV Shunt Regs

[Salas]

I found 120K 2W 50ppm metal film but I suspect is inductive

WELWYN|MFP2-120K JI|RESISTOR, 2W 5% 120K | Farnell España

Don't know if there will be anything much to gain if non inductive, but low ppm is good to have since its a reference.

 

[dodo]

260-265V will suffice as minimum DC input to the 250V reg. 35mA will be enough for 16mA max load consumption. Make it 40mA if you can, its a bit better. CLC pre filtering and a good C2 or bypass, replacing the trimmer with a low ppm resistor after finding the value, a good C3 or bypass, a low ppm non inductive 120K Rref, short cabling to the load, that is about it.

I have used 2 x 242k Beyschlag PROFFESIONAL MBE0414 1W 50ppm with good results
But you have to buy a lot of them to find the same final rev after triming

 

[Salas]

Non inductive is welcome, low ppm is first priority IF decided to go best resistor parts. Still it works adequately with common parts. In what application you used the SSHV? Had good results?

 

[merlin el mago]

Don't know if there will be anything much to gain if non inductive, but low ppm is good to have since its a reference.

Other solution searching non inductive is Caddock MK132 0.75W in parallel 210K//287K = 1.5W 121K267, will be enough power?

 

[Salas]

Up to 250V the ref resitor(s) will dissipate 0.5W. I consider 3x choice as wise always. So 1.5W will be OK up to 250V and 2W for 300V for example.

 

[merlin el mago]

Are Vout of course?

For 2W Caddock MK132 4 resistors in parallel: 1 499K + 3 475K = 120K1952333 3W 50ppm

3 resistors in parallel 2W25 50ppm: 383K // 365K // 348K = 121K5915561

 

[Salas]

Yes. Vout. Must watch the permissible working voltage of the various resistors in HV applications too.

 

[merlin el mago]

Caddock MK132 are 400V/Max.

 

[merlin el mago]

I found 120K 2W 50ppm metal film but I suspect is inductive

WELWYN|MFP2-120K JI|RESISTOR, 2W 5% 120K | Farnell España

350V

 

[merlin el mago]

120K Vishay S106D 2W

http://www.texascomponents.com/pdf/vrths.pdf

500V

 

[merlin el mago]

Yes. Vout. Must watch the permissible working voltage of the various resistors in HV applications too.

 

[dvb projekt]

I try to get some Caddock Typ MS220/221

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[merlin el mago]

Excellent alternative: only one resistor TCR 50ppm tol. 1%, where do you buy?

 

[kacernator]

300V operation

Hi,

prior to my post of bad sounding Salas regulator, I had mistake in wiring, now it sounds very good. Anyway, my output target voltage is 300V. Is it ok to use schematics with MJE350 or should I go for schematics designed for more than 300V with 2N6520?

Thanks.

 

[merlin el mago]

Salas uses 2N6520, Quanghao uses MJE350 for all Vout changing some resistors values on his pcb, so if you intended to use Salas schematic I will put 2N6520 & if you will use Quanghao pcb you can use MJE350.

MJE350
VCBO 300V
VCEO 300V

2N6520
VCBO 350V
VCEO 350V

 

[kacernator]

So I should go with higher voltage version then. I cant buy 2N6520 in my country, but they do have BF493S (also 350V), so I hope it will work well as substitute.

 

[dvb projekt]

Excellent alternative: only one resistor TCR 50ppm tol. 1%, where do you buy?

That´s the problem. Nobody has them in stock. I try to get a quote from Caddock directly.

 

[merlin el mago]

That´s the problem. Nobody has them in stock. I try to get a quote from Caddock directly.

If possible count in me for 3 or 4 resistors?

I will ask a quote for Vishays, do you want to know the price?

 

[merlin el mago]

So I should go with higher voltage version then. I cant buy 2N6520 in my country, but they do have BF493S (also 350V), so I hope it will work well as substitute.

Mouser have on stock 2N6520

2N6520TA Fairchild Semiconductor Bipolar Small Signal

 

[pedefede]

heat on Q3

finished the positive part of my dual 300V supply for Exstata. Its P2p.

The heatsinks are a bit small (the ones for exstata's PSU), so the tempereture on the heatsinks stabilized after 15 minutes.
For irf9610 to 50 C, and for irf840 to 80C

(A bit high i guess. Adding bigger heatsinks is a problem in my chassis design, so i will add a fan. For test i just put up a 12'' PC-fan, and the tempereture fell to only 40 C

I also measured the V-out during warmup, and there was quite a nice linear correlation between V-out and tempereture of (the heatsink of) irf840. V-out raised roughly 0,5V per degree C. Is that normal??