Simplistic Mosfet HV Shunt Regs

[vgeorge]

Originally Posted by 10y

Depending on voltage output a nos az1 can supply about 100 mA at 300 V (philips datasheet)

So only two channels with one shunt possible.

[10y]

Originally Posted by vgeorge

So only two channels with one shunt possible.

Yes VGeorge,

at this point I will prefer to try a single dc raw with tx-rectifier-c-l-c line and after two shunt regs . I will see if my old az1 mesh will be sufficient strong on emission.

Cheers,
Anto

[albertli]

I placed my order to 'quanghao' for two boards and paid him through paypal over 2 weeks. I sent him couple email in between and tried to know when probably I'd have my two boards, but with no response. Please be warned not to send him any money before he clears this transaction.

[roger57]

He seems a bit slow in responding when I sent him emails. 2 weeks is a little soon, so be patient, our mail system, specifically Canada Customs, can be a little slow!
Let us know how the boards and operation turn out.

Gary

[kacernator]

Hi,

yesterday I had problem with Salas shunt reg. When I powered off the amp, something blew and smoked from regulator. It was working for two months without any problem so far.
This is my second experience with Salas reg that something suddenly blew off.
Version is "simpler simplistic Nov 09". Vin is 360V Vout is 290V.

It sounds superb, but i am now concerned with its reliability. I dont have gate protection zeners installed.
So I could install them and probably raise the gate stoppers to 330 Ohm?

Or does anyone know about other very good shunt reg design?

Thanks for advice.

[Salas]

Use the small Zeners on the gates anyway. Is there the MJE350 working near its Collector Emitter Vmax spec in your application?

[kacernator]

Originally Posted by Salas

Use the small Zeners on the gates anyway. Is there the MJE350 working near its Collector Emitter Vmax spec in your application?

Yes, the max spec of MJE350 is 300V and I am running it at 290V.

[Salas]

Don't know, that prototype of Nov2009 is still in service 315Vin,285Vout,40mA. Never blew. Has the gate Zeners non the less. HV, semis, and heat, are always potentially troublesome stuff on the other hand. Anyway, since higher Vmax PNP BJTs are hard to source, I will show you a bit later a schematic of how to cascode MJE350s for doubling their voltage spec and halving their dissipation. In general, keep it coolest temp possible and lower the Vin-Vo if you can. Sink the Jfet somehow with a little metal TO-92 winged cap or some improvised thing if its receiving some over 40C ambient heat from the sinks, its sensitive also.

[kacernator]

I cant find any substitutes for MJE350 for higher voltage in my country. What can I do?

[Salas]

You can cascode them, with this mod. That is one potential issue solving with this mod. It may well had been a transient that killed it or something.