[Milsurplus] MOSFET High Voltage Regulator Circuit

[J. Forster]

There are two circuits with different names:

The Beta C Filter
and
The Emitter Follower

They are the same thing, if you just redraw them.  Either will work in the
application, although you might need to add a resistor and diode to limit
the load current on startup.

-John

================



> Mark,
>
> Basically, what you want is a "source follower" with the gate connected
> to a 200-volt shunt regulator made up of your two Zeners to ground, and
> an appropriate series resistor to +600.  Keep in mind that about 8 watts
> (400 V x 0.02 A) is going to turn into heat somewhere.  Personally, I'd
> do an "emitter follower" with a TV horizontal-output transistor.  Then
> the output voltage is predictable as one diode drop (base-emitter = 0.6
> volts) below the Zener voltage.
>
> Al
>
> Mack wrote:
>> Merry Christmas!
>>
>> I've almost completed my ARC-5 transmitter/receiver project but I have a
>> small amount of chirp when keying. I've confirmed it's the 200V I'm
>> feeding  to the oscillator plate not being stable. I can eliminate the
>> chirp by using my regulated bench HV supply.
>>
>> Please help with with a link or send me a schematic for a MOSFET HV
>> regulator that would work at 200V. I've looked about eight hours on
>> Google and nothing fruitful has developed. I'm looking for a simple
>> circuit with few parts. For example, could I just take a HV Power MOSFET
>> and bias the gate with two 100 volt zener diodes in series? The trouble
>> is I don't have a lot of experience designing with MOSFETS and I'm
>> really out of my league. I even tried SPICE but after two hours made
>> only a little progress with this complex program.
>>
>> The T-22 oscillator plate is 200V at 20 ma and it is only applied when
>> the code key is pressed and a relay is closed. The input to the
>> regulator circuit is the B+ for the plates of the 1625's at 550-600 VDC.
>> Therefore I need to drop from 600 VDC to 200 VDC at 20 ma and have
>> reasonable regulation.
>>
>> I know a much simpler and perhaps more authentic solution would be to
>> have two OC3's in series with an appropriate dropping resistor. However,
>> I may at some point want to have a circuit for higher regulated
>> voltages. I would also like to minimize the use of high wattage
>> resistors in the power supply with the resultant heat.
>>
>> Thanks as always for everyone's help. I'm really stuck on this one. BTW,
>> I restuffed all the bathtub caps in the transmitter and receiver and you
>> can barely notice they're not the originals. I'll post pictures of
>> everything once I'm finished.
>>
>> 73,
>>
>> Mack de WB4MAK
>> www.nfarl.org
>> www.sedxc.org
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>
> --
> Al Klase - N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
>
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