[Patrick Turner]

wrote:

Patrick Turner wrote:
One would have thought someone somewhere would have tried to make a
business
making SMPS capable of HV or at least 500V, which is only 1/2 a thousand
volts.

In fact there are lots of businesses doing this, but they are making
complexly synthesized voltages for large traction motors. Voltages are
in the range you are talking about, but currents in the thousands of
amps. Decades ago in fact they used tubes (thyristors, ignitrons).

At the very low currents the OP was asking about, it is hard to justify
a switcher when a small very-low-dollar 60Hz transformer does the job
(e.g. the AES P-T442 sounds like a perfect match.)

Tim.

If one only wants a few mA at +300V a voltage multiplier with ladder
diode
network will do fine.

+500V at 1A is not so easily done.

Patrick Turner.