A little help please

[Instrument Resources of America]

I have a requirement for a small low power H.V. power supply and am
wondering if anyone here can point me in the right direction, since
almost all of you work 170 V plus supplies for the Nixie clocks. I have
a circuit that requires about 350 VDC, with some adjustment would be
nice, at a minimum of 5.8mA, I'd prefer to see 15mA perhaps even 20mA.
Size is not too important as it's not going into a clock or watch. It
does not even need to have a case on it, as I plan to mount it inside of
an existing piece of test gear. The input should be 120VAC 60HZ. I
assume that this is going to be some sort of switching regulator power
supply, which is good, since I do need to have the output isolated from
the A.C. line input. I tried Mouser and Ebay but perhaps I'm not looking
for it correctly.  A manufacturers name, and or part number, and where
to buy, any help would be appreciated,   Thanks,   Ira.

[gregebert]

I've done similar with a transformer with dual secondaries, each 60VAC (Triad F120-300). When you hook them in-series, it's an isolation transformer. Then, use a voltage-doubler and you have 340VDC. No need for switching supply.

I've also done hot supplies, without any isolation, and they work fine but you need to be very careful with proper insulation and safety measures. Stay away from this type of supply unless you have a lot of experience with power supply design. FWIW, my first nixie clock does this, and I have several that have been running for 11 years each.