$4 budget HV supplies - surprisingly good!

[drdn0]

Sharing these around because they are SUCH a bargain. Thanks to Grant from Valve Heaven for the heads up that these exist.

Cliffs: they are a budget Royer-style inverter that wiggles 12v DC to approximately 250vAC or around 360vDC (with a 1M bleeder load). Switching frequency is around 60khz, so out of the audio range - and the waveform is fairly sinusoidal so easy enough to filter. There is onboard rectification through FR207 diodes, so you have both AC and DC outputs available (refer to schematic).



There is a fair bit of ripple on the input, so I've added a 470uf electro + 0.1uf ceramic across the input pads which just required me moving one of the resistors over slightly so it would fit on the PCB. I've also removed the AC output cap, and used that area to mount the bleeder and initial output cap (22uf @ 400v).

It's not the neatest job in the world, but for a HV supply capable of running a STACK of tubes (including up to about 5w SE amps - and B+ only drops to about 260v with a constant 10w load) for under $10 I can't complain at all! I'd previously used the Nixie-style HV supply for tube preamp pedals, but given the cost + simplicity of these I think I know what I'll be using in the future.

[Krystal]

They're even cheaper than you said! 2.26€ (your link)