High Voltage DC-DC Boost Converter 12V to 150V-420V 170V 230V & 1.25V-12V 6.3V Filament Adjustable Step Up Power Supply 2-Way PSU Regulator Module for Tube Preamp/Nixie Tube

As other commenters have said, the high voltage is completely unreliable - after setting it at about 300V unloaded, it drifted way down below 190V over time. Loading it made no difference. The heat sinked transistor is also super hot and I think the board has a massive thermal instability. Do not waste your money.

I like this. I am using this to power a small vacuum tube amp that I built for my guitar. I can not crank to full voltage but I can get it up to about 200 volts and it runs a little warm but is stable and does not introduce noise into the amp. This works much better than having to have a high voltage transformer etc. You can run this off 12v batteries and get off the grid and play a tube amp without heavy transformers etc.

Works Perfectly ! Coil must be glued by silicon!

Poor quality, four units tested. HV output does not meet stated spec 30-50mA. Overheats with light load 5mA.

really should work at 5 vdc , to be valuable. All these supplies need 12 vdc and tubes have 6.3 v . So 12 v is another power supply for a power supply . Might as well stay 60 hz Also USB is everywhere 5 vdc 2 amps . yet no 90-200 v supplies made Can this be modified for 5-7 vdc input

The high voltage circuit of this product does not work. When powered at the recommended 12 Volts, the output voltage was not stable, either with or without a 100 kOhm load. Its current draw from a 12 V supply started at 1.15 Amps at 233 Volts, dropped to 0.36 Amps, would fluctuate suddenly from 0.4 to 0.8 Amps. Thereafter, I could only adjust the voltage from 140 to 178 Volts. Again, the high voltage was not stable. The low voltage circuit of this product does work and is adjustable. I set it to mid-scale, 6.6 Volts.

Very good

I purchased one of these, and the filament voltage side on that one would not adjust down lower than the 12 v input. Output voltage adjusted just fine. Returning items to Amazon is a huge PITA because of my location, so I just ordered a second unit (while willing to suck up the cost of the first one). Second one arrived today, and it has the exact same problem - the filament voltage side will not adjust. It just remains stuck at the input voltage. (Again, the output B+ voltage side adjusts.) This time, with two of these to return, it's now worth the time and money to return both units for refunds. Shop around somewhere else to find one of these types of power units. Clearly these are just a waste of time and money. I'd give this ZERO stars, if that was possible.