I bought a set of x-ray equipment on eBay, which included an x-ray head unit, 50KV supply, and filament power supply. The filament supply has a 25-pin connector, and no data or markings on the case or board. I spent some time reverse-engineering the circuit, and determined how it should be connected to make an emission-controlled x-ray system. I tested the whole thing, and it appears to be working as intended at 50KV / 1 mA. The head unit produces a beam of about 25 degrees total angle.