Some time ago I found on eBay a couple of HV generator modules made by FuG Elektronik GmbH, model HCN 20 EM-2000. These modules can be easily modified to be used as variable HV power supplies.
Quick fact sheet with pinout: 13822-01doc
- Positive HV output
- Variable output up to 2000 V
- Maximum output current 10 mA with overcurrent protection
- 31-pin back connector
- 24 V DC supply
- 5 kΩ linear multiturn potentiometer for voltage selection
- 0–10 V output voltage monitor (10 V = 2000 V out)
- 0–10 V output current monitor (10 V = 10 mA out)
The modification consists of re-housing the module, adding a 24 V supply and an Arduino-driven LCD to display voltage and current.
I started by removing the original aluminium case and putting all the electronics into a tabletop ABS enclosure with handle. On the front panel I mounted the LCD, a 5 kΩ potentiometer knob, and an SHV HV output connector. On the back panel I added a fuse holder, power switch, and IEC mains socket.
The HV output is further filtered by an R–C–R–C–R stage to reduce ripple and switching noise. For resistors I recommend 100 kΩ / 1 W types, and for capacitors as much capacitance as possible in the 10–100 nF range, rated above 2000 V.
In the picture you can clearly see:
- The Arduino protoboard driving the LCD
- The toroidal transformer providing 18 Vac → 24 Vdc after rectification and filtering
- The large black 5 kΩ “Helipot” 11-turn trimmer under the LCD (extremely precise—worth buying even at ~20 €)
The current and voltage monitor outputs are read by Arduino analog inputs through voltage dividers. These scale the 0–10 V monitor outputs down by a factor of 2 to fit within the Arduino’s 0–5 V input range. A small capacitor (nF range) is placed in parallel with the lower resistor to ground, smoothing ADC readings and adding some hysteresis.
Arduino code (self-explanatory): 2kv hv
Original PSU module schematic: 13822-01
Connections:
- 5 kΩ pot: pin (26) +10 V (29), wiper (24), GND
- (1–2) GND, (3–4) +24 V input
- (8) V-Mon output 0–10 V
- (10) I-Mon output 0–10 V