Puff Valve Driving
The EHT Puff Valve Driver can drive four independent miniature high speed, high vacuum pulse valves at higher actuation speeds than is possible using the working voltage level of the valves. It works by quickly energizing the valve with 250 V for a short time of < 500 µs before providing an even 18 V “keep alive” voltage that holds the valve open at low power.
Pulse Amplifier driving two valves at 10 Hz repetition. The figure shows the internal energy storage capacitors voltage (yellow) reaches maximum voltage between shots, the output current (green), and the output voltage (blue).
The following figures were determined with a Parker 28 V 70 Ω pulse valve load.
- Charge Voltage: 0 – 250 V
- Output Voltage: 0 – 250 V
- Keep Alive Voltage: 18 V
- Max Repetition Frequency (HV disabled): 100 Hz
- Min Pulse Width†: 300 µs for full actuation
- HV Decay time (250 V to 18 V): 800 µs
† Min pulse width figure is gathered from Parker pulse valve datasheet. It is possible to partially open the valve with much smaller pulse time.