Electronics
Pulse Generation and Control
The pulse board is a simple MOSFET low-side switch with two analog feedback outputs and a PWM input. The PWM input is isolated by a high-speed optocoupler, while the two analog channels use HCNR201 linear optocouplers for isolation.
The pulse board itself is not the primary discharge generator. It is connected in front of a DPH8909, which it then drives. Alternatively, a DPM8605 can be used instead of the DPH8909, although it provides less voltage. Both options offer various communication capabilities. The TTL version is required. The motion board uses an isolated UART interface for communication with the device. This works very well, and voltage as well as maximum current can be adjusted via the touchscreen. The firmware fully handles the necessary control. Communication occurs at a transfer rate of 115.2k baud, which must be set before using it with the DPH (or DPM).
The user interface is provided via an ILI9341 touchscreen, which also integrates an SD card port for loading settings and GCodes. The built-in oscilloscope keeps the observer close to the sparks and provides invaluable information for process optimization.
Everything is housed compactly in a 3D-printed panel.
Future prospects
A 7" Waveshare display with an integrated ESP32 is planned for the future and will help reduce the UI load on the motion board.
The basic framework already looks very promising.
