A pulse driver circuit designed for solenoids and coils generates a short pulse of predetermined width to activate the solenoid.

The second half of the talk goes into the specifics of writing a user space driver for these cards. Emphasis is put on how to correctly allocate memory for DMA and what happens to your file system ...

[Leo] looked at the WS2811 LED driver, but found that the ... the current and one to PWM the LED. The circuit he came up with is deceptively simple — just four transistors, a Schottky diode ...