This simple neon lamp oscillator produces a 140 Hz, 40 V peak-to-peak signal. The frequency is given by the capacitor that can have its value changed. Note the high supply voltage.
This circuit, which appears from other sources on this site, converts a voltage into a current....
This dimmer constrols the temperature of a wire used to print images in wood or other materials....
Found in a 2005 Linear Technology application manual, this circuit provides 12-bit resolution output...