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.
From an article in Radio Electronics magazine, May 1989, this circuit requires a dual power...
We found this circuit in a 1967 Electronic design. However, it can be easily implemented even...
Old phones with dials can be used in a simple home intercom system, as this circuit from Popular...