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.
A touch in this circuit turns-on the lamp or the relay. Power supply is according the lamp or...
Found in a Popular Electronics from the 90's, this circuit uses integrated from that time, today...
This isolated shield for triac was found in old European documentation. The resistor R1, in fact,...