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.
The critical components for this 1970s project are transformers. The original transistors are made...
Found in a 90s Popular Electronics, this circuit keeps an LED on when a phone is in use. Can be...
We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and...