This circuit is from General Electric documentation from 1970. The transistors can be of general-purpose types, except for the power that can be a BD136.
The circuit presented is based on a mechanical tuning fork. The circuit is suggested by National...
In this circuit of Texas Instruments an incandescent lamp is used as a light source, and lenses are...
One touch of the push button S1 and the circuit LEDs shown in the figure start to flash rapidly. The...