This circuit is from American documentation from the 1980s. The circuit can make use of any common NPN transistor and the power comes from two small batteries.
This simple circuit causes an LED to flash at times whose active cycle is determined by C1 and C2....
This circuit is temperature stabilized. Modern equivalent transistors can be used, and the power...
This simple circuit works at the same time as a radio receiver and transceiver for the medium wave...