This simple circuit causes an LED to flash at times whose active cycle is determined by C1 and C2. Transistors can be BC548.
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
Obtained in a 1968 Electronics World, this circuit uses transistors from the time and the sensor...
The basis of this circuit is a CA3130 operational amplifier. The transistor can be BC548, and the...