This crystal or galena radio is one of the many versions available on this website. This is from a documentation from the 70s. The coil is formed by 50 + 50 turns of wire 28 in a ferrite rod.
This circuit consists of two stages that each shift 180 degrees the signal. The circuit was...
This simple battery tester uses two transistors to drive LEDs of different colors, indicating the...
Found in 90s documentation from Analog Devices, this circuit employs operational amplifiers of the time....