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 simulation shows how a transistor can be used as a switch turning on and off in the LED. The...
This circuit was obtained in an English publication of 1975. It is a circuit that stabilizes an...
This is a common circuit in the 1990s, when experimental FM transmitters were in vogue. The...