This receiver was found in a Japanese publication in 1967. The circuit uses germanium transistors and details of the coils are not given. Power is supplied by a 9 V battery.
This circuit is from a Popular Electronics from the 90s. The circuit has a tone frequency...
This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose...
This circuit is based on a common cathode 7-segment display. The circuit is based on CMOS...