This double tone generator uses a specific integrated circuit, having been found in a 1977 CMOS Cookbook. The transistors can be the BC548.
This small MW transmitter emits its signals at a distance of a few tens of meters, depending on the...
This circuit, found in a 1988 documentation consisting of an audio switch that turns off the load...
This circuit was obtained in a 1960 transistor manual from Sylvania. The circuit uses small...