This simple audio and RF signal tracker was found in a Japanese publication in 1967. The transistors are made of germanium and the headphone is made of crystal.
This circuit has been removed from the component's datasheet. In it we have a monostable or...
This light-controlled circuit uses a 6 V or 12 V relay depending on the supply. The transistor can be the...
In the figure a circuit that is the basic application of NE567 for the detection of a tone applied to...