This circuit was found in old documentation, however the components used are common today. The selection of times is done by switch and the 556 consists of a double 555.
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
This circuit for decoding QUAM AM stereo signals, a system that was little developed, was found in the...
Found in National Semiconductor documentation from the 1990s, this circuit produces a tone to be...