This circuit is from Electronics Now magazine, February 1987. The number of channels is high depending only on the distances of the stations and the losses in the cables.
This small transmitter with 2 transistors can reach several hundred meters using a 30 to 70 cm...
This circuit was found in a Modern Electronics from 1990. It activates an old electromechanical pulse counter,...
Although the integrated used originally is uncommon today, more modern operating equivalents can...