This circuit decodes a 1800 Hz tone used in communications. The circuit is from an American documentation for radio amateurs of the 80's. Equivalent component can be used.
This circuit is interesting for experiments and can be part of the bench in the form of a module. The...
Constant currents from 10 mA to 1 A can supply the load, depending on the selection made by S1. Q1...
In the figure we have the transmitter and the receiver for an optical audio link via infrared. The...