Found in a Popular Electronics from the 90s, this circuit activates a recorder for automatic recording of telephone calls. The circuit was used with old cassette recorders of the time.
This transformerless 16-ohm speaker circuit was found in a Radio Electronics from October 1963. The...
In the figure we have a solar power source for experiments with this type of energy. The cells must...
This circuit was found in a 1986 documentation and it may be difficult to obtain some of its...