Found in American documentation from the 1980s, this circuit has a throughput of 700 Hz and a flat response of 400 to 500 Hz, with crystals of 3 MHz. Crystals of 2 to 15 MHz can be used.
Old phones with dials can be used in a simple home intercom system, as this circuit from Popular...
This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit has a...
This simple circuit indicates if the polarity of a load is reversed when it is connected to a...