Found in the American 73 magazine for radio amateurs, this circuit can test common quartz crystals. The circuit includes the power supply.
The energy that powers this radio's amplifier circuit is obtained from the signal itself. The coil...
Based on the BA1404 integrated circuit, this circuit was found in the July 1992 issue of Radio...
This circuit can linearly control the temperature of showers, taps or heaters up to 2 500 W. The...