This transmitter for the 3.5 and 7 MHz ham radio was found in a 1950s Japan publication. No information was given on the coils and the power supply.
This circuit produces a 2 kHz tone on a standard piezoelectric transducer. The circuit can be used as...
This CMOS integrated alarm was found in the July 1992 Radio Electronics magazine. The circuit has...
This indicator for audio signals uses only 3 components. LEDs are common and the audio signal with...