Using a 4046 PLL this circuit recognizes a 1.6 to 1.8 kHz tone by driving an output LED. The circuit is from a Radio Electronics from December 1989.
We can control the frequency of an oscillator from digital circuits or from the output of a...
We recommend adding a 470-ohm resistor in series with the potentiometer in this dimmer circuit...
We found this circuit for old tape recorders in the December 1972 Radio Electronics magazine. The...