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.
This circuit can generate audio signals at frequencies ranging from 0.01 Hz to approximately 20...
This astable multivibrator is one of the many configurations that we have in this section and on...
This circuit is an application for an operational amplifier with field effect transistors from...