This filter was found in a Texas Instruments manual based on an operational amplifier 741. Other operational can be used and, with the indicated components, the rejection frequency is 2 kHz.
This is a slightly different configuration of full-wave power control than we found in an old...
This 1-transistor timer was published in Radio Electronics magazine in December 1960. The circuit has...
This type of circuit is widely used in old cassette recorders and tape players, regulating the...