This filter is from a 1977 publication. The circuit employs three 741 or other operational amplifiers. The supply must be symmetrical and the components with (*) are low tolerance.
Found in a 90s Popular Electronics, this circuit keeps an LED on when a phone is in use. Can be...
This amplifier stage, obtained in a 1980 publication, has a low input impedance and a high output...
This circuit was found in an American magazine in 1976. It doubles the frequency of TTL signals in the...