This circuit was found in a 90s Popular Electronics. With it, using a 4066, it is possible to control between 1 to 100 the gain of an operational amplifier like the 741.
Found in National Semiconductor documentation from the 1980s, this circuit can be implemented with...
This circuit was found in a 1968 EEE. The circuit makes use of logic gates of the time and can be...
We found this circuit in a publication on operational amplifiers from 1978. The circuit is made...