Found in Popular Electronics from the 90s, this amplifier uses components from the time. The circuit has differential inputs.
This circuit uses two 4001 ports to drive a relay. The circuit is from Electronics Now magazine, July...
This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be...
We found this circuit in a publication of 1990. With the changes it can be mounted easily today....