This circuit uses an HA2400 consisting of 4 digitally controlled operational amplifiers. The circuit is from a Radio Electronics magazine from March 1980. The power supply must be symmetrical.
We found this circuit in an Electronic Engineering of the 90s. The circuit can be implemented with any...
This circuit from Radio Electronics from February 1983 shows how to use a clock radio in home...
This configuration with the LM111 was found in your factory manual. The circuit can be implemented with...