Using the LM383 this circuit was found in a Popular Electronics from the 90s. The source must be 14V and the integrated circuits must have good heat sinks.
This is another practical idea found in a 1997 documentation. This circuit allows a DJ to change the...
This circuit uses two 4001 ports to drive a relay. The circuit is from Electronics Now magazine, July...
This circuit is based on an LM3900 transconductance operational amplifier, found in 1992...