Using only one integrated circuit this control was found in an 80's Electronic Engineering. The circuit has the drive's logic information and must be powered by an isolated power source.
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...