Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
This circuit was obtained from Signetics documentation from the 1980s. The circuit can be...
This circuit was found in an American 1980s documentation. The transistors admit equivalents and the...
This circuit controls a relay causing it to open and close its contacts at a speed that depends on the...