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 found in a 90s Hands On Electronics. It monitors the presence of voltage in a...
This circuit for TTL probes uses a 7400 as the main element. The circuit memorizes the signal...
This circuit was obtained from a 1985 Electronic Desing. The circuit uses a Darlington which may be...