This circuit was found in an article in Electronics Now magazine from March 1997. The transistors are general purpose, and the indicator is a 1 mA full scale analog type.
This is the circuit for the HM-10ª, an instrument sold by Heathkit. The circuit is from a Radio...
This circuit indicates when the monitored voltage drops below the value determined by the divider...
This circuit, from a 1975 Motorola manual, uses a power Darlington transistor of the time. We can...