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.
Found in General Electric documentation from the 1980s, this high speed perforated tape reader...
This circuit indicates when the voltage of a 12 V battery is low. With changes, for example, the...
We found this signal generator circuit in the November 1978 issue of Radio Electronics magazine. The...