We found this circuit in a 1965 Electronic Design. The transistors are from the era, and modern equivalents can be tried out.
The purpose of this circuit is to monitor the output voltage of a power supply. The under and over...
Old multimeters used a 22.5 V battery for high resistance measurements. If you have one, you...
In the figure we show a monostable that uses two of the four ports available on 4001. The duration of...