This simple circuit is a continuity test that, in addition to testing resistors, can also test other components. Power is provided by batteries and the LED can be of any color.
This circuit was found in the Intersil Databook. The integrated circuit used is uncommon today. R2 sets...
We find this circuit in a radio amateur publication of 1977. Its purpose is to measure the...
This circuit that can be used as a three-tone domestic bell has a traditional configuration that...