This circuit was found in an American medical documentation from 1970. The circuit rejects the 60 Hz noise pickup and generates 2.5 Hz signals. Equivalent components can be tested.
This simple circuit causes an LED to light up when the battery voltage drops below the voltage set in the...
Obtained from a 1967 documentation, this circuit uses transistors from the time. The galvanometer can be a...
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...