This simple logic level tester was found in Radio Electronics from the 90s. The inverters are of the 4009 type and the power comes from the circuit being analyzed.
The simple touch of the fingers on a sensor causes this circuit to drive a motor that goes into...
This simple circuit found in an American 80's documentation simply blames if there are toxic gases in...
This circuit is from Motorola's 1990 Linear Databook. The transistors allow equivalents and the...