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.
This circuit is placed between the instrument pickup and the amplifier input. The same version can...
This circuit triggers on a lamp when the sensor (a metal plate us touched). Up to 100 W...
We obtained this circuit from a 1993 documentation. The circuit has current and voltage ranges that...