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, suggested by an old American publication, allows you to use the AM radio antenna of a...
Powering from a 36 V supply this circuit has a power output of 16 W in 4 ohm loads. With 40 V and...
The circuit illustrated in Figure allows external loads (8) to be driven from parallel port...