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.
Found in an Elektor from the 90s, this circuit must be powered by an isolated power source and also...
The presented circuit makes use of a common operational amplifier that must be powered by a...
This high impedance step suggested by an English publication can operate up to 1 MHz with 1 V rms...