Using the LM358 from Texas Instruments, this circuit uses LED indicators and can be powered with voltages of 5V or according to the analyzed logic.
This circuit with the 741 operational amplifier was found in the March 1995 issue of Electronics Now...
This circuit was found in a General Electric documentation from 1966. It uses discrete components...
We found this circuit in a French technical documentation from 1982. The circuit can be...