We found this circuit in the March 1999 issue of Electronics Now magazine. The indicator used is an analog type. The values indicated depend on the calibration.
The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply...
The circuit presented uses Linear Technology Operationals, having been found in a 1993 manual. The...
Found in American documentation from the 90s, this circuit triggers a buzzer with a Sonalert-type...