Based on the LF256 operational amplifier, this circuit was found in the September 1989 issue of Radio Electronics magazine. The indicator is analog, and the power supply must be symmetrical.
This circuit uses a 7812 and another regulator integrated circuit that is not very common...
The project is from a 1992 publication, but totally current by the components it uses. The LEDs...
We have a simple and useful circuit found in a 1982 documentation which generates a signal in the...