This circuit is from a 90's documentation. The circuit is simple, as it uses only two transistors, and the control is done by pressure switches. The indication is done by LEDs.
We found this common application of the 741 operational amplifier in a 1977 documentation. The...
This circuit, found in an old 1967 publication, cuts the current from a source when the current...
This LED bar graph circuit was found in the October 1980 issue of Radio Electronics magazine. The...