Found in a documentation from the 90's, this circuit uses only one integrated circuit. The resistors in series with the LEDs depend on the power that can be between 5 and 12 V.
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...