This circuit was found in the February 1980 issue of Radio Electronics magazine. The digital circuit was shown in two parts, using 20 LEDs in a configuration with the LM3914.
This circuit with JFET was obtained in a book on FETs of 1989. The circuit is still current since...
This circuit was obtained from National Semiconductor documentation from the 1990s. The circuit has a...
Found in 90s documentation from Analog Devices, this circuit employs operational amplifiers of the time....