This bargraph circuit using LM3914 was found in the October 1980 Radio Electronics magazine. Note the use of a transistor to modify the response.
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....