This circuit with a bargraph scale was found in a 90s Popular Electronics. The circuit measures the intensity of a sound in three scales. R14 works as a sensitivity adjustment.
This simple thermostat circuit was found in the September 1976 issue of Radio Electronics...
We found this circuit in the 1982 SGS Linear Integrated Circuits manual. The integrated circuit used...
This circuit uses a FET to drive an LED with constante currente. The current up to 20 mA can be...