In a September 1992 Radio Electronics article, we found this basic 555 circuit used to generate fixed times. Capacitor C1 and resistor R1 determine the time. The circuit drives an LED.
Using an operational amplifier with FET, this circuit was found in an English documentation from...
With the first project we present, a relay is activated in the presence of light. We can use it as...
This AC amplifier has a gain of 40 dB. It was found in the May 1988 issue of Radio Electronics magazine....