This circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM backup battery. Resistor R1 determines the battery charge.
We found this simple operating tester 741 in a European publication in 1991. The circuit...
In this receiver the is formed by 80 turns of wire 28 or close in a ferrite rod. The handset is...
The use of a diac improves the performance of the two dimmers in the previous circuits. The...