Battery condition indicator

Posted on May 30, 2012

A 741 op amp is employed as a voltage comparator. The noninverting input is connected to zener reference source. Reference voltage is 5V. R2 is adjusted so that the voltage at the inverting input is half the supply voltage. When supply is higher than 10V, the LED will not light. When the supply falls just fractionally below the 10V level, the IC inverting input will be slightly negative of the noninverting input, and the output will swing fully positive

Battery condition indicator
Click here to download the full size of the above Circuit.

The LED will light, indicating that the supply voltage has fallen to the preset threshold level. The LED can be made to light at other voltages by adjusting R2.

Leave Comment

characters left:

New Circuits



Popular Circuits

Electrical Appliance Time Controller
PCB Exposure Box with Countdown timer (ATMEGA8)
High impedance DC Voltmeter by IC CA313048
5 Watt Class-A Audio Amplifier Circuit diagram
universal battery charger schematic
buzzer only beep once
The K9AY receiving loop antenna
Q-Switch Driver