LED Volt Meter Circuit LM324

Posted on Feb 6, 2014

It`s a very useful circuit which when installed on your car gives the voltage of you car battery in a LED dot display form. The meter circuit is based on four comparators made of quad op amp LM324. The inverting inputs of IC are kept at at reference voltages 5. 6V, 5. 2V, 4. 8V, 4. 4V respectively at pins 2, 6, 9, 13 by resistors, R3, R4, R5, R6. The battery vol

LED Volt Meter Circuit LM324
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tage is directly fed to the non inverting input through the voltage divider arrangement using R1 and R7. When there is variation in the input supply the out put of each op amp goes high accordingly as they are wired as voltage comparators. The corresponding LED glows. To setup, connect the circuit to battery, adjust R6 so that required voltages are available at the inverting pins( refer description to get the required voltages).

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