OP amp output not changing ( schematics )


This is a image of most of part of my circuit (555 timer IC is cut from right side)… enter image description here
using the pot (RV1) , I change the non inverting input voltages of the op amps. when non inverting exceeds inverting voltages of the op amps (which is different for different op amps) is should output 5V which should take BJT at saturation. Then current will flow from pin 7 to 6 in timer IC. But as you can see from the picture, though non inverting voltage is higher then inverting voltages output op amp voltage is still low.

why this is happening ??

again if I increase non inverting voltage a little from this value, LED start to blink (555 timer start operating) but still op amp output remain low .

enter image description here

**why this is happening ?

what can I do to made op amp work properly ??**


Best Answer

The LM324 has an input common mode range of the negative rail up to two volts below the positive rail.

So with a five volt supply, you need to make sure your signals are in the 0-3 volt range for proper operation.

In no case should you apply a signal beyond the supply rails to the opamp's input, like 6.1 volts into a 5 volt-powered opamp.