Voltage sensor signal stability problem 2

[NASA1]

Dear All,
I am designing a voltage stablizier and had designed the circuit for it. However the voltage after LM324 IC is not a constant or stable value. It ramps up very slowly about 5 seconds and then sometimes go in the reverse direction. Ideally I would like it to ramp up ( if thats inevitable) quickly and stop on a steady value. Please see my circuit attached. The voltage sensor is the circuit beginning from 6v transformer
Many thanks in advance

 

[OperaHouse]

Why are you inverting the signal? Calculate the output with .1V input.

 

[ScottyUK]

What is the purpose of RV2 and RV4?

The input to U5:A is a filtered rectified signal. It will contain some 100Hz (120Hz) ripple. Are you hoping to use this as a reference signal? Use a zener or a reference generator IC as the reference instead.

You are trying to use an inverting amplifier to produce a negative output voltage from a single-ended supply. It won't work.


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If we learn from our mistakes I'm getting a great education!

 

[OperaHouse]

You probably wanted to have the bridge rectifier come out with a negative signal. The only reason you get a signal out of the op amp now is the chips input offset voltage.

 

[BrianG]

Not wishing to be picky, but why are your electrolytic capacitor symbols shown the wrong way round? Convention says the dark shaded side is the negative connection - if you actually have them back to front you could have heavy leakage currents such that the 7805 may be going into overcurrent limiting. This would make the +5v supply the cause of your "ramping" effect.