I've breadboarded a differential integrator as on
http://www.ti.com/lit/an/sboa092a/sboa092a.pdf page 59. The integrator is relative to the negative supply of the opamp. It works great.
I have a really old fluorescent desk lap with an "on" button and an "off" button. Hold the on button for a while, let go to start the lamp. Press the off button to extinguish the lamp.
When I press the off button, the integrator drops to 2.something V if it was currently outputting more than that. Not quite as low as it can go (which is around 0.5.) A 100k resistor and the op-amp input leave one leg of the capacitor at a very noisy spot, but I was surprised that it had such a strong effect! Other noise sources (turning the lamp on, power cycling my other desk lamp, which is even noisier) don't cause the circuit to hiccup at all, so I suspect there are things happening that I don't understand. So far, I've tried putting ferrite beads on the resistor legs, but I haven't got very many other ideas... I think I don't know enough about what's wrong to do more than try random things.
Any tips how to mitigate this?