I have a standard glass pH probe connected to a Microchip MCP607 op amp which passes the signal to the A/D on a PIC16F877. The problem is that I have some stray voltage produced by high-output flourecent bulbs over an aquarium. When the lights are on and the pH probe is in the water the op amp output signal is 0V. When the lights are off the output signal is correct. When i place a ground probe in the tank with the pH probe and the lights are on I get a signal of 0V.
As soon as I turn the lights off everything goes back to normal. What's wrong with my circuit?
My op-amp circuit is the top circuit on the attachement.
thanks
As soon as I turn the lights off everything goes back to normal. What's wrong with my circuit?
My op-amp circuit is the top circuit on the attachement.
thanks