Hi,
I am using a 741CN op amp. I can only get the arduino to output from 353 to +753 when reading from the op amp. I find the limits by putting 5v to each input. If I put 5v and ground to the output, so the arduino is reading 5 and 0, then I get 0 and 1017 as limits, so I know the problem is not with the arduino. The voltage limit on the output of the op amp is 1.2 and 4.0 volts, no matter what voltage the inputs are seeing.
Any thoughts?
Thanks,
Can you describe what pins are hooked up to which other pins? Even a photograph of your current breadboard/prototype will help as long as all the connections are obvious. Failing that, a hand-drawn schematic could help, even better stick an Eagle schematic up on CircuitBee!
Look for chip that provides rail-to-rail output. 741 is not among them.
Example:
http://www.national.com/mpf/LM/LMC7111.html#Overview
The 741 is an ancient design, and needs split rail supply, many modern rail to rail opamps are way better.
The data sheet for the 741 says it requires a minimum of +/- 12V, that is a 24V split supply. You can't use it with 5V only.