Signal conditioning

[hilmimohdmd]

Hi everyone. I'm now developing a monitorng system which monitors the pH level. I use NI-USB 6343 to acquire the analog signal from the pH sensor and it gave the signal in form of voltage. However, I need the signal to be in pH value instead of voltage. Thus, I'd googled and found that I'm required to do signal conditioning. After searching for some time, I found the basic step for signal conditioning but it just plain, basic theoretical notes on conditioning. Is the signal conditioning has something to do with MAX? do I have to tweak adjustments on MAX or just create a signal conditioning circuit on block diagram? Any helps are greatle appreciated.

[RTSLVU]

Is this a sensor you designed or purchased?

A purchased sensor should also include voltage/pH scaling factor, if not it is useless.

If this is something you designed then you will have to calibrate it yourself.

But either way the simplest method would be to use standard pH calibration solutions and correlate that to the voltage output of your sensor.

Then calculate the scaling factor, if you are lucky it will be linear, it not then you will need to do some mx+b type calculations. 

[johnsold]

Typical pH electrodes have very high source impedances. With those you may not be able to get accurate measurements with a conventional DAQ device. The signal conditioners used with pH sensors are specifically designed to accomodate the large source impedance.

Lynn