Does anyone know of a good compact pH preamplifier with an external DC supply? All of the ones I found have a lithium battery as the
source, but I can't use something with just 5yrs life. Also, I'm looking for something with a small form factor (around 3"x3").

The output can be mA, mV or V.

Thanks in advance to anyone who can help!!!

 

You probably realize that the pH probe itself won't last anything close to 5 years...

The preamplifier is often built into the pH transmitter, or can be remote mounted for long lead lengths. I'm not sure if you really mean
preamp or transmitter or both.

Anyway, one fairly economical unit is the GF Signet 2720 preamp and 8750 transmitter. The transmitter is 4-20mA loop powered, and it powers the preamp. These are designed to work only with the Signet pH sensors, I believe (2714 or 2715). Look at "http://www.gfsignet.com/products/index.html":http://www.gfsignet.com/products/index.html for details, spec sheets, and instruction manuals. The calibration routines built into the
transmitter are particularly good (read easy).

Hope that helps,
Eric M. Klintworth
Sharp Technologies, Inc.
Columbus, Ohio