PH Sensor

Kaos Kidd

I'm checking before I reinvent the wheel, if any one knows about a PH sensor (IE, checks the PH level in a fish tank for example.)· I know there's at least one out there, it's part of a product that electronically measures PH.· I need to duplicate this on my current BS2 project...


The project:· The FishMinder...· Monitors filter pressure/flow... PH level, temp and logs it... alerts via beeping speaker, hi/low conditions on each measurment.· It will feature a rolling log display on a LCD (buttons to move up or down in time, left / right for which measurement to display)... auto rollover at log max (when the log is full, it starts overwriting at the oldest entry...)·
Items to be interfaced... 4 buttons, 4 leds, speaker, LCD, real time clock, EEPROM, temp, a/d (for pressure) and what ever is needed for the PH sensor...· Drawings and details to follow, as I'm SURE as ALL I'll need to tap into all the smarts located here... [noparse]:)[/noparse])

Thanks All..

KK

Tracy Allen

I have a little writeup on measuring pH with the Stamp here:
www.emesys.com/OL2ph.htm

For long deployments in real world situations (e.g. fish tank vs lab beaker), I prefer the rugged sensorex electrodes.
www.sensorex.com/
One big thing you need to watch out for in real world apps with electrodes is interactions with other stuff in your tank. There can be all kinds of electromotive and galvanic currents that interfere with the pH measurement. Those problems can be resolved either by using an isolation amplifier, or by sampling (automatically?) the solution and testing its pH in isolation.

I've also measured pH using this RCtime helper circuit, with limitations:
www.emesys.com/BS2rct.htm#SmallV

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Tracy Allen
www.emesystems.com

Kaos Kidd

WOW...
Thanks Tracy...
Hmmm, a complete lesson included ... (one which I need as well)... I guess I got my hands on a tough one...
I liked the RCTime page link... very useful information to say the least...
As for the other lings, thanks so much...

I was thinking of puitting the sensor in the feed to the filter pipe or fitting in into the body of the filter (some place oppsite of the pressure sensor)
This way, the water would always be running, (keeping the sensor cleaner then if in the tank..)...
I haddent thought of isolating a sample then testing it.
Hmmmmmmm ... lots to think of on this...

Thanks again...
(It's time for me to call and make sure my BS2P40 will be here for Xmass.... !!)
KK