pH Meter
Good Afternoon,
I am fairly new to the world of circuits and micro controllers and am looking for a little help if possible. I am trying to design a pH meter using the basic stamp. Right now I have my BOE as sort of a digital voltmeter using a POT and AD converter. I would like my input to be the pH of a solution and be able to continuously monitor it. Does anyone have any advice for me? Thanks so much
I am fairly new to the world of circuits and micro controllers and am looking for a little help if possible. I am trying to design a pH meter using the basic stamp. Right now I have my BOE as sort of a digital voltmeter using a POT and AD converter. I would like my input to be the pH of a solution and be able to continuously monitor it. Does anyone have any advice for me? Thanks so much
Comments
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- Stephen
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- Stephen
Here's a couple other links that may be helpful:
Depending on how accurate you want/need to get, the required circuit is not all that terrible, but it does take some finesse to minimize stray signals and interference. The signal coming from the probe is very weak, and it doesn't take much to make things fluctuate.
Again, depending on how well you care for the probe, and how accurate you need to be, recalibration is not all that big a deal. The "secret" is to make the electronics so that you can get things stable and "close" (as close as you can to optimal). Then use software for any "tweaking".
The other factor is temperature. There are a couple ways to do this, depending on what you're measuring, and again, how accurate you need to be. You can either make the compensation in software, or there are special resistors made specifically for this, and if you can get the resistor the same temperature as the liquid being measured, you're "good to go".
The other choice is to find a pH probe/system with a "conditioner" or "amplifier" built in. This takes away the worry of the above circuit, but can add significantly to the cost. Don't expect to find one for less than $100.
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John R.
Click here to see my Nomad Build Log
Post Edited (John R.) : 10/24/2009 8:38:00 PM GMT
You will also need and analog to digital converter. Again look here for info on the TLC2543.
The above PH circuit should work with most standard off the shelf PH probes.
Greg
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Tracy Allen
www.emesystems.com