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Author Topic: Hannah Ph electrode to arduino  (Read 2076 times)
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I have a Hannah Checker pH tester... however... it takes a LONG time to read. It will slowly go up. I know it's not the electrode because I took it to a local Hydroponics shop and the electrode worked great on another meter. Sooo.... I was wondering if it was possible to take the electrode and some how interface it with the arduino and print it out on a lcd screen along with tds and temp of the water. I am growing spinach hydroponically and I dont always have the time to go down and check my ph and tds. So I wanted to make this and then run it through cat5 line up stairs or even somehow get it on my pc through the wireless router.  Would these ideas even be possible and at a decent price?

Here is my pH meter:
http://www.hannainst.com/usa/prods2.cfm?id=002003&ProdCode=HI%2098103
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Not easily If all you own is the probe. If you have the whole meter and the measurements are changing but not on their (the AG Supply) meter than your probe is ok then the meter amplifier likely has a fault, PH measurements are not so very simple as they need temp comp among other things. PH or hydrogen ION measurements are heavily temperature dependent and all the Probes I ever worked with were isolated carefully from ground (the early ones (Laboratory Grade) were battery operated just for that reason) and the later versions are battery operated too but I think more for portability than function. Ph? for Spinach? what are you doing to your irrigation water besides pumping it around and periodically adding more water, and TDS...If your feeder dispenser is accurate every couple of days should be enough. In early 2000 or 2001 I was asked to develop a similar system for "Carrots"... new breed... Cannabis Sativa, don't you know. It seems the guy wanted turnkey setups to leave various places away from people... to grow 'carrots' and he knew that this was necessary hardware. Someone else built it for him(was really illegal in So Cal.) and he was apprehended 'reading the meter' as it were. Clever boy rented a warehouse in Arizona (Parker AZ.) right across the river and the warehouse was rented from the county...Poor Guy,Crossing a state line to commit a Federal Felony Offense (Cultivation of a schedule One, Federally controlled substance) is a very foolish thing to do. My opinion is likely useless as I retired in 2008 and Fet type PH sensors were just being sampled, they were Horribly Fragile both mechanically and electrically and as the 'gate' was the mechanically and electrically most sensitive part. Any leakage was out of the question and contact with solids (in my case soil). What do TDS have to do with proper nutrient chemical balance?... TDS would be the easiest to make and likely the least valuable.
For 20 years I was the design engineer for a company called RaValCo. WE made remote controlled irrigation actuators (wireless) and a line of soil moisture and conductivity measurement tool for the AG Industry.
Gratefully Retired now and Lovin my Uno.

Doc
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You might want to check this site
http://webpages.charter.net/tdsmeter/index.html
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While not the highest lab quality you can certainly interface pH probes even the IFET types. There are many examples on the net and having reverse engineered several commercial meters I can assure you some of the designs are are quite good actually, although more geared for our(OSHW or educational) usages then mass production. You can find out how to build a basic one http://www.sparkyswidgets.com/Projects/pHInterface.aspx and there are links to some other designs and app notes as well. With a little bit of patients and some guidance you should be able to have something reading this quite quickly, let us know how it goes.

Also yes Docedison even spinach, cabbage, tomatoes and strawberries(or whatever) need properly pH'd water with the right amount of fresh nutrients. Right now I have 2 spinach plants, 2 cabbage, a strawberry and a tomato, all in an high pressure aero "table" running off a 12v battery, an inverter and an arduino style controller board. So far so good on this experiment smiley
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Yeah but what I was getting to run around the bush about was the TDS function, the rest was just intended as fun, I apologize if you took any offense. There Certainly was NO offence intended.
I didn't understand the source of TDS as I thought you filtered the flow from collection to it's ultimate destination, certainly you would filter the growth medium after you mixed it and before you
pumped/poured it into your reservoir or holding tank so TDS?...

Doc
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TDS measures the amount of dissolved salts in the water.  In the case of nutrients and hydroponics it's nitrate and phosphate salts mostly.  It's used as a way of estimating the amount of fertilizer in the water.  Filtering water generally doesn't remove those types of salts unless you are talking about reverse osmosis or deionization.

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I always thought TDS means totally dissolved solids, not salts TDS has always been a measure of potable water purity, At least that was what it meant when I designed a series of  Conductivity/Moisture Probes for agricultural soil measurements. It was a neat little device that measured the effects if a small rf field from a coil in a sealed probe, my moisture meter measured another change and it was a sealed probe as well.

Doc
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Have a look to
http://atlas-scientific.com/index.html
They do good instruments at reasonably good price
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