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Author Topic: PH Probe Op Amp help  (Read 6402 times)
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Hello – I was hoping some of you would be willing to look at a project I found that I want to integrate with my arduino. I think have everything in my cart at digikey but I'm not sure, I'm just learning how to read these diagrams so I have to ask.

I posted the links below anybody have the time to review my order and see if I missed anything to complete this build? I have a power supply and bread board but I'm just learning how to read these diagrams so I have to ask.


http://blea.ch/wiki/index.php/PH_Meter



Op Amp's (u1a & u1b)
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-1281-5-ND
100k RESISTOR(Slope Adj. v1)
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=OD104JE-ND
R1
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=5.1H-ND
R2
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=OD392JE-ND
R3 & R4 & R6
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=22KH-ND
R5
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=12KH-ND

Charlie
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i'm not expert on coding the arduino but do you mean that we can connect a pH or ORP electrod to the arduino and read the value on a browser for example?
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For the op amp you have ordered the surface mount part. This will be hard to cope with especially for a beginner.

You need the DIL (Dual In Line) package at 0.1 inch pitch version of this chip.
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Hey Mike! Thanks for looking over the parts for me. I am def in need of the easier to solder DIP 8 module I'm glad you caught that!

This is the one you would recommend?

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-1771-5-ND

ata - This thing should let us connect a standard PH probe like with a BNC connector

http://www.marinedepot.com/ps_ViewItem~action~view~idProduct~AM1411~idCategory~FITERPPH~category~pH-Replacement_Probes-Testing_Equipment-Saltwater_Aquarium_Supplies~vendor~.html

and read it as 0-5v's or the circuit above shows that it can also be wired up to display 0-14v's for going to a voltmeter or cheap voltmeter display.

This will still require code to calibrate the device, which will take me forever because of all the other projects I'm working through at the moment. If someone else wants to get involved to help speed this up I might be able to lend out the hardware if it actually works….


Thanks

Charlie
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If you are looking for a fast and easy solution : a reasonably cheap alternative that allows immediate interfacing between Arduino and pH probe is the http://www.phidgets.com/products.php?product_id=1130 costs 30$ and has ideal inverted signal, 525mV offset and 4.75 gain. I have to admit: I tried the self-build option and failed.
This phidget has good gain which allows for more precise A/D conversions by the Arduino. Other interfaces (Vernier) only have 2.2 gain, resulting in larger margins of error.
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Hi pubdc,

I'm also considering pH/ORP adapter from phidgets.
Do you have any code and wiring diagram for connecting this to arduino?

Thanky in advance
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