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Robo-Tank Isolated PH Circuit
#1
Well today was a good day, I'm happy to say I will have a PH circuit available in a week or two. I've been working on this a while and finally everything is looking good, now I just need to write some code for all the functions.

The circuit is fully isolated from anything else on the controller, the GND, power, SCL and SDA pins are all isloated using a high quality isolator. 

I've been doing tests comparing it to the Atlas PH circuit using a brand new low end probe. I have things setup so I just move the probe BNC from circuit to circuit. The Atlas circuit is connected to Robo-Tank and I have the new circuit running on a Mega 2560 for easy testing. 

Last night I mixed up a batch of 4.01 buffer so I had a true number to test with. The Atlas circuit settled at a rock solid 4.06 and this one I left overnight and it settled at a rock solid 4.01 all through the night. Now I wonder which one is truly correct, I have to go with Atlas just because but the buffer is 4.01 and that's what my circuit likes, hmmm....

I've also done some tests with different PH levels and the difference is always the same across the board so I'm sure once both circuits are calibrated to the probe they would be a perfect match.

The resolution is in thousands from .001 - 14.000, here's the last 10 readings.

4.011
4.011
4.013
4.012
4.011
4.012
4.014
4.013
4.012
4.012

To produce a reading it takes about 1.8 seconds, slightly slower than Atlas, I think that one takes 1.6 seconds. Everything is done on the circuit and values are sent to the controller so no load is on the controller, same as the Atlas.

Now I'm trying to get all the features nailed down , this is what I have so far, if anyone can think of something let me know.
  • Output PH and estimated CO2
  • Change I2C address
  • Save I2C address in eeprom
  • Temperature compensation
  • 1, 2 and 3 point calibration
  • Save calibration data
  • Clear calibration data
  • User can input KH value to generate estimated CO2 levels (once a real KH probe can be used that number can update circuit)
  • Save KH value
  • Circuit will calculate and track the slope (degradation) of the probe and report to controller so you can monitor probe condition.
Here's some pics. The board has a high quality OpAmp, processor, isolator, linear voltage regulator and a reverse polarity schottky diode and the PCB is 70mm x 30mm in size. The board can be connected to the controller using the USB ports on Gen3 hardware and the header pins can be used to connect to Gen2 or directly to any Arduino. The header pins can also be used to daisy chain multiple circuits together. You can use multiple PH and I hope to have a circuit for ORP and conductivity soon. 

[Image: pH_Front.jpg]

[Image: pH_Back.jpg]
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Messages In This Thread
Robo-Tank Isolated PH Circuit - by Rob F - 02-16-2019, 10:08 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 02-18-2019, 02:15 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-18-2019, 06:59 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-20-2019, 03:13 PM
RE: Robo-Tank Isolated PH Circuit - by whitbeox - 02-20-2019, 04:58 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-20-2019, 05:10 PM
RE: Robo-Tank Isolated PH Circuit - by aquaalgae - 02-20-2019, 06:52 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-20-2019, 10:02 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 02-21-2019, 03:02 AM
RE: Robo-Tank Isolated PH Circuit - by aquaalgae - 02-21-2019, 06:19 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-21-2019, 05:49 PM
RE: Robo-Tank Isolated PH Circuit - by aquaalgae - 02-22-2019, 08:53 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-22-2019, 09:53 AM
RE: Robo-Tank Isolated PH Circuit - by aquaalgae - 02-22-2019, 10:35 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-22-2019, 11:28 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 02-24-2019, 03:01 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-24-2019, 03:04 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 02-24-2019, 09:07 AM
RE: Robo-Tank Isolated PH Circuit - by vilich - 02-28-2019, 05:27 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 02-28-2019, 02:43 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-06-2019, 03:11 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-11-2019, 07:51 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-13-2019, 11:49 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-13-2019, 09:12 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-14-2019, 02:42 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-15-2019, 12:12 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-15-2019, 08:38 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-15-2019, 04:01 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-16-2019, 06:25 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-16-2019, 04:35 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-17-2019, 02:19 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-17-2019, 03:41 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-21-2019, 09:19 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-22-2019, 01:22 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-25-2019, 11:12 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-26-2019, 11:28 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-27-2019, 09:38 AM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 03-28-2019, 02:29 PM
RE: Robo-Tank Isolated PH Circuit - by rott - 03-31-2019, 10:28 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 03-31-2019, 05:33 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 04-09-2019, 11:07 AM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 04-09-2019, 12:41 PM
RE: Robo-Tank Isolated PH Circuit - by fietsenrex - 04-11-2019, 01:45 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 04-11-2019, 04:19 PM
RE: Robo-Tank Isolated PH Circuit - by jlysaght3 - 04-11-2019, 04:26 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 04-11-2019, 04:44 PM
RE: Robo-Tank Isolated PH Circuit - by jlysaght3 - 04-11-2019, 08:43 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 04-11-2019, 09:28 PM
RE: Robo-Tank Isolated PH Circuit - by jlysaght3 - 04-12-2019, 04:29 PM
RE: Robo-Tank Isolated PH Circuit - by Rob F - 04-12-2019, 05:47 PM

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