# DIY PH Regulator



## awohld (Dec 11, 2005)

Has anyone made a DIY PH Regulator.

Where can you get cheap PH sensors?

Hook up the PH sensor to a micro controller and connect that to control the CO2 solenoid.

You might be able to make a PH controller for the cost of the sensor plus $20 to $50. Maybe even cheaper if you use a PIC micro controller.


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## simonbrown403 (Sep 3, 2005)

Not as easy as that, you need a chip to program, so it knows when to turn the solenoid on and off.
I think you would have to be a bit of and electroin wiss to do it.


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## awohld (Dec 11, 2005)

I might take this as a challenge. I ordered my Milwaukee regulator.


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## dMenace (Dec 25, 2005)

Please give us the details of your success/problems!

Good luck!


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## sayembara (Dec 13, 2005)

Good luck. This is clearly an advanced skill. Look forward for news from you.


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## ruben (Aug 11, 2004)

Try this, I did one and it worked, it is expensive but I enjoyed (and learn) a lot,this a good translation, as the article says you can contact the autor in Spain. Good Luck http://www.simplydiscus.com/forum/showthread.php?t=33368


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## awohld (Dec 11, 2005)

I just got the IC chips yesterday to receive the signal form the PH sensor. Now I need the PH sensor, Amazon.com has some for $30 some dollars.

I have the microcontroller for the project and the vaccume flourecent display. I'd like to computerize my lights with dimming but that might not happen, I'm not sure where to get them. Any idea what would happen if you simulated seansonailty? Would some plants act differently?

It would be cool to have all the PH data stored on a server where you can monitor and trend it remotely. I tried to get some free sensors from a sensor company for O2/CO2/Nitrates/Nitrides but they weren't intrested unless I was using their data logging software.


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## dennis (Mar 1, 2004)

I don't have time to look it up righ tnow, but there are some posts by bluesboy regardingthis. He did alot of pH data storing, charting, Co2 usage, etc. If you search for posts by him you should find some pretty cool info.


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## BluesBoy (Jul 2, 2004)

> Has anyone made a DIY PH Regulator.


Sure! More than one - It's fun ;-)



> You might be able to make a PH controller for the cost of the sensor plus $20 to $50. Maybe even cheaper if you use a PIC micro controller.


The first shot was focused on cost (low-budget) and the solution was this:
I bought a timer unit at a local store and replaced the original PCB with an experimental board fitted with a $2 8-bit micro controller (Freescale) and some peripheral circuits:
http://www.bluesboy.se/viewimage.php?id=205
http://www.bluesboy.se/viewimage.php?id=209

It was working great as a controller in my planted tank but after a while I wanted to put a lot more features into the unit. Unit number two was focused on "high-tech" and was built up around a 16 bit $10 micro controller (Freescale) and a graphical user interface (LCD):
http://www.bluesboy.se/viewimage.php?id=355

Unit number three was a mix (low-end & high-end) with the high-end controller board and a cheep 16 character display. Total cost about $50 plus probe/sensor.

I'm currently using unit number three and it's working great. It has some features like: two relay outputs for light control, temperature measuring, two pH-probe inputs, electrical conductivity measuring and some great logging functions. For data analyzis I developed a PC program which can download/upload data to/from the controller. The result can for instance be a 24-h plot:
http://www.bluesboy.se/fotoarchive.php?album=Plottar

Good luck awohld! Go for it J


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## NE (Dec 10, 2004)

I guess one of the hard things to get really good is the pre-stage for the probe as it has to be very high in impedance.
It's quite easy to get strange behaviors because of potential (voltage) differences.


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## BluesBoy (Jul 2, 2004)

> I guess one of the hard things to get really good is the pre-stage for the probe as it has to be very high in impedance.


Well, it's not a hard thing but you're right - you must consider the impedance. Select an op-amp with very high impedance.
Another thing to consider is the dual output voltage from the probe (+- 59 mV / pH). I have designed an offset voltage to the ground signal of the probe wich rises the output signal to positive only (and amplifies it). This signal fits a controller A/D-input perfectly (0-5 V). I also prefere a quite long time constant of the input signal due to the slow behaviour in a tank. I use a R/C link for this and as a protection of the probe. The disadvange from this is the calibration time is extended some time.


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## simonbrown403 (Sep 3, 2005)

simonbrown403 said:


> Not as easy as that, you need a chip to program, so it knows when to turn the solenoid on and off.
> I think you would have to be a bit of and electroin wiss to do it.


I seam tobe eating my words lol, hows it going


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