Ok, Im going to admit up front that this is a selfish request, but I think Im not alone in this quest. There are a lot of folks doing hydro of one form or another that could really benefit from an automatic PH controller, but they either cant afford to buy one, and/or dont have all the knowledge needed to build one from scratch.
Thats where Im at. Way too broke to buy one, but dont have all the knowledge I need to put one together. Im especially short on programming skills, but I also dont know enough about the various hardware options to trust myself to pick good (but cheap) hardware that would actually work at least somewhat reliably.
I have played around with Arduino some over the years in my RC hobby. I have an Uno, and have done some minor programming with it, but I really have no clue - especially on the programming. I hate programming and Im not good at it at all.
Here is where the selfish part comes in. I am sure I could spend the time to learn more about Arduino or other hardware options, and develop the programming skills needed, but thats going to take me a long time. I am no longer willing to spend that much time or effort for a one off project. Im just getting too old to learn all those new skills, and Im not interested enough in it to do it for fun.
So. Im hoping some of you, who do know this stuff, will be willing to contribute some of your valuable time and expertise to help with this project. I think it could benefit a bunch of people if we come up with a simple, inexpensive hardware list, and programming that other folks can do at home with some instruction.
I am thinking it would be good to keep this as KISS as possible. Mostly to save money. If a good setup can be designed, I think it would be easy to make small mods, with a different sensor, to do EC/TDS monitoring, and adjusting, or other automation. So a person could slowly add additional āmodulesā or parts to expand the automation as needed.
Here is what Im thinking might be a good, or at least cheap, start.
I see three basic parts needed.
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A PH sensor. I have no clue what would be a good/cheap one to start with that might last a while, and be reasonably accurate. Most people dont need to know the PH to .0001 resolution. Im good with .1 or so.
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You need a pump or valve that can add PH UP or DOWN as needed. I cant think of any cheap pump options, but a servo controlled valve would be very easy, and cheap to DIY. A set of 4 servos that would work fine can be had for $12 on Amazon. You could use them to pinch some tubing closed and open as needed. Simple and reliable. I happen to have a bunch of servos on hand and a Pololu servo controller.
Another option would be solenoids. There are cheap, plastic, 12 volt, zero pressure solenoids available for around $8 ea.
Both those options would require gravity feed, but Im ok with that to save money.
Some normal servos can be converted to continuous rotation, so it would be possible to DIY a peristaltic pump, but thats a lot more work. There are cheap peristaltic pumps available, but they have mostly crap reviews on Amazon.
The tricky part is what goes between the sensor and the servo, which is the third piece of the puzzle.
- You need a controller that can take the sensor output, and convert that to a signal that will control the servo, or solenoid.
It would be nice to have a USB connection to a computer to monitor PH and change settings on the controller for PH limits, and delays. Im thinking you need to have a delay after you add a dose to give the rez time to adjust, then re-dose as needed.
Of course, being able to monitor PH in real time and change the settings would be really nice. Maybe a USB connection to a laptop could work there?
It will be necessary to decide on servo control or solenoid control, because they need very different inputs to control them. The servo needs a PWM signal, and the solenoid needs 12V DC switched ON/OFF as needed.
I dont really have a preference between the two, but solenoid control seems like it would be simpler, and possibly cheaper - but thats just a guess on my part. I have no clue what is needed to generate/control a PWM signal that goes from hi to low or how to convert the sensor signal into something that can control a relay to switch 12 volt ON/OFF.
The Pololu servo controller I have can be controlled with TTL signals, but again, I have no clue on that either. It can be programmed to some degree, so you could send a signal to start a pre-programmed set of motions for the servo. For example, the signal inut could trigger the servo to move to the OPEN position, hold for how ever long you want, then close. That cycle could then have a built in delay before it repeats. That delay could allow the rez to adjust, which would remove the trigger signal from the sensor, and stop the dosing cycle.
Or, all that programming would need to be inside the Arduino controller itself. The Pololu would allow the controller to just monitor the sensor and trigger the dosing signal when a certain PH is reached and turn if off when the PH was in range. Without the Pololu, the Arduino would need to control the servo motion 100%.
Soā¦ anyone willing to help out, or have any other suggestions that would be cheaper or easier or better? You will be handsomely paid in good karma