Hoping to use an Arduino to control a stepper motor that regulates a proportioning/needle valve that will give me constant tap water at 68- 70F for my black and white photo development. I want this unit to be self contained, by that I meen not using a PC other that uploading the software.
Will the Arduino have enough memory? If not how do you add on?
Source for appropriate steeper motors/ valves?
Has this application been tried that anyone knows?
Any positive criticisms and suggestions welcome.
Thanks
A gear motor may be the motor to use for this.
An Arduino would be able to handle this.
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Search for "proportional valve". They are expensive! I don't know if you can do it with a single "3-way" valve, or if you'll need two valves. You might also try a regular plumbing supplier... There are automatic shower temperature controls, although I don't know if you can set them that cool.
Will the Arduino have enough memory? If not how do you add on?
From what you've told us you don't need much memory. The program only has to decide "too hot", "too cold, or "just right".
Thanks for replies. What I'm gathering is that some commercial models(expensive) have the hot and cold water mix downstream as it is and the temperature is read there.
My thinking is that my cold water supply is always colder than what I need, so all I have to do is add some hot water to keep the water at the 68-70F coming out of the mixing chamber(pipe end). My problem is matching up a valve with a stepper motor and having the Arduino control it.
I believe the valve should be a needle valve that would give me that flow control required.
I have looked at shower temp controllers but are not that precise. I need to control + or - 1 degree hopefully.
Not being that familiar with code I thought that I'd need more memory that 32kb or so that the Arduino supplies. Guess I can deal with that later.
Any suggestions on type,voltage etc on stepper motor?
How about a water reservoir with a heater and recirculating pump?
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Hi,
Is this for a heater bath, or flowing water supply to wash negs and prints?
Tom... 
The water bath would be okay if there was extra room. I need a set up that is a flowing continuous supply that way it wouldn't be time dependent.
A rotamotor flow gauge on the cold line would establish the flow rate( about 1 gal/min).
I guess the overall question is how do I match up a stepper motor with a valve that the Arduino can control?