Water-Cooling Kits as Temp. Control for Photography? 11
Katboy asks: "Hi, I have a project that I want to work on that some of you overclockers might be able to help me with. I'm an amateur photographer. I have a home darkroom, (not interested in going digital just yet) and I live in Texas, where the water temperature is usually a bit high for developing film. The method of using ice to contol water temperature is messy and irritates me, and I can't find a cooling system that I can afford that would be useful to me. So I need to build one that can produce a steady steam of water at about 69 degrees Fahrenheit. Some of the cooling kits from places such as waterchill.com and athlonoc.com look promising, but but I don't know how I might incorporate a thermostat into the setup... (this water will then go down the drain) Any insight would be appreciated." Now this is thinking out of the box. I like the idea of reusing water-cooling kits in such a manner. How difficult would it be to wire a thermometer to such a setup, and what other uses might you have for a device like this?
Obviously No Plumbers on Slashdot (Score:2)
Y'all are way over-engineering the problem.
Even when it is uber-hot in Florida (where I live), the ground temperature just a few feet below the surface is in the 70s. The reason the build houses in Arizona into the ground is that it is cool.
I haven't processed any film in years but it seems to me that 68-72 degress (F) for black and white is a good target. You should easily find that without digging too deep.
So, here is my cheap solution to your problem. Get 40 or 50 feet of copper pipe. Dig a vertical hole 10 to 20 feet deep by two feet wide more or less depending on just how hot your area gets. Put a couple loops of copper pipe in the hole. Run your water through the loop of copper tubing. Make sure that the tube above ground is insulated with the same foam stuff that is around your air conditioner line.
Out of pocket cost is going to be about a buck or so a foot all told by the time you figure in connectors and the like. The good news is that once you get it in the ground, there are no additional expenses unlike many of the other ideas mentioned that involve your electric bill.
As an added bonus, you'll also have a great earth ground system to tap into.
You might complain that there isn't enough water in 50 feet of pipe to do the job. I would disagree and suggest that you slow your wash cycle. Not only does high flow risk sliding off the emulsion, it is not needed and bad for the environment. A slow flow for a bit longer will do just fine and you'll have plenty of cool water.
InitZero
Re: Obviously No Plumbers on Slashdot (Score:2)
Yeah, wiring up a refridgeration unit to your water pan to cool the water is 'over-engineering', however digging a 15 foot deep hole in your yard to run copper tubing from inside your house into isn't. Not flaming, just pointing out a rather glaring inconsistency in your logic.
Humans have been digging holes since before there were humans. Refridgeration is a relatively new invention. It is far less of an engineering feat to dig a hole in my ever so huble opinion.
InitZero
Aquarium supplies (Score:2)
While not terribly common in use, there exists water chillers for use in aquaria. They're fairly accurate in terms of temperature control, as they're intended to keep fish alive -- many of which will simply die in the face of large temperature fluctuation.
They aren't cheap. $700-$1200, as sold at petwarehouse.com.
A less expensive, but geeky solution, which would certainly not be plug-and-play, might involve a small discarded fridge (easy to find for near nothing at college campuses across the US, right about now), some copper tubing, a pump, a resevoir, an electronic valve, a computer (running linux, of course), and some means of getting temperature data.
Or, dismantle the fridge. Use the guts to cool the water directly, recycle the thermostat to control temperature. Careful modification of the thermostat should allow fine control of on/off cycle times, and allow good temperature calibration. Some sort of resevoir (a large plastic bucket) might be ideal here, as well, to smooth out the transition between "cold" and "Texas" water. Also in the bucket, it might be good to have a small pump (an aquarium power head) to circulate the water, keeping it all at thermal equalibrium. A float valve (rescued from an old dishwasher, or from a toilet repair kit) will prevent it from overflowing. You'll have a few gallons of auto-cooled 69 degree water at your disposal at all times - and it might even stand up to continuous use, depending on how fast you go through water.
Re:Try this (Score:2)
A company named Rolf C Hagan makes a heater which is submersible and electronically controlled (ie, no metallic contacts to get welded together, arc, and be generally bothersome). It is ~$17 at petwarehouse.com (I'd link to them, but their URLs show no signs of being even vaguely static...), same as the "etchant" aquarium heater from Mouser.
The Hagan heater I have only shows adjustments to 93 degrees, so it might not be useful for color work. It -does- keep the temperature quite stable (within less than a degree), without adjustment, and has been doing so for years.
What to do... (Score:2)
First off, get a TEC heatsink system - cheap. I am going to be a nice guy and do your research for you, since you are a photo geek, and not an electronics one, probably (maybe you are - some photo geeks are greatly into the electronics side of things as well). So, first - purchase one of these [allelectronics.com] - All Electronics is a good company and I have never had a problem with an order through them.
Now, the heat sink would go on the outside of your holding tank of water (for a holding tank, use a large plastic drink cooler or something similar - or some kind of larger metal container - if metal, though, insulate it after attaching the TEC). The heatsink on this device that All Electronics sells is on the hot side. The smaller metal side is the cold side of the TEC. These units were originally meant for refrigerator coolers (in fact, if you wanted to spend a little money, you could go this route as well). You might want to mount a heatsink on the cold side (AKA a coldsink) as well, to increase the surface area of it to the water. Remember to seal the area around the holes on the tank with a good amount of silicone glue (aquarium sealant) to prevent leaks.
Now, you might find you can do without a thermostat - how? The TEC runs on about 5 to 14 VDC - and it should be pre-wired correctly for hot/cold side (call All Electronics and ask - they might even give you a data sheet or something - back of napkin type drawing) as shown in the photo - hot side on the heatsink, cold on the bare plate - but who knows, it may be reversed...
If you use a metal container for the water, you could make the metal container be the coldsink side, instead of a seperate heatsink. Now, since the voltage can be varied to run the cooler, you can select a temperature range (actually, you would be varying the input/output of the TEC) to run at. If you mount the TEC near the bottom of the container, convection may help you - or get a circulation pump (like a small fountain pump). Also, add a couple of fans to the hot side heatsink, to increase the amount of heat it can pump away - you may want to vector this heat to the outside of your darkroom (don't want your darkroom to get hot and raise the ambient temp). Or, if fans aren't enough, use a water block and water cooling through a radiator (in effect, doing partially what you originally intended, with the added addition of the peltier - however, it might be more trouble than it is worth)...
Put a thermometer in the tank, turn on the TEC to max voltage (hook it up to 12 volts, through a potentiometer or rheostat, to vary the voltage) (and optionally the circulation pump), and wait a few hours. Check the temperature - too cold? Lower the voltage of the TEC, check the temp again. Keep doing this until the needed temp is arrived at. You should be able to achieve up to a 20 degree drop in temp on the water this way. After you have gotten the temperature of the water where you want it, then leave the potentiometer/rheostat at that setting and check it again every day over a week, and note what the fluctuation is - if there is any. There may or may not be - and if there is, it may be fluctuating with the room temp, etc - but if you keep that constant, the water temp should be pretty constant as well.
If you need a thermostat, I believe Radio Shack (and others) sells an electronic one (RS Cat #910-4922 and temp probe 910-4917) that can switch a relay on and off at a set temperature. You can then use this relay to control the TEC.
I hope this helps - you should be able to do it all for less than $100.00 if you shop smart. If you need help with the electronics, ask around - maybe a friend or someone else can get it hooked up...
Worldcom [worldcom.com] - Generation Duh!
Might not help at all. (Score:2)
Re:Obviously No Plumbers on Slashdot (Score:1)
Try this (Score:1)
An off-the-shelf solution? (Score:2)
put the heatsink in a bucket of ice (Score:2)
If you have some way of monitoring the chemical bath temp and turning the CPU cooling pump on/off as required, this would work fine.
MadCow.
Re:Try this (Score:1)
It's not difficult to process color film, but it's very unhealthy. Take it to the lab and pay $3. Have you ever seen the stuff that photographers die from? Scary.
Art At Home [artathome.org]