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  1. #31
    olleorama's Avatar
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    Quote Originally Posted by Diapositivo View Post
    That's very interesting, but very challenging for the DIY-challenged like me. I looked on search engines for PID-thermostat, PT100 sensor, I get what you mean, but how do one assemble all those things?

    A PID-thermostat is something that controls boilers. How do I connect it to a heating element?
    A PT100 sensor is shown (the one I found) with some kind of a round connector. How do I connect it to the PID-thermostat? Is the thermostat voltage-dependant? Do I need to earth some of the above?

    Is there somewhere (maybe here on APUG, or somewhere else) a "dummy guide" that specifies exactly what one must look for (without margin for buying errors) and how to connect all the pieces, without margins for fires and shortcircuits? A guide that lets you go to the home-improvement store with a list of things to buy, and lets you assemble them at home, unfailingly well?

    Things that look easy for those who know, look mysterious for those who don't know, you know
    It's not really that hard. My pid-thermostat had screwconnectors for all cables. All you need is cable stripper pliers (or a knife/scissors) and a small screwdriver. But my thermostat is not chinese, so I don't know how to hook those up, some of them need an external relay, mine has an internal relay. I can take some pics in the morning if you like. The things you need aren't found in a home-improvement store though, I'm afraid. Well, maybe you can find a cooler that you can use.

    The ebaystore mixtea has sensors, SSRs and thermostats. The sensor is easy to hook-up, just remember to use shielded cable if you need to extend the cables. The thermostats he sells must be used with a relay, use a solid state one (SSR). There is a pdf on sestos site which tells you which terminals to use.

    Basically you screw or solder the SSR (solid state relay) on to two terminals, your mains cables on to two terminals, and the sensor on to two terminals. And then you hook up your heating element to the SSR and mains (depending on how the SSR looks). Easy peasy.

  2. #32

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    The really critical step is the first developer (E6) or developer (C41 and RA4). You can usually manage to get the developer to some known high temperature before you use it, at least for a few minutes. The instructions for the original Mitchell Unidrum (same as Beseler, but a bit earlier) included a chart for the drift through method for processing prints. If you know the room temperature and the development time, you could look up a starting temperature for the developer that would produce good results as the developer cooled down and drifted through the target temperature while you developed at room temperature. You usually started at something like 104 (for 100 F processes) or 77 (for 75 F processes). The idea would probably still work for film and prints, but you might have to do some experimenting to determine the right starting temperature. The other solutions all work to completion and are less critical for temperature. Plus or minus 2C is usually OK. It is pretty easy to build a solution warmer to keep solutions at a elevated temperature. Start with a container that will hold the bottles with some room to spare (fish tank?) and use a fish tank heater with a built in thermostat to maintain the temperature. It works quite well.

  3. #33
    Diapositivo's Avatar
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    Stock fish tank heaters never arrive to 38 °C because fishes would not survive at that temperature. So if you use a fish tank heater you have to modify it (read: break the temperature limiter) so that it can reach 38 °C.
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  4. #34
    ChrisC's Avatar
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    Thankfully my gas hot water has a digital temperature regulator on it which is pretty stable, so I use that for the pre-soak (usually a 2 step bath, just to make sure), then I just heat up my chemicals in an old microwave until they're 1ºC or so warmer. While the developer's doing it's thing I get a stop bath running from the tap water while heating up the blix in the microwave, then it's all downhill from there.

    Eventually I'll make one of these http://www.youtube.com/watch?v=suQTE3wx_Jk with a water heater/thermostat inside it to make everything idiot-proof (which I could probably do with) and I'll be away laughing. I'll probably forgo the relay and just put in a manual reversing switch like I have in my current motorbase, though I've run it without reversing before and didn't notice any adverse effects.

  5. #35

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    How to guide on temperature controlled water bath

    Quote Originally Posted by olleorama View Post
    It's not really that hard. My pid-thermostat had screwconnectors for all cables. All you need is cable stripper pliers (or a knife/scissors) and a small screwdriver. But my thermostat is not chinese, so I don't know how to hook those up, some of them need an external relay, mine has an internal relay. I can take some pics in the morning if you like. The things you need aren't found in a home-improvement store though, I'm afraid. Well, maybe you can find a cooler that you can use.

    The ebaystore mixtea has sensors, SSRs and thermostats. The sensor is easy to hook-up, just remember to use shielded cable if you need to extend the cables. The thermostats he sells must be used with a relay, use a solid state one (SSR). There is a pdf on sestos site which tells you which terminals to use.

    Basically you screw or solder the SSR (solid state relay) on to two terminals, your mains cables on to two terminals, and the sensor on to two terminals. And then you hook up your heating element to the SSR and mains (depending on how the SSR looks). Easy peasy.
    I saw this post a while back and it stuck with me. Eventually I decided to try it out and I've found a lot of success with it. I put the water in the bucket, turn on the system and it regulates the temperature to whatever I set. I've developed many rolls of c-41 with this system, and it's always at 39C, no matter what.

    I've written up a tutorial on how to make your own system using the basics that olleorama laid out, with some additional information pulled from home-made sous-vide machines. Like he said, it's a pretty simple setup that won't cost too much to put together. In the end you'll have a highly reliable system that will make your life easier.

    Check out my site for the tutorial:
    http://www.fumblingwithfilm.com/how-...eveloping-c-41
    Last edited by fumblingwithfilm; 01-31-2012 at 03:48 PM. Click to view previous post history. Reason: added the link

  6. #36

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    Quote Originally Posted by fumblingwithfilm View Post
    I would post the link to my tutorial, but since I'm new I can't
    pm me the link and I'll post it.
    Steve.

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