Ideas for Noob on making Automated washer (timer circuits and valve regulation)

Discussion in 'The Projects Forum' started by icehole, Oct 6, 2012.

  1. icehole

    Thread Starter New Member

    Oct 6, 2012
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    Hi,

    I am a noob to the forum and somewhat electronics in general. I can solder components together and reasonably figure things out. I am wanting to create something that I can use in my lab to expedite my projects. I will explain what I am wanting to do and I hope someone would have advice on how to get started.

    In a broad description: I wash tissue in a small petri dish with a saline solution 6 times for 10mins a cycle. By hand I place liquid into the petri dish, about 2-3 ml, suck it out and replace. I would like to build a rig that would do this for me.

    What I have thought is that I need a power controlled regulator that will dispense liquid (i am thinking like a stop-cock that would be motored). Gravity will be used to dispense the liquid and thus valve would just impede the flow. This would need to be open for variable amount of time (i guess some sort of pot or trim pot could be used to adjust for amount of volume). So I could flip on a button and this valve would open for a few seconds then close for 10mins before opening again. It would repeat this cycle until I turn it off.

    I plan to place a hole in the bottom of the petri dish and thus liquid can flow out, this will also use gravity to evaucate the contents, but will need a valve at the bottom. Essentially this would be same circuit as above but offset in time so that the tissue in the perti dish would not ever become completely dry.

    I presume that this would require use of two timers, some motorized valve for the most basic set-up. I am not experienced enough to even know where to start other than conceptually visualizing how this would work.

    Any help on this would be greatly appreciated.

    Thanks,
    Chris
     
  2. icehole

    Thread Starter New Member

    Oct 6, 2012
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    bump......
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    745
    Here is a 10 sec on 10mins off timer, that pules a relay, which you can feed your valve or 12v car washer pump, the delays are variable to suit
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    I assume the saline wash is sterile?

    A peristaltic pump would be an option, since it acts as a valve as well; no turning means no flow. I've used one in a lab that had a programmable on and off time, and could deliver a calibrated "shot" on each cycle. We used it for filling plates and culture tubes - repetitive stuff. I don't think we ever used it in reverse, but it probably had that capability.
     
  5. icehole

    Thread Starter New Member

    Oct 6, 2012
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    Thanks for the information. The two resistors at URC are these what control the delay? If so could i use a trim pot or equivalent in place of those?
     
  6. icehole

    Thread Starter New Member

    Oct 6, 2012
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    Thanks for your response. This is fixed tissue that I am using and washing for immunohistochemistry and are just using 0.1M PBS, so pretty much saline. Sterility not much of a concern, but mixing outflow with inflow might be problematic.

    We have extra peristaltic pump lying around and most do work in reverse. Thanks for the suggestion, I will tinker with it and see what I can get to work. My hope is to at some point be able to wash multiple culture plates at one time, 2-4.
     
  7. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745

    Yes , they are trim pots I call them variable resistors or presets, one is 220K, the other 10Meg, the 220k will give you a delay of upto 22 seconds, the 10Meg will give a delay of upto 17 mins, the relay is to suit your self, any 12volt coil with a set of change over contacts will do.
     
    Last edited: Oct 13, 2012
  8. icehole

    Thread Starter New Member

    Oct 6, 2012
    5
    0
    Getting ready to put together this circuit. Had another question. On the IRF830 component it appears that all three pins go to ground, is this correct or am I missing something?

    Thanks.
     
  9. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    wrong, it has 3pins, the Source goes to gound, the Drain to the relay,the Gate is the input.
     
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