Need direction to control small 12v motor run time while using momentary toggle switch to activate

Discussion in 'The Projects Forum' started by mmorgan, Apr 12, 2016.

  1. mmorgan

    Thread Starter New Member

    Apr 12, 2016
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    I am controlling a 12v system that drives a cam which rotates under a hopper to deliver a "dose" of product. This project is to deliver a product for biological control of mosquitoes in catch basins in mostly urban areas.
    As it is set up now, I hold the momentary toggle switch to activate the cam and release it after a single revolution. Ideally, I would like to merely activate the switch and have the cam turn a single revolution and stop on it's own, awaiting the next activation.
    Any guidance would be much appreciated. The photo is of the cam at the bottom of the hopper to give you an idea of the space I have to work with.
    Thanks.
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    You just need a latching relay circuit. "Start" would be your pushbutton and "stop" is a limit switch positioned to operate when the cam is at its home position.
    [​IMG]
     
    Last edited: Apr 12, 2016
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  3. mmorgan

    Thread Starter New Member

    Apr 12, 2016
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    blocco a spirale, thank you for the fast reply to my thread. I also appreciate the diagram very much, it helps out a lot! Being a novice (which is probably giving myself more credit than is due), can you advise on the best avenue available for an appropriate limit switch? Would online be the best bet or maybe Radio Shack? Thanks.
     
  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Look out for a microswitch with a long lever and maybe a roller (it depends on how you intend to install it), something like this:
    [​IMG]

    I'd first check ebay for this kind of thing but any of the online component suppliers will have something suitable.
     
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  5. mmorgan

    Thread Starter New Member

    Apr 12, 2016
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    Excellent, thanks again!
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It might be wise to keep the stop switch and wire the micro-sw in series with it, this will then give you both manual and auto stop if you needed it.
    Max.
     
  7. mmorgan

    Thread Starter New Member

    Apr 12, 2016
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    Good idea, thanks.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Also depending on fast the hopper starts, you will need to hold the start in for enough time for the hopper to rotate off the limit, otherwise it will give a momentary pulse.
    Max.
     
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