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Thread: motion sensor shut-off

  1. #1

    Default motion sensor shut-off

    Hello.
    I have a solar powered pump (24v). When the pump is left on on cloudy days (low power)it is hard on the electronics. The pump appears to draw between 4 and 17 volts to work depending on cloud. I want the pump to shut off at low power and thought I could use a motion light sensor (from a cheap security light.)to do the job. They normally run on 230vac from the mains and then convert to 24vdc. does anybody know how I could rewire it . From what I understand the sensor itself only needs about 5vdc. Could that be worked off the flow switch wire that is present. Any ideas in plain language would be welcome.

  2. #2
    Rancher
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    Do you have batteries in this setup, or are you powering the pump directly from the panels?

    Rancher

  3. #3
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    I haven't yet grasped the idea of what a motion sensor is going to do to stop a pump from running, solor or otherwise.

    I believe a domestic motion sensor would plug into 115 volts not 230.

    bob...

  4. #4
    Rancher
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    Bob, I believe he wanted to use the photo eye function of the motion senser to turn the pump off/on.

    Here's what you need to buy, the set the adjustment to whatever you need to:

    http://www.ssac.com/catalog/CM-ESS.pdf

    The only problem is that it requires 24/48/120/240 VAC so... you would need a cheap inverter and of course a power source such as your batterys if you have them.

    Rancher

  5. #5
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    What motion is it going to sense John? That's what has me confused. I can see what your device does, similar to a Pumptec, right?

    bob...

  6. #6
    Rancher
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    Similar yes but I think the pumptec watches current, and this one watches voltage. It's probably must used to turn off equipment (A/C etc) during brown out conditions.

    I'm guessing that gradog is not from the USA... "230vac from the mains"

    Since our motion detectors typically operate from the 120 vac circuit. And we don't call them "mains"...

    Rancher

  7. #7

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    Rancher: The system works off two 44v panels direct to the 24v motor after being converted.
    Speedbump: I thought either the photo eye or even the motion sensor pointed at the belt and pully might work. In NZ the mains power is 230-240. I looked at the ac dc volt monitor. Would that switch off and on.? I'm no electrition. I did think of an inverter, but the cost was to much for what I was trying to achieve. I just thought you may have played around with a cheap security light and new how they could be rewired for a purpose such as mine.
    Cheers Gradog.

  8. #8
    DIY Member atfdmike's Avatar
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    Default Photo cell

    Back in the day you could build your own photocell setup pretty cheap and power it from a Commodore 64 or Atari computer. If my memory serves, the Commodore had a 5 volt output pin so the photocell was served by that. I just don't think it would handle the load you are looking at, but maybe the principle would be the same as far as power to the cell, you would have to hook it to a relay that was also powered by your available voltage? One guys thoughts.

  9. #9
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    Hadn't thought of that Rancher. Now I understand.

    As for the belt thing, I hadn't thought of the pump being turned by means of a belt. I guess if it would pick up on the movement of the belt, you could use it as a trigger to operate either a normally open or closed contactor to make the idea work.

    bob...

  10. #10

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    ATFD Mike.
    You are close to my thoughts. If the photo cell is run by 5vdc would it maybe run off the "flow switch" wire. At present that runs a pressure switch to turn off the pump when the tank is full. The flow switch is low voltage but I havn't quite worked out exactly what voltage or current runs through it. If that would work it would be easy to wire up. (I am from NewZealand. We run of mains 230-240 vac)
    Cheers: Gradog

  11. #11
    vaplumber
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    Maybe use a safety relay from the power window of a late model car with automatic windows. They run directly on 12 volt, so you would need to drop the supply to the relay with a resistor. When the motor stops moving it switches off the power, then you would simple shut the switch off and back on again to restart the motor. Also you can buy the relay at a parts house for about $25 U.S. dollars

  12. #12

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    Thanks for your contributions. I'll give it all some thought.
    cheers: Gradog

  13. #13
    Rancher
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    Quote Originally Posted by gradog
    The system works off two 44v panels direct to the 24v motor after being converted.
    Converted to what?

    You can probably use a CdS cell in some manner to do what you want, the off the shelf type stuff won't fit with the 24 v system you have. I thought maybe the light sensor in a typical US type outdoor light might do the trick however not sure how it will work at 24v, it should work with either AC or DC so you may give it a try. They make replacement moduals for about $10, it works by running a current thru the CdS cell and then a resistor on a bi-metalic piece of metal, the metal gets hot during the day becasue the CdS cell is basically 0 ohms in direct sunlight, when it gets dark it goes up in resistance, the bi-metalic switch closes contacts and the light comes on.

    Or... you might ask the hobbiest, they like challenges, go to http://www.nutsvolts.com/ they answer all kinds of wierd stuff.

    Rancher

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