solenoid push button

Discussion in 'General Electronics Chat' started by praondevou, Nov 14, 2011.

  1. praondevou

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    I'm looking for a push button with an integrated coil. Pushing the button would move a magnet inside the coil and therefore create a voltage.

    I'm sure it exists somewhere because wireless light switches exist that don't require batteries nor wire connection. I'm just not sure if they are commercially available as single units.
    I could build one with a small relay coil or similar, but it's kind of unprofessional. Has anyone seen something like this?
     
  2. mcgyvr

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    Where? Anyone I've seen required batteries or was hooked to the house wiring.
    The amount of energy from just pushing a single push button is very..very..very small.
     
  3. praondevou

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    http://www.adhocelectronics.com/Products/Wireless-Lighting-Control

    Look under "How it works". I want something similar but smaller, as small as possible. I need only about 6mA for 10ms at 3.6V.
    I did some tests with a vibration motor from an old cellphone but I get only about 100mV for a 2 to 3ms. I could pass it through a boost converter (energy harvester for example) and charge a capacitor. But I would like to activate my circuit with a single button press.
     
  4. SgtWookie

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    I'm thinking that they could be using a piezo element instead of magnetic.

    Piezo elements can be quite small, and just need a sharp impact to generate electricity for a moment.
    http://en.wikipedia.org/wiki/Piezoelectricity
    For example, take a look inside one of those butane lighters used for starting BBQ's.
     
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  5. Feign

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    The mechanics for what you want can be found in a BBQ lighter, or any with a spark starter. But then your light switch turns out with a bit of a Harry potter feel, due to the layout of the device. If you can fabricate a rocker switch to opperate two of them it would be more 50's TV clicker.

    I assume the commercial remotes use a jewel thief, and button cell
     
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  6. Feign

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  7. thatoneguy

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    Closest Patent I could find Uses a piezo element to power the RF momentarily, but this is for automotive applications.

    I could see it being modified for home use if the receiver has enough sensitivity.
     
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  8. mcgyvr

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  9. praondevou

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    LOL, I liked that. :rolleyes:

    Thanks to all, I read about the Piezos before but from what I understood they put out peak power at their resonance frequency.... Not sure how I could get there with a single button press. Will do some more research in this direction.
     
    Last edited: Nov 15, 2011
  10. SgtWookie

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    If you plucked a piezo like a string, it would resonate at its' natural frequency.
     
  11. praondevou

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    The piezo I found that is affordable puts out 3.4nC at 2mm deflection. I need more like 20uC to power a transmitter for 10ms.:(
    I will buy one anyways to do some testing.
     
  12. colinb

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    It looks to me like that switch has a large coil that must be involved in generating power. “Micro Generator”, they say.

    [​IMG]
     
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  13. SgtWookie

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    Yep, certainly is...
    wow, there sure are a lot of parts on the board. Good candidate for a VLSI.
     
  14. thatoneguy

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    The inductor and room needed for the SAW to build and transmit through antenna wouldn't reduce it much below the size of the transformer, though. I think it would surely fall into the category of "nanopower", through. Assuming it uses one inductive spike to charge the cap and spit out it's ID code just as quick with an of or on, then be out of power until it is pressed again.
     
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