proximity TO EACH OTHER sensors?

Discussion in 'The Projects Forum' started by aliasjanedoe, Oct 28, 2013.

  1. aliasjanedoe

    Thread Starter New Member

    Oct 28, 2013
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    I've seen several tutorials for creating proximity sensors that will detect anything, but I want sensors that will detect only each other. Basically, I want to have LEDs inside tiny toys that will light when the toys are near each other, then fade and turn off as they are separated. Can anybody point me in the right direction? Thanks.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you have two sensors, one in each, why not also place a detector 'flag' or whatever type of sensors you are using?
    But they are normally ON/OFF types, not linear.
    Max.
     
  3. aliasjanedoe

    Thread Starter New Member

    Oct 28, 2013
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    Because I don't know what parts to buy that will do this. Can you please explain in more detail? If it just turns on/off without fading gradually, that's okay.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There are IR (Infra red) types or magnetic types that require a small button magnet on the opposite toy, the latter would be OK as long as the toys are not metallic, otherwise they would stay attracted on contact.
    Honeywell offer an assortment of both types.
    The magnetic type are the SS400 series. Bipolar, Unipolar or Latch.
    If you search places such as DigiKey for e.g. the IR
    http://www.digikey.ca/product-detail/en/SDP8611-003/480-5176-ND/2513195
    Max.
     
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  5. aliasjanedoe

    Thread Starter New Member

    Oct 28, 2013
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    Brilliant, Max, thanks! I'm definitely doing magnetic for just on/off.

    However, I'm still interested if anybody has ideas for the gradual fading that aren't too difficult.
     
  6. John P

    AAC Fanatic!

    Oct 14, 2008
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    I'd have thought you could put an infrared beacon on each toy (flashing at some rate would probably be best) and a matching detector. Though I can see complications coming in when you get a whole cluster of the toys--the beacons would interfere with each other, unless you figure out some way to have them recognize that they're in a crowd and limit the beacon operation. Also, must these sensors operate in any orientation?
     
  7. aliasjanedoe

    Thread Starter New Member

    Oct 28, 2013
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    Max's magnetic idea solved on/off for a single pair that touches in a specific orientation. But you're correct in that ideally they should grow brighter/dimmer with distance and in any orientation. Ability to find their partner (or multiple friends, but this adds a whole other level of difficulty) amongst a crowd would also be really nice, but a solution for a single pair would still be great.

    Maybe if the IR flashed at different rates (then reflective surfaces wouldn't cause them to set themselves off). But I'd need multiple IR and sensors in each if I want 360 orientation. This would probably be too complicated and expensive.

    I also thought about RFID, but I've never used it and really know nothing about it.
     
  8. MrChips

    Moderator

    Oct 2, 2009
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    I would try a simple IR emitter. The receiver would be an IR detector that controls the current through a visible LED in order to give varying brightness.

    I will provide a circuit after I get a chance to test it.
     
  9. John P

    AAC Fanatic!

    Oct 14, 2008
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    If you don't modulate the IR light, receiving it will be pretty much impossible if there's any daylight or incandescent light around.

    When I said "any orientation" I was thinking 3 dimensions. Not with the idea that the toys could fly (though they might!) but perhaps people would hold them in their hands and expect them to detect each other no matter which way up they were held. If they actually travel on a flat surface, it's a lot easier.

    Another idea might be sound--maybe audible to humans, or not. The louder the buzz, the brighter the light. Would it be a good feature that many toys would be louder than just one, so detection would happen from longer range?
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    Try this:

    [​IMG]
     
  11. sirch2

    Well-Known Member

    Jan 21, 2013
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    As John P indicated, is that circuit not just going to be overwhelmed by IR from daylight or incandescent room lighting? That is what I found when messing around with a similar setup.
     
  12. aliasjanedoe

    Thread Starter New Member

    Oct 28, 2013
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    I think a sound that's not audible to humans would be best. Buzzing might be fun for a little while, but would probably start to get annoying rather quickly.

    And, John P, you're right, people are probably going to pick them up. I hadn't really thought of that, but it's a very good point.

    Another thing to consider is distance. I was thinking a few inches, but a long range sensor that would work across a room would be really fun also.
     
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