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Invention in need of professional help.

  1. Jul 23, 2012 #1
    I have an idea for an invention and I am trying to work out the circuitry. I need some type of rotary switch or another devise that will be user adjustable and assigned to a given weight, then when that weight is achieved on a scale it turns on a basic LED light. I know its a really loaded question but any advise in basic terms would be much appreciated.

    Thanks in advance!
     
  2. jcsd
  3. Jul 23, 2012 #2

    vk6kro

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    If you wanted to do it with a mechanical device, probably a variation on a spring balance would be used.

    The weight stretches a spring and this could then make a contact with a switch.

    Varying the position of the switch would vary the weight needed to cause switching.

    Cheaper bathroom scales still use this system but newer, more expensive ones use load cells.
     
  4. Jul 24, 2012 #3
    That's great vk, I appreciate the response. I have sat for the last couple hours with a spring scale and have a pretty decent understanding of the mechanics. I am still struggling with what you mean by Varying the position of the switch would vary the weight needed to cause switching. What does that look like? What kind of rotary switch could I use? What would the mechanics look like on the inside?

    Thanks to everyone for their help.
     
  5. Jul 24, 2012 #4

    vk6kro

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    If you have a pulley which rotates when pulled by a rope, but is spring loaded to return to its original position, you could mount a piece of metal on the rim of the pulley which will operate a switch when the pulley rotates far enough.

    So, a sufficient force on the rope will cause the switch to be operated and turn on a light.

    You could have the switch on a platform which could be rotated so that different positions of the pulley will operate the switch.

    As part of your invention, you would have to adapt this principle to suit the design.
     
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