Build a simple switch

Forget hacking an easy button, grab a couple of those outdated CD-Rs and build your own switch for that next project. This was developed with handicapped accessibility in mind; assembled easily with common products and it’s fairly robust. In fact, our junk box has everything you need except the adhesive backed copper foil. Combine two old CD’s, covered in copper on facing sides, separated by two strips of Velcro to separate the conductors. When pressure is applied, one CD flexes to make contact with the other and complete the circuit. So easy, yet we never thought of it. We’ll add it to our list of homebrew input devices.

[Thanks Michael]

Comments

  1. NickS says:

    This idea has been around forever. The Army’s Improvised Munitions Handbook has something similar as a trigger for IEDs.

  2. Erik Johnson says:

    At first glance the picture made me think it was a capacitive sensor like the puck some add-on touch lamp switches use

    It’s basically a membrane switch/button, just like most keyboards use (flex conductor, spacer, flex conductor)

  3. Birdy says:

    I’ve done something similar to this with 2 pennies, a small piece of sponge, electrical tape, and speaker wire….great if you place it under rug and use it with batteries and a light as a simple alarm if someone is approaching your door

  4. cgmark says:

    As suggested you can also use a CD, not CDR for capacitive input sensors. Cut into the foil in the center and attach your sense lead. These should be able to work with the ST8 boards that have capacitive features built in.

  5. Dave says:

    I hope this is to be used for low voltage applications

  6. RM says:

    Great use for an old Windows 2000 CD as well.

  7. Ryan says:

    I would class the concept as general knowledge.
    Used a lot in children toy manufacturing to reduce costs.
    Would be more ghetto if aluminion foil was used.

  8. Jim K. says:

    Instead of copper foil, why not use aluminum foil as per the following?

    http://softlyspokenmagicspells.com/halloween/mat_switch.html

    Not thumbing my nose at this solution, just thinking about what I more often have on hand around the house.

  9. chiefcrash says:

    Old but good idea. I used to make a switch like this with just 2 stiff pieces of cardboard, some aluminum foil, and drinking straws. When I was a kid, I used to put one under the carpet in front of my room’s door so I could tell if someone was standing outside…

  10. RussWill says:

    Why is this here? There are a million better ways, and better reasons…

  11. jamieriddles says:

    Cool, makes me wish I collected all those damn AOL discs

  12. Dave says:

    Let’s not be critical of the technical idea as we all see it clearly exists in other forms but moreso the hack itself of being able to use 2 CDs as a switch.

  13. jeditalian says:

    the 5-inch ass-cheek sensitive switch. because paper clips, clothespins, aluminum foil, safety pins, thumbtacks, nails, screws, strips of sheet metal, and plain ol’ wires just don’t cut it.
    i have a fun idea: throw it in the microwave. everybody’s done it with one cd, some have done it with an entire stack, but the whole parallel plate(cd) capacitor thing.. haven’t seen that one yet.

  14. kyle says:
  15. amk says:

    For a larger switch two sheets of window screen separated weather stripping in a grid like pattern works great, and fits nicely under carpet.

  16. Gavin says:

    Oh hey, that’s me! Cool!

    Thanks for the comments, criticism, and related ideas, guys.

    Just to be clear, I didn’t make that guide because it’s a new or particularly complex concept. It’s just that many of the teachers, therapists, parents, etc. who work with people who have disabilities don’t have a lot of experience with circuits and such. I wanted to show them how simple it is to make their own inexpensive tools, and give them a clear guide to do so.

  17. Whatnot says:

    Copper foil is a bit elusive in my area, but aluminium foil and tape is readily available though.
    I’m just saying that you should not assume too much of what’s in people’s junk drawer mike.

    Coincidentally I am in some need for some copper foil to close a gap between 2 surfaces that need thermal contact but with a gap that’s too wide for thermal paste, so I’m a bit peeved that I’d have to get it online it seems and pay shipping.
    So if anybody knows where I can retrieve a bit from? The only source I could think of so far is high quality coax cable, but that’s too thin (and costly).

  18. I like it!
    FYI – Foil tape, hardware store, for ducking etc…

  19. Ryan Leach says:

    This is great!
    Reckon I’ll use it for a DIY home DDR pad.

  20. strider_mt2k says:

    Wow.

    At least the last switch involved a couple of Hot Wheels cars to keep it interesting…

  21. Drake says:

    Bag clips + aluminium foil make momentary naturally closed and naturally open switches.

  22. fartface says:

    This has been around for over a century. Just because you use a “cd” does not make it innovative.

    Wood, ducks, small churches all have been used for this as long as electricity has been around.

  23. dan fruzzetti says:

    why not just use cheapo un-coated, un-printed cds turned back-to-back for the same effect? would this not work?

    @fartface: you forgot very small rocks

  24. ieds|suck says:

    great. more cheap pressure plate ideas.

  25. spadefinger says:

    Heh. My first thought was that it was going to be an ethernet switch when I clicked the link. That would have been interesting.

    On the IED angle and the W2K CD, I guess it might give a new meaning to BSOD.

  26. walt says:

    instructables BOOOO!!!!

  27. Protowizard says:

    good way to use dell OEM Disks LOL

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