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Simple touch switch needed

  1. Aug 27, 2007 #1
    I am looking for a very simple touch switch/sensor that I will be using to activate a small servo. The sensor will be connected to a microcontroller to accomplish some very basic processing of any input received. I've been told that a capacitance switch would do the job, but I've been unable to locate one that I could easily incorporate into my project. If a capacitance switch is not an easy solution, please suggest an easier alternative.
     
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  3. Aug 27, 2007 #2

    berkeman

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    Staff: Mentor

    I like to use individual switches of the PC keyboard style. They are nice for test fixtures, etc., because they have a nice feel to them, and have very long life compared to regular pushbuttons. Like the Cherry MX Key Switch series....here are some links:

    Datasheet -- http://www.cherrycorp.com/english/switches/key/pdf/keyswitch_cat.pdf

    Digikey catalog page (see bottom of page) -- http://dkc3.digikey.com/PDF/T072/P1756.pdf

    You can order one of hte styles that you like (tactile or not, mounting options, etc.), and also order the Keycap. I like the tactile click version myself.
     
  4. Aug 27, 2007 #3

    dlgoff

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    I made a set of touch sensivite switches that uses a 5MHz oscilator using 3 nand gates of a 4011 chip and coupling ( with a ?pf cap by twisting about a 1/4 inch of 30 gauge wire together) it to the base on an NPN transistor. The base of the transistor also had a 100 Kohm resistor to ground and a small copper touch plate. When you touch the plate, the transistor becomes unsaturated. giving a high on the collector.

    I worked very well. You can tune the sensivity by the number of twist on your ?pf cap.
     
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