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Homework Help: Shock detection switches

  1. Mar 4, 2010 #1
    As part of an engineering design project, I am using shock switches to measure accelerations of an object. As the name suggests they are just switches that turn on when a shock above a certain value is experienced.

    Does anyone know the details about how the switch contact is closed when it experiences a high enough shock in the following shock switch ?http://uk.farnell.com/assemtech/asls15/switch-acceleration-15g/dp/4229071?Ntt=422-9071"

    I can't find any information on the internal structure of this shock switch anywhere on the net.

    One of the conducting legs is attached to the outer gold plated housing and the other goes right through into the middle of the device, insulated from the housing. When you shake the device hard enough (over its shock threshold), you can hear a rattle, as if there is some sort of ball in there. I was thinking that there might be a ball contained inside a conductive cylinder connected to the middle leg that rises and touches the top of the housing, which is connected to the other leg, hence completing the circuit between the two legs. But why would the ball only move up and down the cylinder when a high enough acceleration is applied? Surely if it is just a friction fit cylinder, then the ball would get stuck at the top and the switch would be permanently closed?

    I really need to know the mechanics behind this device to write about in my design report.

    Any help would be greatly appreciated.

    Many thanks

    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Mar 4, 2010 #2


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    Staff: Mentor

    Looks pretty inexpensive. Can you just cut one open?

    I found a couple things with Google Images, but no great hits with a quick search. You could try browsing at wikipatents.com some -- it's probably patented:

    http://www.wikipatents.com/simple_text_search [Broken]

    Last edited by a moderator: May 4, 2017
  4. Mar 4, 2010 #3
    Thanks for reply.

    I could attempt to cut one open but I would prefer not to since I only have a week left to write the report and may need to test all of them. I can't find any patent filed by Assemtech or a patent on any similar device.

    I have found something that suggests it could be a ball on a spring. Presumably it works via base excitation but I am unsure.
    Last edited: Mar 4, 2010
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