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Is there a name or a part-number for the type of kill switch used on a model rocket launcher ? The switch is closed by putting the key (basically a metal pin) into the hole.

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Is there a module I could buy, or if not does anyone have suggestions on how to build one?

This would be for low voltage application.

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    \$\begingroup\$ It's just a couple of pieces of sheet metal bent so that they don't quite touch, and the pin pushes between them to complete the circuit. The sheet metal pieces are probably very simple but custom designed to mount to some features inside the plastic housing. \$\endgroup\$ – The Photon Aug 7 '15 at 18:16
  • \$\begingroup\$ That sounds about right. My only concern is what would keep the bend in sheet metal from warping too much so that the pin no longer completes the circuit. \$\endgroup\$ – Walter Stabosz Aug 7 '15 at 18:44
  • \$\begingroup\$ 1. The makers of that product probably don't care too much about reliability, so they get away with it. 2. They probably use spring steel (or the cheapest alternative) which might be a crappy electrical conductor but good enough to deliver the needed pulse to the igniter. \$\endgroup\$ – The Photon Aug 7 '15 at 18:55
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One of the most common switches of this type is made from a 3.5mm or 2.5mm Tip-Sleeve or Tip-Ring-Sleeve jack commonly used for headphones.

The better designs actually use a proper plug to go into the jack, with the pins soldered together inside the plug. The advantage of using a proper plug is that the jack grips the plug firmly.

Less expensive designs use a metal rod of the proper diameter with the end rounded or tapered to as to enter the jack easily. However, the rod pulls out of the jack easily.

This is an inexpensive and relatively-robust method.

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I think the term you're looking for is "key switch" and there are all types available from a variety of suppliers online. Most are more sophisticated than simply inserting a short metal rod between two metal contacts.

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