A battery interrupter is a tool that adds a switch jack to (aka "switch adapts") an electrical device.

This is usually done for the purpose of allowing a person with disabilities to use that device, by using an "ability switch," which can be anything from a plastic button to a muscle twitch sensor.  These switches are almost always wired to a 3.5mm (1/8") mono plug, and can be connected to anything with a matching jack.  They are used with power wheelchairs, computers, speech devices, toys, remote controls, and so on.

A battery interrupter allows us to add a switch jack to a device that:
1) Is powered by AA, AAA, C, or D batteries.
2) Simply turns on or off with a single switch (like the infamous cymbal-crashing monkey).

A battery interrupter is simply a 3.5mm jack, with each of the two wires connected to small metal plates, which are separated by an insulator (like tape or thick paper).  These plates are placed between the batteries of a device, effectively redirecting the electrical circuit through the 3.5mm jack, so that it can be opened and closed with a switch.

AbleNet sells battery interrupters for $13 (USD) each here (and the manual is here).  You can also make your own battery interrupters by soldering a pair of wires (or a speaker wire) to a 3.5mm jack and to two small metal plates separated by double-sided tape or some other thin insulator.  However, if you are not comfortable soldering, this guide will teach you how to make a battery interrupter with only a few dollars worth of parts (or the scraps left from making a CD Switch).

Step 1: Materials

Materials needed:

- Adhesive backed copper foil sheet.  Two 1"x1" pieces. 
(Possibly the scraps from making a CD Switch. The kind with a black backing makes this easier.)
- Business card or small piece of poster board.  One 1"x1" piece.
- 3.5mm mono cable with female jack.
(Buy a 3.5mm mono extension cable, cut it in half, and use the female end for this, and the male end to make a CD Switch.)


- Scissors

Which nerf gun is that? Jacob will love it. He had a green Tommy gun knock off nerf gun, but it broke and he needs a good replacement.<br><br>Great job on making the interuptor. I needed one for a bubble machine he got for Christmas. Cheers! john.
It is the &quot;Nerf N-Strike Vulcan EBF-25&quot;, available here: <a>http://www.amazon.com/Nerf-N-Strike-Vulcan-EBF-25-Blaster/dp/B0013U95U2/ref=sr_1_2?ie=UTF8&amp;qid=1294385977&amp;sr=8-2</a><br> <br> The plastic tripod that comes with it doesn't really hold it in position well. I have much better luck mounting it to a table or wheelchair with a &quot;Manfrotto Magic Arm&quot; (aka Universal Mount) with a clamp on each end.<br> <br> There is more info on setting up and mounting these on my &quot;Combat Wheelchair&quot; project page here: <a href="http://www.gavinphilips.com/projects/combatwheelchair-1">http://www.gavinphilips.com/projects/combatwheelchair-1</a>
I have been thinking about this Light Strike guns :http://tinyurl.com/86k3puk<br>The battery interrupt should work to fire. Maybe a couple of servos to aim. One for up\down, the other for left\right, wired to your chair's joysitck or an Arcade joystick.
your Combat wheelchair is insanely awesome! I have made my son Jacob a Batmobile, a Land Speeder, and wanted a combat water gun. Your chair goes so far beyond, lol. Nice!
Can you use a stereo jack instead of a mono jack?
I suppose you could, and it might work alright. &quot;Ability switches&quot; in general use a mono plug, and I have had a few issues when connecting stereo to mono. Sometimes it seems like the contacts don't quite line up, and you have to pull the plug out slightly to make it work well. It's definitely worth trying, though, especially if stereo is all you have on hand.<br><br>If you try it, please let us know how it goes.
Nice, I use this kind of thing for clocks a lot to measure longterm signals in experiments.
Cool, I hadn't thought of that sort of application.
Nice project, you should swap around the pictures in your first step, so that is shows your finished version as the thumbnail, opposed to the commercially available one.
Done. Thanks for the input!
Thanks for sharing a nice easy, but useful project!

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