Thursday, March 13, 2008

The Heated Mouse

Not only do I work in the basement of my building and not only are there lots of computers (and thus lots of AC) but one of the AC vents is right above my desk. Oh and of course I sit still all day. So I get cold hands. More specifically, I get a cold mouse hand.

The obvious1 solution to this problem is a heated mouse. Google can tell you this isn't a new idea but google can't tell you where to actually buy one. The only place that sold them is now dead and in any case seems to have been a scam. People didn't get their shipments or they did but the contents either failed to work as heaters or failed to work as mice.

But this can't be complicated. USB is a powered connection, meaning that a mouse can get power from the computer. If it can draw enough, it can run a tiny heater. As a matter of fact, the USB spec says that a device can draw up to 500mA at 5V, which is 2.5 watts. That's not a lot of heat, but if you were holding it literally in the palm of your hand I thought it might be enough to ward off pneumonia.

USB optical mouse and resistance wire from hair dryer.

Entire inside of optical mouse, USB cable unplugged from board. Red/black are power, don't mess with the other wires (data).

(I really should have photographed this entire build, but I was feeling my way through and didn't want to waste time with a bunch of dead ends.)

The first thing was to get a USB optical mouse. USB for the power, optical to have plenty of space inside. I had one lying around. Then I needed a way to turn electricity to heat. Resistance wire out of a trashed hair dryer turned out to be perfect. Around 3" of wire (coiled length), coated with liquid insulation, provides ~20 ohms of resistance. That draws about 250mA, providing around 125mW of heat. (I stayed well below the spec just in case, plus the mouse itself needs 100mA, according to the label.)

The rest was just a bunch of boring details. How to keep the heater wire inside the mouse. How to attach the power to the coil. How to get the mouse back together. Thinking about safety. Like, am I going to burn down the building? I don't think so...

Does it work? I've got it plugged in right now and it's working great. Works fine as a mouse (didn't even have to reboot, even though I switched from PS/2 to USB) and as a heater (I switched because my hand was cold and now I'm comfy).

I'd say the only problem is that the heat is applied more towards the palm when it needs to be more towards the fingers. It works as-is, but maybe I could uncoil the resistance wire and spread it out a little more around the inside of the mouse to hit all the areas.

1To a dork.


  1. I work right next to a large piece of medical equipment and the A/C setting in here is permanently set on Fricking Freezing.

    I'm toasting myself with a (contraband) space heater RIGHT NOW.

    I like this heated mouse idea, but that still leaves the other hand out in the cold. I'm about to start bringing a baked potato to work in my pocket ala Little House on the Prairie.

  2. I was trying to avoid a discussion of where my other hand was, but suffice it to say it usually isn't cold. The other solution of course is a heated keyboard, but the contact surface area and dwell time are too small and short respectively. Also, you'd have to heat all the keys. Or at least 9 of them.

    At a previous job I did have a regular (nontraband) space heater and while it warmed my body my mouse hand was still cold. I guess the extreme immobility, plus being so far from my body, plus having the wrist pressed against the cold desk does that. For a while I had the heater just pointed down at my hand to warm it up. So basically this is the same thing, but 1000x more efficient (1 kilowatt vs 1 watt).

    I forgot all about the baked potato in the pocket! I should get a mouse made of soapstone. Also, run a rope from my office to my car so I don't get lost in a blizzard.

  3. you can buy a heated mouse (and some other heated computer accessoires) at!

  4. Only $80 (+ shipping), that's quite a deal compared to

    And that's assuming this isn't the scam site everyone was warning of.

  5. Wow, I can't believe this worked. I'm extremely impressed.

  6. You didn't just make the mouse hot---ROWR. I love a man who can solve the cold-fingers problem.

  7. @tps12: Did I already tell you this plan?

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  11. Now there is no need to build your own warm mouse, you can get all sorts of warming computer gadgets at The have a heated mouse, a heated mouse pad and mouse blanket that you can put them all in. The heat is infrared heat which is a good form of healing heat. Try them I purchased the items and they work just great.
    The site says they will have a heated wrist pad shortly

  12. $80 + shipping is WAY too much money to pay for a warm mouse.

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