Mouse Modding :-)

Blue LED for optical wheel mice.

The first and easy mouse

The first mouse I modified was a Genius Net Scroll. This mouse is smaller than normal mice and has a very smooth wheel. I like it very much and use it for my laptop.
The LED was replaced easily and the modified mouse worked very well. There’s nothing more to say about it.

The second and more complicated mouse

Now I took my Logitech optical wheel mouse. This one is normal sized and works well with my desktop machine.

I replaced the LED which was as easy as before. Also it really looked very nice as you can see in the following pictures.

But after some time I realized that the wheel was not working well anymore. First I thought it was a mechanical problem, but as you will see it was not.

I opened the mouse again (probably for the 10th time) and took my multimeter. I remembered that I bought a very strong blue LED (of course ;-) and so I guessed that mybe it’s using too much current so that there’s not enough current left for the LED used to track the wheel. So I measured the voltage drop over that LED (LD2 in the picture below) which was 0.181 V. I decided that this was to low and simply bypassed the multiplier (R2 in the picture below). This increased the voltage drop over LD2 to about 0.25 V.

Believe it or not, but the wheel worked perfectly again. ;-)