This is an extremely simple mod and anybody who past arts and crafts in grade school could do this.
You take a cheap ~5$ electric toothbrush, like this one:
Inside the bottom cap (the part where you insert the batteries), you can see that only two batteries can fit inside to power the toothbrush, hence why it's so weak.
The mod is as follows:
Tape two more batteries to the bottom and enjoy spending 5$ on a 100$ toothbrush.
Let me explain:
The two batteries you insert by default go in like:
Now tape two batteries to the bottom, matching the leads like:
Use scotch tape or something thin for the batteries.
After they are taped in a 2x2 battery pack, insert them in the toothbrush like normal, the two extra batteries should be sticking out.
If you don't care about cosmetics, what I did was use packing tape to attached the case bottom to the two extra batteries hanging out (matching leads) and then wrapped the whole battery pack in a bunch of packing tape, as to seal the batteries and inside of the toothbrush away from water.
There you go, that's it. You should see an exponential increase in your toothbrush's head speed, making it on track with the expensive 100$ ones.
I'll post a video of the differences in speed as soon as I make one.
(I left my toothbrush at my girlfriends house... The video will be delayed. My apologies everyone :-/)
And remember to brush your teeth twice a day.
Update:
October 7th, 2010
Girlfriend's dog chewed the shit out of toothbrush. Will purchase another today and upload the video a.s.a.p.
Sorry for the inconvenience.
