Inside my Sonicare toothbrush
Last week I took apart my old and recently-broken Sonicare toothbrush, to remove the batteries before throwing the rest away. I thought the insides were interesting, and that others might like to see.
I pried open the case with two flathead screwdrivers; it cracked cleanly down the sides. Then I snipped the wires connecting the circuit board, and popped out the batteries (which turned out to be really normal “AA” NiCad rechargeables, except that they had leads soldered directly to the contacts — This was actually quite a disappointment, since, with such standard batteries, they should be easily replaceable… but to get at them you have to tear the whole toothbrush apart, breaking the housing, and destroying the whole thing).
The inside contains:
- circuit board
- two coils of wire, one on the bottom (next to where it would sit in the charger), and the other at the top (next to where the brush head attaches)
- a magnet at the base
… seems like the base is magnetically coupled to the charger, so that the current is passed from the charger to the coil in the toothbrush base via a magnetic field. This inductive coupling is not terribly efficient, but allows you to have a toothbrush that is completely sealed/waterproof, and that at least gives the perception of being safer due to a lack of metal contacts ((Draft Battery Charger Energy Star Standard)).