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
- batteries
- 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)).
10 Comments
- brent replied:
excellent nerdiness, as usual. great work.
August 29th, 2007 at 1:27 am. Permalink.
- Ryan replied:
Interesting, thanks.
October 1st, 2007 at 12:29 pm. Permalink.
- ross replied:
Do you have any more pictures/ diagrams of the toothbrush i can use for my report?
November 6th, 2007 at 1:30 pm. Permalink.
- Anita replied:
Ross, I don’t have much more to offer, sadly — The other photos I have are just blurry versions of the ones you see here. I can give you higher resolution versions if you like; just email me.
November 6th, 2007 at 1:42 pm. Permalink.
- Lisa replied:
Hiya
we are doing a school project on the electric toothbrush and i have to make a circuit which will improve my current Braun vitality brush. i was wondering whether when you took your toothbrush apart there was much room for maybe a second similar sized circuit board and if not how much room will i need??
thanksMarch 10th, 2008 at 9:25 am. Permalink.
- Anita replied:
Nah, there isn’t a lot of extra room in there. You might be able to fit a circuit board about 0.75 inches x 0.5 inches in between the batteries and original board (which is best viewed in this picture). Still, your brush may be different. And I’m still curious how you’re going to put it all back together, since I pretty much had to destroy it to get it open.
I’d love to see you post a comment here when you’re done, so we can see what you did! :)
March 10th, 2008 at 8:40 pm. Permalink.
- purposeinc replied:
Thanks for the insight. You saved me searching any more for sonicare fixes, and instead I will put it aside in my toxic, not for regular garbage or donation pile.
February 9th, 2009 at 4:33 am. Permalink.
- Jim Holmes replied:
Hi, I open my Sonicare and cannot find any soldering wires. The PCB is soldered to both input power coil and tooth electro-magnet coil using pinned terminals. I am unable to remove/replace the two AA Cad batteries. Any comments on how to remove the PCB? Thank you.
June 3rd, 2009 at 2:05 pm. Permalink.
- Jim Holmes replied:
I am unable to close and seal it back without leaking water inside. How did you do yours?
June 9th, 2009 at 10:23 am. Permalink.
- Anita replied:
Jim: If I remember correctly, I snipped the wires to the PCB, and it just came right out. Then I popped the batteries out pushing the tip of the screwdriver underneath them and pushing on it like a lever. I never put the toothbrush back together (I threw it away). Since I cracked the case open, I’m imagining that would be very difficult to do without leaking water inside.
June 9th, 2009 at 10:43 am. Permalink.
