EEVblog > EEVblog Specific
EEVblog #284 - Braun Toothbrush Teardown
stryker:
Thanks so much for doing this Dave. I've wondered for a long time what was inside my toothbrush!
A question on the inductive charge coils tho. At one time you had the CRO hooked up to both coils, and the waveforms were a mirror of each other. How is it that the induction effects don't cancel each other out?
Cheers ! Geoff
madworm:
Nice!
Here's some more data ;-) I've got the same charger, only my "pickup coil" was inversed.
TbayBoy:
Exactly what I have been wondering about, inductive charging.. thanks (I'm still searching out research material)
NiHaoMike:
I believe the nearly flat bottom is from a transistor turning on. I have taken apart a similar toothbrush and it basically used a self oscillating converter.
I also suspect the motor was also operating as a boost converter, since 1.5V is not enough to effectively switch a typical MOSFET. High quality pictures would help.
IanB:
I haven't watched the video yet, but I HATE electric toothbrush designs (really hate). The reason? Somehow they don't seal them properly and moisture (condensation) gets inside and stops the electronics working. I mean, they know that electric toothbrushes are going to be subjected to immersion and steam, so why don't they make absolutely sure the enclosure is hermetically sealed?
Alright, I have to admit this invective is directed towards Philips toothbrushes, and Braun may be better. I just have to hope that Braun have got it right. But with the ridiculous prices of rechargeable brushes I can't afford to experiment. Gaaarrrhhh!
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