Electric Toothbrushes: Charging Plastic Casings

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Discussion Overview

The discussion revolves around the charging mechanism of electric toothbrushes, specifically focusing on how charge passes through plastic casings. Participants explore the theory behind magnetic induction and its efficiency in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions how electric toothbrushes charge through plastic casings, noting that plastic is an insulator.
  • Another participant suggests that magnetic induction is the method used, where energy is transmitted through an oscillating magnetic field.
  • A different participant challenges the efficiency of magnetic induction, asking why it would be used if it is less efficient than other methods.
  • It is mentioned that magnetic induction is considered safer, especially since toothbrushes are often used in wet environments.
  • Participants discuss whether the toothbrush contains a battery pack or a capacitor, with one confirming it has a battery pack.
  • One participant compares the charging mechanism to a transformer, with windings on either side of the plastic casing.
  • Another expresses surprise at the efficiency of producing a strong enough magnetic field for induction.

Areas of Agreement / Disagreement

Participants express differing views on the efficiency of magnetic induction as a charging method, and the discussion remains unresolved regarding the optimality of this approach.

Contextual Notes

Participants do not fully explore the assumptions behind the efficiency of magnetic induction versus other methods, nor do they clarify the specific design choices made in electric toothbrushes.

jimmy p
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How do electric toothbrushes charge? The ones i have seen are all plastic casings and the chargers are made of plastic, or at least the casing is. Obviously plastic is an insulator, so how does the charge pass through a plastic coating, and then through another?

Thanx
 
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Magnetic induction. Energy is carried through an oscillating magnetic field.

- Warren
 
Originally posted by mmwave Why would they seal it up and use the less efficient magnetic induction?
It's not that much less efficient, and it's safer.

- Warren
 
The point is that one tends to use a toothbrush in a wet environment, often with wet hands.
 
...ok then, so the charger has a powerful electromagnet inside it? does the toothbrush have a battery pack or a capacitor inside it?
 
battery pack
 
Just think about a transformer, with one set of windings on one side of the plastic, and one set of windings on the other.

- Warren
 
ok cool, that sounds cool. I am suprised that is efficient though, to produce a strong enough magnetic field to induce a charge.
 

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