Charging Phone Electromagnetic Induction

Discussion in 'General Electronics Chat' started by Jbuzz, Aug 29, 2010.

  1. Jbuzz

    Thread Starter New Member

    Aug 29, 2010
    I am interested in finding out about ecoupling and electromagnetic induction charging.
    I bought a Palm pre Touch stone charger and am going to have a look inside the charger to see how it works.
    If anyone is a knowledgeable on this type of technology I would like to get in hear from you and ask some questions.


  2. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    Some electric toothbrushes use the same idea.

    It's basically a transformer with the two windings in separate housings. When you put them close enough to get good coupling, power is transferred.

    They probably also have some kind of monitoring so the powered side only powers up for brief pulses until it detects the charger circuit is loading it.

    The simplest DIY construction would probably be something like a ferrite 'pot core' with one winding in each half, so when the two parts are close together the magnetic circuit is made.

    You will need to use high frequency, some tens of kilohertz at a guess.
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    Could turn out to be dangerous if you don't know the inductances involved, you could end up inducing far more voltage into the phone than intended.
  4. Jbuzz

    Thread Starter New Member

    Aug 29, 2010
    thanks for your reply.

    The Charger that I am getting is already used for the Palm Pre mobile phone which uses a magnetic coil inside a touch pad. It it the same as the Power Mat that came out this year.

    I think it will be a simple process of following the same technique and principles and keeping it at 5 Volts.