Induction Coils PLEASE HELP

Discussion in 'The Projects Forum' started by chris200408, May 14, 2009.

  1. chris200408

    Thread Starter New Member

    May 11, 2009
    4
    0
    I am building the battery charger below. I want to charge 4AA batteries. I also want to replace the transformer and make inductive coils in order to inductively charge the batteries.

    http://www.elecfree.com/electronic/wp-content/uploads/2007/07/charger.gif

    I was thinking of doing a 17:1 windings ratio in order to have about 110Vac in and 6.5Vdc out.

    I was just going to wrap my own coils (I have access to a coil winder). Does this sound correct? All i was going to do is wrap copper wire and insulate it. Is there anything else that I need to do? Thanks so much!

    I am also a little confused on the reversed polarity of the coils. How would I do that?
     
    Last edited: May 14, 2009
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    That "inductor" you are referring is just a plain power transformer. I would strongly advise you not to wind your own power transformer because the result can be dangerous and would get someone killed if not done correctly.

    Don't mess with high voltage AC mains.

    Besides, power transformer with low voltage 1A secondary for this application is so simple, cheap and available everywhere in the world. There is not much point in trying to wind one yourself.
     
  3. chris200408

    Thread Starter New Member

    May 11, 2009
    4
    0
    I think you misunderstood me. I know that it is a transformer, but I want it to be inductive. I do not want the physical connection between the two. The point is that we have a robot car. I want the car to drive up to a "charge station". The car will have a coil with the ac-dc converter to charge the batteries, and the station will have a coil attached to a 110Vac source.
    The issue is, I cannot seem to find very nuch information on inductive transformer design. Is it exactly the same as regular transformers. Right now, I basically have done the N1/N2=V1/V2=I2/I1 equations to find my ratios.
     
  4. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    You have indeed made that clear in your first post. I'm sorry to have misread it.

    Have you ever thought of do it by frequency higher than 50Hz, maybe 100KHz or more? The physical size of your inductors can be smaller, like those we found in electric toothbrush.

    You can also find a lot of additional information if you search the phase "splash power" in Google.
     
  5. DonQ

    Active Member

    May 6, 2009
    320
    11
    The coupling between the two windings will be much less in the configuration you are suggesting. The type and size and configuration of the core(s), and the distance and alignment between them will all affect the coupling between the two windings.

    Even just taking the cap off the windings on a, otherwise working, small transformer is likely to make the transformer smoke instead of "transforming". This is the mode your charger will be operating in when the car is not present.

    It might be worth just using the workings of an existing device, like a rechargeable toothbrush, shaver, or something similar. Even these use things to ensure that the separate components are closely aligned when charging.
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    So you are going to make an air core transformer. You can increase the frequency of the mains voltage as to use smaller components in the ac-dc converter on the car. Of course this will cost you a more complicated circuit on the station but you will make the car lighter.
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    Partially successfull experiment: Disassembled a 10W ??, audio line transformer, re-stacked laminations to make an E core. Replaced windings, connected AC line to O & 2000Ω winding. Car coil E made up of 1/2 X 1/8 strap iron[ mild steel], poor substitute, but all I had. Used 50 turns of # 26 magnet wire for test, about .3Ω. With no spacer = 1.6V, or about 220 turns ;with .15 in spacer = .4V or 1000 turns for 7V. If seperation could be reduced to around a 1/16 in, might be dooable, especially if frequency could be boosted.
     
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