Connect with us

A kinetic phone charger project

Discussion in 'General Electronics Discussion' started by kostas, Oct 17, 2012.

  1. kostas

    kostas

    6
    0
    Oct 17, 2012
    Hello,

    in my school we are setting up an enterprize, which will produce kinetic phone chargers and sell them.

    The idea is that in a wooden box we'd fix a bearing with a magnet on it and put wound up magnet wire around it, the two terminals then would go to a 3.7V battery, then through a LED, a 5v voltage regulator, and into a usb cable which could charge phones.

    Could you please explain which wire of the solenoid would be positive and which negative, how should it all be set up, im probably missing a lot of resistors or capacitors.

    Id be greatful if you kept it simple, thank you. :)
     
  2. BobK

    BobK

    7,599
    1,641
    Jan 5, 2010
    A magnet going back and forth thorugh a coil will produce AC. You would need to rectify it. I also hope your customers are ready to shake vigorously for a couple of hours to charge their cell phones!

    Bob
     
  3. kostas

    kostas

    6
    0
    Oct 17, 2012
    Ok i have bought some rectifiers, what will they do to the AC and where should i solder it to,
    thanks
    Kostas
     
  4. BobK

    BobK

    7,599
    1,641
    Jan 5, 2010
  5. kostas

    kostas

    6
    0
    Oct 17, 2012
    Ohh yes, i remember these, it makes much more sense now, so i guess these will do
    so to take that a step further, if the battery is of 3.7V would you need to have some component inbetween the diode bridge and the battery? voltage regulator of some kind?
    thanks
    Kostas
     
  6. kostas

    kostas

    6
    0
    Oct 17, 2012
    Also would the diode bridge of 2Amps and 1000V be sufficient?
    Kostas
     
  7. BobK

    BobK

    7,599
    1,641
    Jan 5, 2010
    Yes, you would need a charging circuit.
    I doubt that 2 Amps or 1000V would be exceeded. If you have a multimeter, try putting a smoothing capacitor after the bridge and measure the voltage you get.

    Bob
     
  8. BobK

    BobK

    7,599
    1,641
    Jan 5, 2010
    By the way, I am probably being a little too subtle, but I don't think your project is realistic. However, I would encourage you to experiment with it and see what you learn.

    Bob
     
  9. kostas

    kostas

    6
    0
    Oct 17, 2012
    Its ok, i do want to acomplish it either way, it counts if you try, and it is interesting. How many uF should the smoothing capacitor be?
    Kostas
     
  10. kostas

    kostas

    6
    0
    Oct 17, 2012
    So, as i understand the voltage must be 3.7 and not more or less to charge the battery right?
    would a voltage regulator do?
     
  11. BobK

    BobK

    7,599
    1,641
    Jan 5, 2010
    No, Lithium Ion batteries are charged first with constant current until it drops off then a constant voltage of about 4.2V. It is not a simple circuit. However... You generator is not likely to produce the current needed to charge in constant current mode, but it probably could be used to "trickle charge" the battery, which is a lot simpler, but it will take many hours of shaking.

    Bob
     
  12. CocaCola

    CocaCola

    3,635
    4
    Apr 7, 2012
    If you want to charge modern phones through a USB cable you will need a regulated 5V for the USB at a minimum of 1A, 2A preferable for modern smart phones that will seek the higher current if available when charging, or else they will drop down to a real slow charge that will take extra hours...

    If you want to charge the 3.7V lithium batteries directly you will need to implement a lithium smart charger circuit, there are chips specially designed to do this...

    As hinted this is a fun experiment to educate yourself with but not real practical or realistic in the end...
     
    Last edited: Oct 17, 2012
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-