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Phone Charger

Discussion in 'General Electronics Discussion' started by Korolija123, Jun 3, 2013.

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  1. Korolija123


    Jun 3, 2013
    I've seen a project recently about Bycicle Phone Charger. I've found schematics for it and the system uses 12V Dynamo Generator and I have one that generates 6V. In order for it to charge a phone it needs to be dropped to 5V. Here's the pic of the circuit
    I know, I could use diodes but that will drop voltage to 4.6 V. I don't want to damage my system with too much power but still I don't know if this is going to charge my phone. The schematic up uses 7805 regulator I believe but 7805 regulator requires 7V in order to drop electricity. Is there any other solution or I just connect two diodes (Or only one?)? :D

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    Last edited by a moderator: Jun 4, 2013
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Beware that a dynamo can generate very high voltages if operated without a load. These will kill the 7805.

    This will happen when the phone is disconnected or stops charging.

    I'm not sure what the best protection is. Perhaps a 5W 20V zener across the output of the rectifier?
    Last edited: Jun 4, 2013
  3. davenn

    davenn Moderator

    Sep 5, 2009

    was that supposed to be 5W 20V ?

  4. Korolija123


    Jun 3, 2013
    The circuit works fine for others... I think I've found a solution. Connect the car charger to dynamo through mechanism that is in the car. The car charger converts any voltage to 5V so, what do you think?
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