some help with a generator and a radio

Discussion in 'General Electronics Chat' started by Radec, Apr 16, 2007.

  1. Radec

    Thread Starter New Member

    Apr 16, 2007
    3
    0
    Hi all, so here is what I'm trying to do I have a bike light generator and I want to power an fm radio with it. The generator is 6V 3W and I picked up a really crappy radio from good will that takes 3AA's and says its 4.5V. Anyway whats the easyiest way to do this?

    It sounds like the generatro might be AC so I would need a rectifier and a zener diode? Or maybe its dc and I could just use a voltage regulator...or maybe it could work with none of this? please help thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The genny is probably DC, but the output will be way up and down with speed. You might get somewhere with a diode and big capacitor, followed by a regulator. A 7805 would probably do fine. Since you don't want to have the radio go dead when moving slowly, you might try one of those ultracaps that are over 2 farads at 5.5 volts.
     
  3. Salgat

    Active Member

    Dec 23, 2006
    215
    1
    Is it possible to do some sort of rechargeable battery type deal? I'd like to expand upon this. What would you do and what kind of battery would you use.
     
  4. Radec

    Thread Starter New Member

    Apr 16, 2007
    3
    0
    cool thanks for the replys...I was guessing that the genn would be DC

    @beenthere your reply is helpful, although I really don't know much about all of this so I don't understand it all, but I'll try and research what you said.

    I don't know if this is too much to ask but if anyone knows exactly what I would need and how to put it together that would be great.

    thanks again

    rad


    EDIT: @ a mod: I just relized this post might be better in the 'The Projects Forum', if you feel that it would be and would like to move it please do, sorry my mistake. thanks
     
  5. Radec

    Thread Starter New Member

    Apr 16, 2007
    3
    0
    would it be worth trying this with just the voltage regulator and not the capcitor.....just to see if the radio would turn on?

    rad
     
  6. CATV

    Member

    Apr 17, 2007
    11
    0
    The genny will probablt run the radio and the Cap will probably keep it going when you slow down. Problem is, the price of a 2 farad Cap will buy a lot of batteries. imho
     
  7. Salgat

    Active Member

    Dec 23, 2006
    215
    1
    If you dont care about the volume dying out if you slow down then ya go for it. Just be sure that its the kind of radio that automatically plays once its powered(doesn't require to be turned on everytime you unplug and replug it).
     
  8. wireaddict

    Senior Member

    Nov 1, 2006
    133
    0
    I had a bike with a generator a few decades ago & it seems that it was actually a 6V [RMS] alternator. I'd hate for you to toast your radio or voltager regulator; do you have a multimeter [or VOM]? If not, you really should get one if you want to persue electricity as a hobby; anyway, with the generator turning at a moderate speed, set the meter for the next highest scale over 6V. Set the meter to DC volts & connect the test leads to the generator output, then reverse the leads; if the generator output is DC the meter will read around 6V with the leads connected one way & will read negative [or try to if it's an analog meter] with the leads switched. Make sure you mark which terminal is negative & which is positive on the generator.

    If the meter doesn't read on DC volts then the output's probably AC, switch to AC volts & try it again; you should get about 6V regardless of meter polarity. If so you'll need to add a diode bridge to change your output to DC as mentioned in the other posts.
     
  9. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    if you really like to tinker with electronics, go ahead follow their advices but the most practical approach is a rechargeable batt as salgat mentioned. and let your gen take care of your lighting system if there is.

    moz
     
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