Modifying cheap RC car for son, need help

Discussion in 'The Projects Forum' started by synysterjoe, Dec 14, 2012.

  1. synysterjoe

    Thread Starter New Member

    Dec 14, 2012
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    Hello, I could really use some help. I have little electrical experience beyond wiring, and no circuit experience at all, but i don't believe i'll need that for this project.

    Here's what i'm trying to accomplish. I want to put a larger, more powerful motor on this cheap RC car I got for my son for Christmas. The original one is tiny, and not much fun. If I ran more power through the circuit board, I'm sure I'll fry something, as it's made for 5 AA batteries, so what I was thinking was to use the feeds from the board to activate a relay to channel the power through to the motor.

    Now here's the rub. It looks as though the board reverses polarity to achieve reverse, so using the relay would only get me forward all the time. The only way i know it reverses polarity is because it only has two leads going out of the board and to the motor.

    Is there any way to retain reverse using a simple set up such as this?

    thank you in advance
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    The motor on the RC car is powered by something called an H-bridge which reverses the current.
    You will need two relays and some diodes so that each relay will only be activated when the current is in the proper direction.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    Do you have a replacement motor picked out yet?

    How much are you willing to risk the car's innards? I mean, you might be able to get a pretty good bump up in motor power (2X?) without ruining the existing circuit. Otherwise, the solution is a little complex as just described.

    Buying a different car might be the best option. Hand the old one down to someone that could use it.
     
  4. synysterjoe

    Thread Starter New Member

    Dec 14, 2012
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    The diode idea sounds good, would you be willing to draw a simple diagram of how i should route this?

    and replacement motor hasn't been picked out yet, but i was looking at radioshack's selection of motors, and I think one of those should work?

    EDIT: the power source will probably be a few 9 volts daisy chained together, that way they're easily replace when the time come, and cheaper than a rechargable.
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    9V batteries are a poor choice because they don't hold a lot of energy.
    You can get 6V seal lead acid batteries.
    I picked up a whole bunch of RS 6V NiMH battery packs for racing cars at a closeout sale. Part Number is 23-338A.
     
  6. synysterjoe

    Thread Starter New Member

    Dec 14, 2012
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    Last edited: Dec 14, 2012
  7. MrChips

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    Oct 2, 2009
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  8. synysterjoe

    Thread Starter New Member

    Dec 14, 2012
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    Yeah, unfortunately, times are tough, and for the money, I'd rather give him something a bit more personal. Sure it won't be the best, but I'll have put some of myself in it, and hopefully that makes this a bit more special. So, I sincerely appreciate the help with this guys...
     
  9. wayneh

    Expert

    Sep 9, 2010
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    No argument there. You might give him the parts, rather than the finished car, and then work on it together. It'll be memorable fun even if it blows up or crashes on the maiden voyage.
     
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