help how do i step up4.5 to 9volts with circuitry no transformers please rc project

Discussion in 'The Projects Forum' started by commandertom, Nov 2, 2010.

  1. commandertom

    Thread Starter New Member

    Nov 2, 2010
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    any help greatly apreciated

    converted rc 4.5volt thomas the rail road to leg monorail but motor has tons of torq no speed

    the lego motor is meant to have a 9v battery to power it direct

    now its got 3 batts in series a positive and negative wire to the first batt +(1.5)-going to the recieverthen next in the series is (1.5)_(1.5)-wire all three leed to the micro cirut board the first red ,oarnge and black
    ichecked the voltage and the first two show olny 1.5 volts as they are hoked up to the firts batt for power to the reciever board
    the last wire black is 4.5 volst when linked to the first whicch is the pos tive for the reciever

    i tried hooking a nine vole ont the last leg and got nothin no functions

    al is well ti still works but is torqy and wold like to step up 4.5 to 9 volts

    a reciever powered by 1.5 volts and the drive motor 4.5volts
    when i increase the voltage to the motor legs of the circut which has for ward and reverse nothing works even thout the 1.5 leg is separte but shares positive to the micro prosessor
    any help aprecieated its a suprise lego monorail for x mas now to be rc monorail for my son thnks:cool:
     
  2. t_n_k

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    Mar 6, 2009
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  3. SgtWookie

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    Jul 17, 2007
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  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Stacking several 9volts in parallel wouldn't use up much more room than the AA's. Radio shack carry's 9volt connectors with pre-tinned and stripped wires, ready to solder to. 4 or 5 in a pack should provide enough current to run the motor for several hours. Spending on the front end and going with rechargeable would mean not having to buy constant replacements. You sure you don't have room to squeeze them in somewhere inside the toy? :)

    Another choice is spending the 10 to 20 plus shipping for a motor that runs well at 4.5 volts. Turns out, that is about what four 9 volt batteries cost. ;)
     
    Last edited: Nov 2, 2010
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  5. SgtWookie

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    A typical alkaline 9v battery has a ~525mAh rating. NiMH/NiCD 9v batteries are typically 120-150mAh. AA batteries are typically 2200-2500mAh. You certainly get a lot more for your money with the AA batteries.
     
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  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Sarge is correct with the batteries.

    The only "Decent" 9V I've dealt with are the Lithium which run with 3x3V Lithium inside, they do last a while, but are nowhere near the value for power that AA batteries have reached. The Lithium 9V are still near or over $10!
     
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  7. iONic

    AAC Fanatic!

    Nov 16, 2007
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    If that Lego motor runs off a single 9V Battery, I would think that doubling the 4.5V source could produce as much current as the 9V Battery can. I wouldn't think that you'd be drawing more than 200mA from that 9V Battery. Something like the following part...

    http://www.national.com/profile/snip.cgi/openDS=LM2735
     
    Last edited: Nov 2, 2010
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  8. commandertom

    Thread Starter New Member

    Nov 2, 2010
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    i looked at som video on paralell rc ciruts and teroies that a resistor acros negative and positve terminals will change the sine wave form and draw more current how that will make the motor spin as if it had 9 volts dont know but ill try it
    what do you think?
     
  9. commandertom

    Thread Starter New Member

    Nov 2, 2010
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    the little rc device runs on 3aaa batterys in series creatin 4.5 volts the receivers mother board is ran of the first batt in series at1.5 volts but i cant change the voltage going in to 9 because the chip wont oprerat at that level olny 4.7 or lower output to the motor is 4.5 volts in paralell

    and switching polarity for forwrd and reverse

    i watched the vide on rc paralelle circuts and surmised that the old motor had a campacitorbridge across +& - that must lower the voltage and increase the amps i need to do the oposite do you thik thats right after watching the video on parleel rc ciruts

    thnks RobΩ
     
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