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Motors not spinning in RC Car

Discussion in 'Sensors and Actuators' started by TimeManx, Apr 8, 2011.

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  1. TimeManx

    TimeManx

    31
    0
    May 11, 2010
    Hi guys, I'm building a basic RC Car. There's an LED in the receiver circuit which lights up when I press a button on the remote. But when I connect the motors, it stops lighting and neither do the motors spin. It just spins on the first button press after connecting the batteries (the LED also blink dimly) and not after that.

    Attached the schematic for the receiver section.

    Thnx

    EDIT: Corrected the schematic
     

    Attached Files:

    Last edited: Apr 8, 2011
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Are those KA7805's voltage regulators? If so, they appear to be connected incorrectly.
     
  3. TimeManx

    TimeManx

    31
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    May 11, 2010
    Yea ur right. Uploaded the corrected schematic.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,361
    2,757
    Jan 21, 2010
    OK, It still looks wrong.

    For a 7805, pin 1 is connected to +ve, Pin 3 is 5V output, and pin 2 is the common which must be connected to gnd (-ve in your case).

    It is also convention to draw the +ve rail at the top of the diagram.

    I'm also curious as to why you need two 5V regulators?
     
  5. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    The 7805's look right to me now (apart from conventions, and the 0.1pF cap) though I haven't checked the other IC pinouts & data.
    It's usual to keep motor and receiver supplies separate in RC applications.
    What's the main battery voltage/power? How much current does the motor draw? Do you have a multimeter?
     
  6. TimeManx

    TimeManx

    31
    0
    May 11, 2010
    currently im givin a 9V supply and using two 6V motors. but ive tried using 3V motors too with the same result.
     
  7. TimeManx

    TimeManx

    31
    0
    May 11, 2010
    yea i have a dmm
     
  8. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    9V should be ok, but what kind of power is it capable of delivering? Also, motor voltage has (almost) nothing to do with the matter, it's the power draw that counts.

    Start with measuring the 9V supply first, it shouldn't drop below 7.2V. Then measure the 5V supplies.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,361
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    Jan 21, 2010
    Yeah. Must be some weird caching thing. I'm still seeing the wrong (original?) diagram. I thought that the motor was running from the unregulated supply but it's just the catch diodes that are being returned to it.
     
  10. TimeManx

    TimeManx

    31
    0
    May 11, 2010
    btw its .1uF
     
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