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  • Replies 12 replies
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  • transistor
  • help
  • rc
  • please
  • buzzing
  • motor
  • arduino
Related

Transistor Help

e14 Contributor
e14 Contributor over 12 years ago

I'v bin working on an arduino powered rc robot, I'v pulled out the old chip and my arduino is plugged into the motor via transistor and pins, the transistor has an external supply and grounds are connected but, all it does is make a weird buzzing in the motor. the buzz does change tone witch makes me think the arduino is doing something. I will put my code and pic of wiring below. please help.

 

     1k resistor and the transistors # is 2N 2904 331 and the power supply is a 6v rechargeable that came with the car

image

 

int motorPin = 9;

 

 

void setup(){

  (motorPin, OUTPUT);

}

void loop(){

  analogWrite(motorPin, 255);

  delay(1000);

  analogWrite(motorPin, 200);

  delay(1000);

  analogWrite(motorPin, 100);

  delay(1000);

  analogWrite(motorPin, 0);

  delay(1000);

}

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  • Robert Peter Oakes
    Robert Peter Oakes over 12 years ago

    A jelly bean ULN2003 with all the inputs and outputs paralleled may be good enough or my favourite is an N Channel Power mosfet with Logic level input, just a resistor from arduino to gate to limit inrush to the capacitive gate and your pretty much done

     

    Peter

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  • Robert Peter Oakes
    Robert Peter Oakes over 12 years ago in reply to Robert Peter Oakes

    http://www.farnell.com/datasheets/245431.pdf  is such an example

     

    http://canada.newark.com/fairchild-semiconductor/fdb7030bl/unknown/dp/58K1411?ost=FDB7030BL

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  • dougw
    dougw over 12 years ago in reply to Robert Peter Oakes

    Looks like a great FET Peter. If it can be switched fast enough, it might not need a heatsink.

    The motor probably needs a snubber diode to be safe.

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  • Robert Peter Oakes
    Robert Peter Oakes over 12 years ago in reply to dougw

    yup, I have done this with LED strings of many amps load with no heat sink and no detectable heat rise even in PWM scenarios so yes, a great part to keep in the spares bin as it is so easy to use

     

    I agree about the snubber but if you look to this :- it already has one, though no harm in adding additional ones to be safe if its rating is not enoughimage

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  • dougw
    dougw over 12 years ago in reply to Robert Peter Oakes

    I think the snubber diode needs to be across the motor, otherwise the drain voltage could go very high - assuming the motor is connected to the drain.

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  • Robert Peter Oakes
    Robert Peter Oakes over 12 years ago in reply to dougw

    Obviously i have not had enough coffee today

     

    Absolutely correct, +ve to motor, motor to drain, source to ground + snubber diode pointy end up to +ve across the motor image

     

    Peter

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  • e14 Contributor
    e14 Contributor over 12 years ago in reply to dougw

    I Used a  larger transistor and the motor now moves and varies but I can't turn it fully off

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  • dougw
    dougw over 12 years ago in reply to e14 Contributor

    If it is a PNP transistor, it may need a diode between the arduino and the base of the transistor.

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  • e14 Contributor
    e14 Contributor over 12 years ago in reply to dougw

    I googled the part and it said is a voltage regulator is that any different then a resistor? Part: l7805cv

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  • dougw
    dougw over 12 years ago in reply to e14 Contributor

    Yes it is quite different from a resistor - a voltage regulator outputs a fixed voltage - it is not a switch like a transistor either - it won't turn off the motor. It sounds like you connected the ground pin of the regulator to your arduino. This component and this circuit is a long way from doing what you want. Peter's description of a FET transistor circuit should work fine. Or there are many simple arduino motor driver circuits described on the internet.

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  • dougw
    dougw over 12 years ago in reply to e14 Contributor

    Yes it is quite different from a resistor - a voltage regulator outputs a fixed voltage - it is not a switch like a transistor either - it won't turn off the motor. It sounds like you connected the ground pin of the regulator to your arduino. This component and this circuit is a long way from doing what you want. Peter's description of a FET transistor circuit should work fine. Or there are many simple arduino motor driver circuits described on the internet.

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