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Help with 3v dc motor

Former Member

Hi, I have been attempting to get a 3v DC motor to work with my ardiuno with no luck. Im pretty new to arduino so its probably something stupid simple im missing. I have tried other tutorials on the inter-webs to see if maybe the book i was using had something wrong in it.

http://exploringarduino.com/wp-content/uploads/2013/05/549360-c04f003callouts-copy-150x150.jpg

The link above is the diagram provided by the book.

http://exploringarduino.com/content/ch4/

This link is the online material of the book im using.

arduino 3v dc motor setup - Album on Imgur

This link is of what i have done.

code is below.

-----------------------------------------------------------

const int motor = 9;

void setup() {

pinMode(motor, OUTPUT);

}

 

void loop() {

  for(int i = 0; i < 256; i++){

  analogWrite(motor, i);

  delay(10);

  }

  delay(2000);

  for(int i = 255; i>=0; i--){

   analogWrite(motor, i);

  delay(10);

  }

delay (2000);

}

---------------------------------------------------

 

Alright so everything i have tried so far is switching both the transistor (pn2222a) and the diode around in case i had them the wrong way and that is not the case.

I have measured the output of the transistor thinking that maybe it a was a faulty part and i get ~7 volts which i feel seems high. the transistor also gets really hot to the touch. If i put the multimeter up to any other part(diode, capacitor. motor) I get no volts. If I hook the motor directly to the ground then the motor will run at full speed.

Im pretty lost on what else to do any help will be greatly appreciated if you need better pictures or for me to test something just ask. Thank you in advance.

Parents
  • 0

    Thank you for the quick replys I am going to try everything you guys suggested when I get home later but I have one last question. I forgot to say above in the first post that when I take the ground of the motor and ground it with the rest of the circuit it will run at full speed. Is it possible that 9v is to much for the 3v motor when it is solely "attached" to the transistor? Also is there a way I can tell if i have destroyed the transistor?

  • 0 in reply to Former Member

    Hi,

    I think you may have fried your transistor. Since your circuit seems right to me I would suggest to do the simple led check.

    You need:

    One 1K resistor on the gate which goes to Vcc

    One led and a 330R resistor on the collector which goes to Vcc

    You also need to put the emitter to the ground.

     

    Then you should be able to make the led brighter by decreasing the gate resistor value (thus increasing the current) or fade the led by increasing it (less current).

     

    Hope this helps. Buy loads of transistor image It won't be the last you fry.

     

    Also I strongly suggest to switch to MOS-fet for fast switching application such as PWM for motor control. This type of transistor commute proportionally to the voltage put on the grid (not the current) which is handy when controlled by a MCU that cannot deliver much current. I strongly recommend you to invest into some BS170 mos-fet (https://www.fairchildsemi.com/datasheets/BS/BS170.pdf), which are perfect for general purpose use with Arduino (Vgs = 2.1 V ->3.3V compatible). If you don't mess up the wiring it is unlikely that you will fry them, keep in mind that the current limit is quite low with those = 1.5A at 3V Vdrain-source.

     

    I can't find what is going wrong with your setup. But I hope you won't be discouraged since electronic is so much fun, and frying stuff is ok, it almost doesn't cost anything at all image

    Good luck !!

Reply
  • 0 in reply to Former Member

    Hi,

    I think you may have fried your transistor. Since your circuit seems right to me I would suggest to do the simple led check.

    You need:

    One 1K resistor on the gate which goes to Vcc

    One led and a 330R resistor on the collector which goes to Vcc

    You also need to put the emitter to the ground.

     

    Then you should be able to make the led brighter by decreasing the gate resistor value (thus increasing the current) or fade the led by increasing it (less current).

     

    Hope this helps. Buy loads of transistor image It won't be the last you fry.

     

    Also I strongly suggest to switch to MOS-fet for fast switching application such as PWM for motor control. This type of transistor commute proportionally to the voltage put on the grid (not the current) which is handy when controlled by a MCU that cannot deliver much current. I strongly recommend you to invest into some BS170 mos-fet (https://www.fairchildsemi.com/datasheets/BS/BS170.pdf), which are perfect for general purpose use with Arduino (Vgs = 2.1 V ->3.3V compatible). If you don't mess up the wiring it is unlikely that you will fry them, keep in mind that the current limit is quite low with those = 1.5A at 3V Vdrain-source.

     

    I can't find what is going wrong with your setup. But I hope you won't be discouraged since electronic is so much fun, and frying stuff is ok, it almost doesn't cost anything at all image

    Good luck !!

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