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Vibration Motor on a Prop — Parallax Forums

Vibration Motor on a Prop

BenClarkBenClark Posts: 20
edited 2010-09-07 19:05 in Propeller 1
I am working on a project using the Gadget Gangster Prop Module SD.
The device will be in a small hand held case and I need to give the user some feedback.
I would like to do this with a small Vibration Motor.
http://www.pololu.com/catalog/product/1638/specs

I am fairly new to all this so my question is as follows.
The Propeller pins has a 40 mA max.
The Vibration motor pulls 60 mA.
If I understand all this correctly, I cannot connect the vibration motor directly to the CPU pin.
I'll need to have a switch (ie relay) connected that will turn the vibrator on and off.

Is that correct? If so, any recomendations? Relay, Transister, ????

Thanks in advance.
Ben Clark

Comments

  • LeonLeon Posts: 7,620
    edited 2010-09-07 14:11
    Use a transistor (BJT or MOSFET). I'd use a 2N4401, as the starting current of the motor can be quite high. You also need a diode across the motor.
  • jmspaggijmspaggi Posts: 629
    edited 2010-09-07 14:13
    Hi Ben,

    It's not only 60mA. Look like at 3.3V it can go up to 80mA (See notes).

    The simplest solution here is to use a transistor. Don't need a relay for that.

    Just put a 2N2222 between your propeller and your motor, and that will do the job.

    JM
  • Nick McClickNick McClick Posts: 1,003
    edited 2010-09-07 14:17
    It's a bad idea to connect a motor directly to the I/O. I've attached a little circuit on how to do it with an NPN BJT (like a 2n3904, although I don't know the max current for that). Haven't tested it out myself, but it should work for your circuit.
    motor_circuit.png
    347 x 440 - 4K
  • BenClarkBenClark Posts: 20
    edited 2010-09-07 14:18
    Just what I needed.

    Thank you both for the quick reply.
  • BenClarkBenClark Posts: 20
    edited 2010-09-07 14:19
    Wow! Thanks guys!
  • LeonLeon Posts: 7,620
    edited 2010-09-07 14:21
    The starting current could be 200 mA or more, at a guess, which is why I suggested something beefy like a 2N4401. Don't forget the diode, you could zap the Propeller without it.
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-09-07 19:05
    Leon wrote: »
    ... Don't forget the diode, you could zap the Propeller without it.

    What Leon is talking about is a flyback diode. See the following for more info:

    http://en.wikipedia.org/wiki/Flyback_diode

    :)
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