How to control my 12V Fan with my raspberry?

If all you want to do is turn the fan on and off the circuit below should work.  I don't see any reason why it wouldn't work for PWM as well, but I haven't tried it.

Thank you! And I guess the arrows should be the input for the fan?

holy molie...

Dave - W6TE

Date: Fri, 5 Apr 2013 20:16:47 +0000

From: messages@element14.com

To: w6te@msn.com

Subject: - Re: How to control my 12V Fan with my raspberry?

    Re: How to control my 12V Fan with my raspberry?

    created by Stijn Verwoerd in Raspberry Pi - View the full discussion

Thank you! And I guess the arrows should be the input for the fan?

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The fan would be "M1" in the diagram.  The input from the pi board is "GPIO".

If you're just getting started, I would recommend using the Adafruit Occidentalis distro from http://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/

Adafruit also has a usable web ide for programming the pi .. http://learn.adafruit.com/webide

And there are a bunch of tutorials here: http://learn.adafruit.com/category/raspberry-pi

I´d really like to thank you for your help!

I really appreciate it!

I´m sorry this might be a very dumb question but I still don´t get what the ground should be hooked up to?

The ground (the downward triangles) connects from the negative terminal of your power source to the circuit.  You will also need a ground between the circuit and your board.

http://learn.adafruit.com/adafruits-raspberry-pi-lesson-8-using-a-servo-motor/overview
Would this actually be the same, or isn´t it safe enough when I´m using 12V?

also thanks!

http://learn.adafruit.com/adafruits-raspberry-pi-lesson-8-using-a-servo-motor/overview
Would this actually be the same, or isn´t it safe enough when I´m using 12V?

also thanks!

From a hardware standpoint this is closer.  As far as the software, there's a gpio lib in the Adafruit WebIDE .. you set the pin to 1 to turn on the fan and set it to 0 to turn it off.

Bruce

I'm curious why you have included a 100Ohm resistor in the emitter.

its inclusion will limit the amount that the Oi can turn on the fan, so it will never reach its full current of 100mA.

If the fan was able to switched on hard enough, then there would be 10v generated across it at 100mA, which would turn off the drive from the Pi.

By my calculation the maximum fan current will only be 27mA before the 3.3v from the Pi is unable to turn the transistor on.

My suggetsion is to remove the 100Ohm resistor as you already have a 1K in series with the base thereby protecting the Pi GPIO.

Mark

Good catch, Mark .. I thought up that circuit without doing any homework on it .. that'll teach me!

You are completely correct, with the 100 Ohm resistor on the emitter, the maximum current is limited to ~30mA.  Without the resistor, the circuit will supply >100mA