12VDC motor control

Hello and happy new year!
(1) I am trying to run a 12VDC motor using arduino and I’ve followed this tutorial(http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads)
But, my motor is not spining even if connect it in the same way the tutorial tells me to do.
At least, I think I’ve done it in the same way but i need your advise whether it’s been done correctly.
Below is the link to the photos.
http://www.flickr.com/photos/22334310@N06/?saved=1
The arduino is connected by USB. When it is connected to the computer, nothing blinks except power LED(Green).

(2)Also, I would like to know the most simplest motor control(simple motor on/off) method that is existing using arduino.
All I need is simple on and off motor control using arduino.
Could you let me know the even simpler way than this tutorial? (http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads)

from your pictures it looks like you are trying to control a servo motor. You can not control a servo with the TIP120 transistor / diode / resistor circuit. That circuit is ment for controlling an ordinary DC motor.

servo motors are controlled by continouslly sendeing then pulses to tell them where to move to.

Go here http://www.freeduino.org/ scroll down to the entries beginning with "s" there are serveral links to Arduino code for controlling servo motors.

Thank you very much for your comment. Could you tell me the most simplest and easiest and cheapest way to control DC motors' on/off mode withought using arduino? I would like to come up with such concept first to use arduino later on to control the on/off status of DC motor. I hope I could get some answer that I can follow right away.

For DC motors it's easy, just use a suitable powersupply and a switch, this will only give you on / off control, no control over speed or direction.

For servo motors you really need some electronics that can give the pulses they need to run. Many hobby shops selling RC planes / boats / cars have lot's of equipment for controlling servo motors

I have managed to control DC motor using TIP120 transistor and it spins fine.
But, the problem is that the transistor gets really really hot after just few seconds.
I want to use arduino program to turn on/off the motor, not using swich.
Isn’t there any way I could build a motor control circuit using arduino in a much more reliable way?
All I want to do is controlling on/off mode of DC motor using arduino.

you just have to make sure that the transistor you are using can handle the current the motor is drawing.

There are other transistors in the TIP series that can handle up to 2A (TIP31 if i remember correctly) if you put a good heatsink on them. But you could start by putting a heatsink on the TIP120 to see if that helps.

Another thing to do is to meassure the current the motor draws (if it is not printed on the motor) so you know what kind of transistor you should be looking for.

Edit : If the motor pulls more current than a transistor can handle, you can use the transistor to control a relay, and then the relay to control the motor.

Could you tell me how to measure how much current the motor draws? As always, thank you for your advise.

There is a tutorial here: http://www-education.rec.ri.cmu.edu/vex_online/lessons/current/docs/activity_one.pdf

But the basic idea is to connect a multimeter in series with the motor and power source. The meter must be able to handle the current draw of your motor. If you don't have a meter with the necessary current range, but you do have a voltmeter, you can connect a low value resistor (1 ohm is good) and measure the voltage drop across the resistor. Google ohms law if you are not familiar with the relationship between voltage, current and resistance.