How to make a relay circuit

Hi every one,

Is there anyone know how to build up a circuit that's going to use the 5V Arduino output to control a 12V DC motor. by the way I don't want to use the motor shield and the input for that.

Thanks.

The question is not if anyone knows (we do), but the question is what do you want ?

What kind of current is that DC motor ? Do you want it to be able to rotate the motor in both directions ? Do you want to control the speed, or just on and off ? Why don't you want to use the motor shield ? A clone of the Adafruit Motor Shield is less than 5 dollars: http://www.ebay.com/sch/i.html?LH_BIN=1&_sop=15&_osacat=0&_from=R40&LH_PrefLoc=2&_nkw=motor+shield+-sensor+-car+-easydriver+-mini+-new&_sacat=0

If you want to use only a relay, you can choose either a transistor or a darlington transistor or a mosfet and add a opto-coupler. Or you can buy a relay module that can be used with the Arduino.

This picture is the most simple way to use a relay: http://forum.arduino.cc/index.php?topic=89649.msg672676#msg672676

1) Its 12 Vdc , 120 mA. 2) I want it to rotate in one direction. 3) just on and off 4) I don't want to use the motor shield cause its a school project and thats the instruction.

Just need a transistor then. See the connection on pin 17.