Can I connect 4, 12v DC motors to arduino Uno?
What is motor driver ?
I read that the UNO board have 6 pwm, that mean that I can connect 6 motors, or two?
If I understand the pwm connect to motor driver and than the motor driver control the motor by extranl power source?
And I saw that most of the motor drivers can handle up to 2A, what I can do if the motor needs more than 2A ?
1)yes, with a motor driver
2)Something that allows you to control a motor (this may work: http://www.vexrobotics.com/276-2193.html)
3)With #2 yes, but you can do more with a bunch of h-bridges(eg.http://www.ecelab.com/circuit-motor-control-2.htm)
Do you need to run the motors in one direction only, or in forward and reverse?
If in one direction only, then it's easy, you can control each one using a mosfet driven from a PWM pin.
If in both directions then you need an H-bridge per motor. There are dual H-bridge chips available. Pololu makes good motor controllers, for example this dual motor controller Arduinio shield: http://www.pololu.com/catalog/product/2503.
thanks for the replies 
i need to run the motors both forward and reverse,
the motor current is 7.75A at full load and 12v, so i will need something that support up to 8A, do you know something like this?
(this is the motors that use : http://www.ebay.com/itm/RS-550PH-Motor-12V-DC-14-100-RPM-High-Power-550-Size-DC-Motor-Nichibo-/280976231186?pt=LH_DefaultDomain_0&hash=item416b7d0b12)
there is a motor shield the can move the motors both forward and reverse and can support 12v (from extrnal power source) and 8A ?
Go to www.pololu.com and search for "motor driver". This dual one Pololu - Dual VNH2SP30 Motor Driver Carrier MD03A may be suitable.
IdanAbutbul:
thanks for the replies
i need to run the motors both forward and reverse,
the motor current is 7.75A at full load and 12v, so i will need something that support up to 8A, do you know something like this?
(this is the motors that use : http://www.ebay.com/itm/RS-550PH-Motor-12V-DC-14-100-RPM-High-Power-550-Size-DC-Motor-Nichibo-/280976231186?pt=LH_DefaultDomain_0&hash=item416b7d0b12)there is a motor shield the can move the motors both forward and reverse and can support 12v (from extrnal power source) and 8A ?
8A isn't enough, IMHO - I would personally go for something around 10A...
cr0sh:
IdanAbutbul:
thanks for the replies
i need to run the motors both forward and reverse,
the motor current is 7.75A at full load and 12v, so i will need something that support up to 8A, do you know something like this?
(this is the motors that use : http://www.ebay.com/itm/RS-550PH-Motor-12V-DC-14-100-RPM-High-Power-550-Size-DC-Motor-Nichibo-/280976231186?pt=LH_DefaultDomain_0&hash=item416b7d0b12)there is a motor shield the can move the motors both forward and reverse and can support 12v (from extrnal power source) and 8A ?
8A isn't enough, IMHO - I would personally go for something around 10A...
Ok, and what is Stall Current 60A, Means?
It means that when the motors start up from standstill, they will each draw 60A. Also if the motor is prevented from rotating, it will try to draw 60A.
I suggest you choose a motor controller with built-in current limiting, to constrain the startup current to a more reasonable value. It's possible to use the Arduino itself to do the current limiting if you choose a motor controller with current sensing, but then you need to get the software right or you risk damaging something.