I have an RC Car that I tore apart and I am attempting to rig it to an arduino.

The front wheels can turn left and right based on which way the current is flowing and the rear wheels will go either forward or reverse based on the current direction.

So the question is if they only have 2 wires coming off of them how do you rig a Darlington Tip 120 to it so it can go both forward and backward?

Or more simply put how do I control a motor that goes in 2 directions when it only has a positive and negative wire coming off of it.


Sounds like you are looking for information on an H-Bridge. The tip120 is an NPN transistor. H-Bridge uses 4 transistors. You'll need two NPN and two PNP transistors to create an H-Bridge capable of multi-directional motor control.

An H-Bridge works by allowing directional control of a DC motor by turning on two of the transistors at a time.

The choice of the two transistors decides which way current flows, dictating the direction of the motor.

Great tutorial here: http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge

Here's a tutorial using the tip120 http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto

  • \$\begingroup\$ Yup that's what I need. Just put in an order. Thanks! \$\endgroup\$ – Anthony Russell Sep 27 '13 at 2:57
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    \$\begingroup\$ It's also worth noting that you can get fully integrated H-bridge IC's like the SN754410, probably for less than the component parts would cost you. \$\endgroup\$ – Li-aung Yip Sep 27 '13 at 5:49

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