Arduino + simple DC motors? (4WD kit)

Question

I am trying to connect 4 small DC motors to Arduino, like those in the following image: my kit, 4WD, with 4 simple motors

The specification for each of them is:

Suggested Voltage: 3V DC;
No Load Speed: 65 ± 10rpm;
No Load Current: 125mA (170mA MAX).

But I have no useful knowledge in electronics to do so...

I would be really thankful if anyone could explain me why it is so difficult to connect DC motors to Arduino (I've heard about problems with the magnetic field, but I don't really understand why); and possible point me to an easy (and cheap) solution. I am, of course, willing to study (not expecting a complete solution).

I'm aware there are some shields for doing this kind of connection, but they are really expensive, and I've seen some people using only transistors or components like SN754410.

Thank you in advance! :-)

• Chris Stratton: It's not really the no-load current you need to know, but rather the load current. Those look suspiciously like the type of low-voltage, high-current motor which is hard to drive, such that many people replace the actual motors in the gearboxes with others. But if you want to try, consider an FET H-bridge like the TB6612FNG, probably already on a PC board.
• user282723: @ChrisStratton, thanks! I am planning on using a L298N driver motor; wiring the two left motors together and the two right motors together (being able to use a single dual H-Bridge). Would you happen to know if this configuration would suffice? :-)
• Magic-Mouse: may i ask where you got that kit ?
• Chris Stratton: I would not use the L298 in a battery powered application - the losses are a bit high, in particular you will drop more than a volt across the two transistors.
• user282723: Thank you, guys! I have used the L298 and it was perfect. :-)

Answer 1

First you make 4 parallel H-Bridges, http://en.wikipedia.org/wiki/H_bridge then you attach it to an external powersource ( or attach directly to the battery to prevent burning your arduino )

Attach every up to a pin, making it high makes the motor running, you need 8 pins for this, eg pin 1 makes motor 1 go forward, pin 2 makes motor 1 go back and so.

This is by far the most practical solution, but it is the easiest, and can be done with 8 PNP and 8 NPN transistors.

If you don't know how transistors work i suggest https://www.youtube.com/watch?v=-td7YT-Pums collins lab, it is both educational and entertaining.

• Chris Stratton: Making your own H bridges from discrete transistors is probably not the best solution here, especially for a poster facing this for the first time.
• Gerben: Just wire 2 motors to turn forwards, and 2 to turn backwards. That way you don't need an H-bridge (which in theory is easy to make, but in practice can be difficult to do right, I'm told).
• Magic-Mouse: @Gerben true true, but this is 4 motors attached, i was just afraid that the current going through them would be more than the arduino could handle, thats all. (Besides it is fun to play with H-Bridges, since it is the first step for a stepper motor. No pun intended)
• Magic-Mouse: @Gerben The Arduino does not handle more than 40mA on an IO pin (according to documentation) and 200mA on the Vcc pin meaning he could only run 1 motor or risc frying the board.
• Magic-Mouse: Yes the L298N is perfect for that since it supports up to 4 amps of current so you could serial couple about 23 of those motors without frying it.