help me pick a motor shield

I am new to arduino and electronics in general.

The other day i bought this kit: http://toysdownunder.com/2wd-arduino-mobile-platform.html

which seems to be the same as described here: Arduino Playground - 2WDArduinoCompatibleMobilePlatform

in this kit there are 2 motors, which the wiki says are 3v-6v

however when i look in stores near me (i live in brisbane, australia), i can only find the following shields:

which say either 7-12V motors, or don't seem to specify at all.

can i use any of these shields with my motors?
if not, does anyone know where i can find an appropriate motor shield somewhere near to brisbane, australia?

p.s. i have a arduino mega (old style mega) can i just wire the motors directly to the arduino without a shield? (with minimal other components - maybe just some resistors?)

thanks for your help/time

i found the official (i think) site for those motors: http://www.dfrobot.com/index.php?route=product/product&path=47&product_id=100

however after reading more about those motors is am thinking i may be able to just use the PWM pins on the arduino to drive the motors.

any thoughts?

they are just DC motors so you can control them with the arduino pins. But you wont be able to control direction. Also you wont be able to plug them directly to the pins

a 6V motor can be run on 7V ( apply this only for motor's )

may be able to just use the PWM pins on the arduino to drive the motors.

pwm can be used to change the speed and even direction if you dont need to reverse the motors i.e switch off one motor ans make it turn or change the speed of different motors to turn softly

im confused.

if i connect my motor to the 5v and ground pins on the arduino it goes.

however if i connect my motor up to pin12 (for example) and ground it wont work - i have analogWrite(12, 255); in my code.

is this because the pins dont provide as much current?

The motors will take way more current than the arduino pin can source.

The motor shields that I've used can deliver way more voltage than toy mOtors want but as you say Pam will control it.

Sparkfun has a breakout board for a ti driver chip that I like very much. I'm using it with 3-4.5v motors and it's great.

is this because the pins don't provide as much current?

YES! check if your arduino is working :wink: the current limiting on each pin is around 40mA the motors run on Way more than that you will need to use a motor driver shield or a motor driver IC like that L298 do a google search for a h-bridge circuit or a pin-out for a L298

ok. I ordered a motor shield. so i guess since my motors are 3-6v and my power input (to VIN) will be 7.5V (5AA batteries) i just don't go up to the max value (255) when calling analogWrite();

is that correct? i guess i need to stay between like 100-200 with my calls to analogWrite?

Yes that will do good enough :wink:

Motor drivers based on the L293 and L298 families will lose about 2-3V between the battery and the motor (depending on current drawn, and chip-to-chip variations), because they use bipolar Darlington transistors to switch the power. So you may find that 5AA cells will not be enough, especially if you use NiMH. If you know you'll be using rechargeables, I'd plan on a 6-cell pack. Maybe even 7, to ensure that you're still getting enough power when the voltage drops a bit as the cells discharge.

the battery holder thing came with the motors so i would think it would be ok. but i guess we will see how it goes.

thanks for your help