Low-ish voltage motor drivers

I have a little electric car which I think will make a good platform for robot experiments. the two rear wheels are driven by separate 3v motors that draw a fair bit of current (guessing .5-1A).

I tried a simple driver circuit with a 2n3904 transistor but I guess the transistor can't push that much current thru so I decided to get a real motor shield. When I look at this one though RobotShop | Robot Store | Robots | Robot Parts | Robot Kits | Robot Toys it says 4.5V+ motors and others say 7V+ motors. Will these work ok with 3V?

This motor controller works virtually from 0-7V motor voltage:
http://www.robotsimple.com/Low_Voltage_Dual_Serial_Motor_Controller

Wow, at that price you could afford new motors and a bigger battery.

Yes but it would work and let me get on with this.

POOP - it's on backorder at robotshop canada.

Maybe a better idea is to get the adafruit shield which specs 4.5V and just stick a resistor or power diode in to drop a volt. At least then I can use the shield for a future project with the more traditional motors.

Ok. I'm going to try one of these:

it's cheap (if I ignore shipping) and although it specs 4.5V, the datasheet for the chip it uses http://www.semicon.toshiba.co.jp/docs/datasheet/en/LinearIC/TB6612FNG_en_datasheet_080509.pdf says the minimum voltage is 2.5V. So I can try a resistor, overdriving the motors, or underdriving the motor voltage inputs.

RobotSimple has free shipping worldwide.
You can also avoid "low order fee" of $3 by ordering over $15.
http://www.robotsimple.com/Motor_Controller_and_Driver

RobotSimple has free shipping worldwide.
You can also avoid "low order fee" of $3 by ordering over $15.

whoah, excellent source. thanks a lot!

You will need to make something custom for such low voltages.

Actually, no: the 4.5V minimum is for the Vcc supplies. After allowing for the drop across the Darlingtons, a 754410 or LM293 should output about 2-3V less than Vcc (depending on current draw). So a 5-6V supply should be about right for a 3V motor.

However, there’s a good chance that a 3V motor will draw more current than those 16-pin chips can safely supply: I’ve seen complaints about this from people who tried to use motor shields to control 3V toy vehicle motors. Especially when they didn’t add heatsinks.

oopsie, the little pololu driver board worked a treat but the poor little car can't move under the weight of the 2 AAs for the motor, a 9V for the arduino, the arduino and the shield. I'll try adding a battery I guess or some fresh alkaline AAs. So far I'm happy that it LOOKS the part anyway!