Small DC motors + clueless idoit = Erm . . .

Forum 2005-2010 (read only) Hardware Interfacing
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Well I've always been into programming with C-variants. In fact I'm confident I could program just about anything. So when a friend gets me an arduino microcontroller as a gift that allows low power electronic devices to be controlled using programs compiled from a c-like language I'm thinking cool this should be fun.

Turns out there's one little snag. I know nothing about electronics. My knowledge is very basic. Even worse I have no practical experience implementing it. I (think I) know the basic functions of resistors, capacitors, transistors, diodes, etc . . . I've been reading anything I can on anything, Done most of the example sketches (played with flashing leds). I've built some shield kits but I don't learn anything from something I've only assembled.

Now I'm interested in controlling some small 1.5-3v dc motors. They draw a max 700 mA. I (think I) know the arduino probably couldn't support that load. This means that I'm probably going to need to use a transistor somewhere. Using a 5v logic pin to control 1.5-3v seems backwards to me. What power supply for the motor would be good? two AA batteries seems fine? How does the grounding work with the logic pins? Would I just run a wire from the negative terminal of the battery into one of the Ground pins on the arduino? That doesn't sound like a smart idea. What is an H-bridge and how does it work? If it's a simple enough circuit, I'd be much more interested in making one then buying one.

How exactly would I control (hardware wise) a DC motor via the Arduino?

Thanks for your time

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You do need "something" inbetween Aduino and the motor. Arduino pins can source 40 mA max.

What "something" you need depends on how much current wil need to be controlled, and also on wether you need to only start / stop the motor or also to control direction.

In the simple case with only start / stop you could do it with a simple transistor (+ diode + resistor) solution. A TIP120 transistor would be a good choise, but many others are just as good.

If you need to control direction you need an H-bridge. H-bridges are essentially a bunch of transistors (somewhat simplified explonation here :slight_smile: ) and you could build one your self, but if your experience is minimal, the go buy one, the savings would not be much.

Try to google Arduino + DC motor or Arduino + TIP120

That will give you many links to schematics and code.

I can highly recomend Tom Igoes book "Physical computing", it shows you how to hook just about anything up to a microcontroller.

He is not using Arduino but some other micro controllers, but the electronics could be used directly with Arduino, and since C programming is not a problem for you, you would quickly solve any code issues. Its a REALLY good book!