Motor shields worked well - but they cost around $50 each, more than the Arduino itself. That`s fine for a single one, but I`m teaching an Arduino workshop (this Thursday!) for high school girls, and I needed something I could buy more cheaply so I could get more of them. (Incidentally, if any women in the Bay Area want to help with the workshopthis Thursday, June 28
Click here to download the full size of the above Circuit.
2012, I could definitely use a few more helpers! Please drop me an email. ) What I found on the web and on the Arduino IRC channel was immensely confusing to someone who isn`t an electronics expert - most people recommended things like building custom H-bridge circuits out of zener diodes. But it`s not that complicated after all. I got the help I needed from ITP Physical Computing`s DC Motor Control Using an H-Bridge. It turns out you can buy a chip called an SN754410 that implements an H-bridge circuit - including routing a power source to the motors while keeping the Arduino`s power supply isolated - for under $2. I ordered my SN754410 chips from Jameco and they arrived the next day. (Technically, the SN754410 is a "quad half-bridge" rather than an "dual h-bridge". In practice I`m not sure of the difference. There`s another chip, the L298, which is a full h-bridge and is also cheap to buy - but it`s a bit harder to use because the pins are wonky and it doesn`t plug in directly to a breadboard unless you bend the pins around. I decided to stick with the SN754410; but the L298 might be better for high-powered motors. ) Now, the SN754410 isn`t as simple to use as a motor shield. It has a lot of wires - for two motors, you`ll need six Arduino output pins, plus a 5v reference and ground, the four wires to the two motors, and the two wires to the motor power supply. Here`s the picture of the wiring, made with Fritzing. With...
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