pwm arduino

I have a couple questions about driving motors from the arduino (I have a boarduino) - First off, these motors are from various walkmans and I think each one is rated for 1.7 volts. - If I need a transistor, can i use a 2n3904 (since these arn't giant motors) - How do I protect against the emf? The motors need to work going either way (clockwise or counter clockwise) - How would you program it so that the motor can go either forward or backwards?

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guyfrom7up (author) 9 years ago
oh, and does anybody have an idea how to operate the lever of a zif connector using a cheap motor?
A servo-motor should do it pretty easily. Not cheap, though...
guyfrom7up (author)  westfw9 years ago
is there any devices thay would ustilize a servo that I could take apart? The only thing I can think of is some rc cars, and I can't find any.
not that I know of. Most cheap RC cars use some sort of cheap replacement where a more expensive device would use a servo. You might be able to get a stepper motor, perhaps with some gearing. (Mechanics always annoys me...)
guyfrom7up (author)  westfw9 years ago
me too, I have the motors, I just don't want to make the gearbox, i mean one gear box takes hours and hours.
westfw9 years ago
Do you have size restrictions? To do both directions, you typically need an H-bridge, which means 4 transistors, 2 each PNP and NPN. Or you could probably get away with a DPDT relay for direction (driven by transistor) and one additional transistor for on/off/pwm. Walkman motors are so efficient you might get away with driving them with logic chips, but I wouldn't recommend driving them from the AVR directly. Check the existing instructables on H-bridges, and/or the BEAM robotics motor driver archive
guyfrom7up (author)  westfw9 years ago
Thanks, checking it out. There arn't really and size restrictions, I'm building an automatic avr programmer, and it'll kinda resembles are really cheap cnc machine (like 10 dollars total.