Tuesday, November 28, 2006


Stepper Motor Improvements

The stubborn stepper motor has been conquered. Borrowing a 12V supply let me find a stepper sequence that doesn't skip. It's made out of discrete logic chips and Darlington transistors since that's all I had handy -- you can make interesting stuff out of a 7474, 7404, and 7400. Speeds shown are 1 step per second, 10 steps per second, and 100 steps per second. Next, half/double-stepping...

Wow! That's a hell of a breadboarded system you've put together there. Is that a bipolar or unipolar stepper motor?
I didn't build the breadboard -- believe it or not, the local university threw out about 6 of them! They're quite handy. They must have been for microprocessor training -- 5V supply, LEDs labelled things like MSB and LSB, oscillator, momentary and double-throw switches... Also note that I'm not using any of the chips on the upper board, just the three in that rats nest on the lower one. They drive those four big transistors to the left of them.

It's a unipolar 5-lead stepper.
//a 7474, 7404, and 7400//

What's really scary is, I knew exactly what these were as soon as I read it. I even had the pinouts for two of them pop into my head. Amazing the things you absorb over the years.
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