I scavenged a small stepper motor from a broken scanner and would like, as a matter of learning and discovery, to create a simple discrete-component driver for it.
My searching has come up with no promising ideas. I've looked up the datasheets for motors that _seem_ similar on DigiKey, and wired it likewise, but the circuit combined with the activation sequence of the different windings just makes it vibrate and hum. If I drive just two of the coils -- like yellow and orange -- it moves, but has almost zero torque, drawing ~15mA.
The motor has 5 wires: a common red wire (common ground?) with 26.6 ohm resistance to the others. The others are black, brown, yellow and orange.
It has little detent torque, but has nice holding torque when connected directly to 6V.
I'd like to control it with four pins from an AVR running at 5V, in a dual-power rail setup to understand how to do that.
Can anyone direct me to a simple transistor-based design so that I can get it running and measure its characteristics while running, to gain an understanding of what's going on?