I’ve been intending to try driving Switec X25.168 motors using the MCP23008 I²C I/O port expander chip from an Arduino, but it occurs to me that it might be more interesting to try this on a Rasberry Pi. If it works, it will demonstrate a simple and very inexpensive method for driving analog gauges from the Raspberry Pi without the need for high-current drivers.
Phil Bambridge has blogged about his Beverage-o-Meter which demonstrates wireless remote control of an analog gauge using Arduinos eqipped with Nordic 2.4GHz radio boards. Fun, whimsical, and beautifully housed too. His project uses a Switec stepper for the gauge, and uses the SwitecX25 library. Check out his blog and source code here.
I am aware of three companies manufacturing compatible motors. All appear to produce a good-quality product.