While worth buying to test the Adafruit Motor/Stepper/Servo shield and get some hands-on experiments done I suspected the Solarbotics GM17 might not be the best motor for the job(s) in the Modular Music Box – requiring +9V, having little torque at low speed and being quite noisy – though it is quite compact and did just manage to fit centrally in the monome size casing alongside an Arduino Duemilanove clone…

Further research suggested that a stepper motor would be the best choice to drive the sequencer and animation turntables. In the interim I tested a stepper motor from Fab Lab Manchester – the six wire PF35T-48L4 – a 7V (though it will supposedly run as low as 5V) 20ohms UNIPOLAR, S/A 3.6deg stepper motor. The makingthings.com Stepper Motor How-tos helped me identify the yellow and orange as one pair, the black and brown as the other and the red and green wires as the center taps.

A search for potential UK suppliers led me to EMS (Electro Mechanical Systems) Ltd whose thorough online documentation and helpful sales team enabled me to select a Nidec Servo Corporation KH39EM2-851 bipolar phase stepper motor – which at 39mm square and just 20.8mm thick and a 3.6V operating voltage seemed to be the optimal model – and it was in stock and £36 + VAT with free postage – result. It certainly seems a solid, quality piece of kit…

Issues to resolve are whether with a 3.6V rating it will actually run with the Adafruit Motor/Stepper/Servo shield – designed for motors 4.5V and upwards… and how to power this with a consistent 3.6V supply – perhaps directly off a LiPo 2000mAh 3.7V battery?

The Adafruit FAQ is non-committal:
“Can this shield control small 3Vmotors?
Not really, its meant for larger, 6V+ motors. In theory you should be able to get it working with 3V motors but I have no information on how to do so or whether it will work.”

Searching for alternative shields/boards that might work with 3.6V motors offers limited options:

• possibly the Arduino Motor Shield (Kit)
• a non Arduino based – Basic 2 Channel 2A Motor Controller Board

A more in-depth search through the RobotShop Stepper Motor Controllers page might be called for…