The ADM 0620 two-phase stepper motor from MicroMo Electronics Inc., (www.micromo.com), a company within the Faulhaber Group based in Clearwater, Fla., sets a new standard for compactness. The 9.3-mm-long motor has a 6-mm outer diameter and weighs only 1.4 gm. This makes it the smallest two-phase stepper in production, according to the manufacturer.

The motor runs on 3 to 6 Vcd. Angular acceleration reaches 165,000 rad/sec, which means it can have a power rating between 125 and 250 mW, depending on the operating mode.

The motors are usually equipped with one ball bearing and a sleeve bearing, but can be ordered with two ball bearings. Operating temperature range is from 40 to 70°C. Various controllers are available and customized ones can be developed to match any system. The company also makes a complimentary, 6-mm-diameter planetary gearhead. Reduction ratios range from 4:1 to 4,096:1, providing torque to 3.5 oz-in.