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Sub-gram DC Brushless Motor Controller
DC Brushless Motor Controller,
World's smallest motor and servo controllers for some of the world's smallest aerobatic planes
We measured the weight of our airplanes against the weight of potato chips.
Filling the micro-airplane niche in 1998, Dynamics Unlimited quickly became the most innovative source for ultra-lightweight radios, motors and servos.  This 1/2-gram controller was an excellent match for Dynamics Unlimited's 11-watt 5-gram motor.  Delivering over 60 grams of thrust, this motor was the engine behind an all-up 37-gram aerobatic model airplane.
Circuit design, PCB layout and software are exclusively my work.
 - On-board 25MHz MCU
 - Variable speed
 - In-flight reversibility
 - Very high efficiency
 - Automatic back-EMF start, no hall sensors or encoders needed
 - 2.9V-4.2V operating voltage
 - 3.5A continuous output
 - High-speed commutation to handle small motors (>10,000 RPM)
 - Accepts standard RC radio servo input
The servo originally used a flux gate to sense the position of a magnet embedded in the servo's geared motor shaft.  Later versions used a magnetoresistive sensor for position feedback.
 - On-board microcontroller
 - 1N of force at the actuator arm end
 - 180 degrees of absolute position feedback
 - 140ms to travel 180 deg, stop to stop
 - PID feedback loop with 20kHz PWM motor control
 - Coreless motor and planetary gearbox
 - Total weight: 2 grams
 - Accepts standard RC aircraft servo signals
 - 2.9-4.2V input voltage