EMAX ES08MD II 12g Digital Metal Gear Servo

EMAX ES08MD II 12g Digital Metal Gear Servo

The EMAX ES08MD II digital servo is a high-quality servo that is ideal for RC helicopter tails. The listing says it has plenty of torque and ample speed, which makes it the perfect budget everyday servo.

It is supplied with mounting hardware and additional servo output arms, so it is ready to install on a model.

The specification list gives an operating voltage of 4.8 to 6.0V, a torque of 1.6 to 2.0 kgf and a speed of 0.12 to 0.10 seconds per 60 degrees, and identifies the servo type as digital.

Key features

• High-quality material: built for regular use.

• Made for RC helicopter tails: fast, precise tail control.

• Plenty of torque: 1.6 to 2.0kgf.

• Excellent speed: 0.12 to 0.10 seconds per 60 degrees.

• Digital servo: quick response and good holding power.

• Complete kit: mounting hardware and extra output arms.

How a digital servo works

A hobby servo combines a small motor, a gearbox and a position sensor with control electronics. You send it a pulse every 20 milliseconds or so, and the width of the pulse tells it where to go: about 1.5 milliseconds is centre, with roughly 1.0 and 2.0 milliseconds at the ends. The servo drives its output shaft until the sensor says it has reached the commanded position, then holds it against the load.

Digital servos process the signal with a microcontroller and drive the motor at a much higher rate than analogue servos, which gives faster response, a smaller dead band and stronger holding torque. Metal gears cope better with shock loads than plastic ones, and ball bearings keep the shaft smooth and reduce wear.

Always power a servo from a supply that can deliver its peak current, not from a weak receiver port, and keep the linkage free so the servo never strains against a mechanical stop. A stalled servo draws a large current and can overheat within seconds.