In the most generic sense, a “servomechanism” (servo for short) is a device
that uses feedback to achieve the desired result. Feedback control is used
in many different disciplines, controlling parameters such as speed,
position, and temperature.
In the context we are discussing here, we are talking about hobby or radio-
control servo motors. These are small motors primarily used for steering
radio-controlled vehicles. Because the position is easily controllable, they
are also useful for robotics and animatronics. However, they shouldn’t be
confused with other types of servo motors, such as the large ones used in
industrial machinery.
An Assortment of Hobby Servos
RC servos are reasonably standardized - they are all a similar shape, with
mounting flanges at each end, available in graduated sizes. Servos often
come with several wheels or levers, known as “horns”, than can be
attached to the shaft, to fit the device they are operating.
Example Servo Horns
Electrical Connection
Most hobby servos use a standard type of 3-pin plug, with the same control
signaling, which makes RC servos reasonably interchangeable.
The connector is a 3-pin, 0.1" pitch header. One thing that can be confusing
is that the wiring color code isn’t always consistent – there are several color
codes at play. The good news is that the pins are usually in the same order,
just that the colors on them are different.
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