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Controlling A Servo Motor
- May 21, 2018 -

Servomotor takes command from a series of pulses sent from the computer or radio. A pulse is a transition from low voltage to high voltage which stays high for a short time, and then returns to low. In battery devices such as servos, "low" is considered to be ground or 0 volts and "high" is the battery voltage. Servo motors tend to work in a range of 4.5 to 6 volts, so they are extremely hobbyist computer-friendly.


Have you ever picked up one end of a rope that was tied to a tree or held one end of a jump rope while a friend held the other? Imagine that, while holding your end of the rope, you moved your arm up and down. The rope would make a big hump that would travel from your end to the other. What you have done is applied a pulse, and it traveled down the rope as a wave. As you raise your hand up and down, if you keep your hand in the air longer, someone watching this experiment from the side would see that the pulse in the rope would be longer or wider. If you bring your hand down sooner, the pulse is shorter or more narrow. This is the pulse width. If you keep your end going up and down, making a whole bunch of these pulses one after another, you have created a pulse train (see Figure 6 below). How often did you raise and lower your end? This is the frequency of your pulse train and is measured in pulses per second, or Hz (abbreviation of "hertz").