Practical Applications of Stepper-Motor in Hobby Electronics

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Practical Applications of Stepper-Motor in Hobby
Electronics

• proto-pic.co.uk

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What is a Stepper-motor

• Simply speaking, a stepper-motor is a brushless
  motor running on a DC current, which is able to
  split one full rotation of a gear cog into a
  number of equal steps. These steps do not have to
  be sequential (i.e. in the same direction, rather
  than moving first forward and then backward)
  though in the simplest configuration of the motor
  they often are.

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Stepper-motor with cable

• This is a simple, but powerful stepper motor with
  a 4-wire cable attached.

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How it Works

• The motor is activated using electromagnetic
  coils, which magnetise cogs on the gear wheel. To
  move the cog, the coil currently holding it is
  turned off and a different one is turned on. The
  magnetic pull the stepper-motor exerts on the cog
  teeth thus causes the wheel to change position.
  One such change is referred to as a step.

• The motor is used to make adjustments in
  positioning devices, for example in the laser
  head in a DVD or CD player. The clicking sound
  you sometimes hear in older DVD and CD players is
  an old stepper-motor losing its grip.

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Pros and Cons of using Stepper-motor

• The motor suffers from a lack of torque at higher
  speeds. The faster the wheel turns, the more the
  cog is likely to slip. So applications requiring
  the motor to turn at high speeds may be better
  served using a servo motor instead. The
  resonating effect also exhibited by the
  stepper-motor at high speeds may have an adverse
  effect on device performance.

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• The plus points of the stepper-motor are many.
  For example, its relatively low cost and high
  reliability at low speeds make it ideal for a
  wide range of amateur projects. While its
  simplicity of design means it can operate in even
  quite difficult conditions, where a more
  delicately calibrated motor may have trouble
  functioning properly.
• The motor does suffer from limitations of size,
  in that it gets too big where a large degree of
  steps are required (and hence a large number of
  cog teeth).

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End