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Motors

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Motor Properties

Motors convert electrical energy into rotational movement.
Linear motors also exist. They provide straight line movement. Wikipedia

Conventional Motors have Two Power Connections

Normal motors run at a speed determined by the power supply voltage and the load on the motor. This is fine for devices like cooling fans or motors used to drive vehicles.

These spin in a fairly uncontrolled way.
They are useful for propelling vehicles, powering fans or spinning the washing.
It is possible to measure how fast the motor is spinning but the exact position of the motor is not generally known.
These motors can be any size including huge motors for driving ships or trains.
It's easy to make a big powerful motor
It's easy to make a motor that runs at high speeds
Simple switches or electronics are used for power control
They are efficient - most of the electrical energy is converted into mechanical form
QE2 Engine Room - Big Motors 9 metres across.

Motor Drivers

MOSFET switches are commonly used.
The Back EMF Diode is important.
It protects the MOSFET from high voltages.
It prevents sudden current changes in the motor which would cause the damaging back EMF voltages..