Actuators

Motors can also be controlled on the AVR. There are some extra parts involved. Foremost of course is a DC motor. It also needs a motor controller, which supplies the needed voltage and current to the motor, including the direction of current. The direction of current through the motor determines the rotational direction of the motor: clockwise or counter clockwise.

Pulse Width Modulation (PWM) is a technique that we use to control the speed of the motor. A DC motor's speed is determined by now much current is flowing through it. Intuitively, if we supply a low DC current, the motor will spin slowly. It will spin more quickly with a higher current. As it turns out, it is difficult to create a circuit that supplies a varying current like this. So, we use PWM. Pulse Width Modulation used two discrete values of current (none and full) in pulses that average to the desired current value you need to make the motor act as you want. The longer the pulse, more average current flows through the motor, and the faster it goes. We speak of the length of the pulse in terms of something called the Duty Cycle.

PWM can be used to control the apparent output intensity of LED's, too!

explain opposites attract for magnets and electromagnets

Acoustic System Actuators

Lorentz Force Actuator

e.g. woofers and shakers

Reluctance Force Actuator

e.g E-Bow, Sustainiac