• Logic-level outputs can’t drive a motor directly.

• Solution: Relays– Relays allow one circuit to

switch a second circuit– isolates circuit from potentially

dangerous voltages

• Main types of relays– Reed Relay– General Purpose Relay– Solid State Relay– Transistor

• Advantages• little power to energize• Quiet

• Disadvantages• Can’t control large loads• Contacts can weld

together

• Advantages• Can handle very large loads• Control multiple contacts

• Disadvantages• Physically large• Mechanical failure

• Advantages• Fast switching• Silent

• Disadvantages• Higher cost• Heat production

• Advantages• Fast switching• Silent• Low power/current

• Disadvantages• DC only• Small currents

Lead Screw

Pneumatic

Mechanical

• Mechanical– Converts rotary motion of a knob or handle into linear

displacement via screw or gears • Pneumatic / Hydraulic

– Compressed air moves a piston inside the cylinder which moves the actuator directly.

• Lead Screw– Converts rotary motion via motor into linear

displacement. A lead screw with helical threads machined on its circumference rotates, while a nut with corresponding helical threads moves the actuator linearly.

- Uses electrical energy to produce mechanical work- Commonly used in refrigerators, washing machines, fans, pumps, and computer equipment

Advantages

- No fossil fuels

- Noise reduction

- Wide range of sizes

- Fewer components

Disadvantages

- Less powerful

- Battery limitations

Types

AC Induction

AC Synchronous

Stepper DC

Brush DC

Brushless DC

- Transforms mechanical energy into electrical energy

- Sources of mechanical energy include- Combustion Engines

- Compressed Gas

- Steam/Gas Turbines

- Solar and Wind