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

–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