# CP1610: Introduction to Computer Components Computer Power Supplies.

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CP1610: Introduction to Computer Components Computer Power Supplies

Purpose of a Power Supply Connect PC to wall outlet. Distribute the right amount of power to all parts. Transformer. Rectifier.

What is a Transformer? PC power supplies ‘transform’ electrical voltage from the building’s power supply. Reduces voltage from 120V or 240V down to 12V, 5V, or 3V (as needed by the PC). Distributes the right voltage to each PC part.

What is a Rectifier? Wall outlets provide Alternating Current (AC). Computer needs Direct Current (DC). Power supply converts electricity from AC to DC.

Power Regulation Computers need stable, well-regulated power supplies. Fluctuations or interruptions can:  Damage parts;  Cause loss of data;  Create electromagnetic interference (EMI);

Protecting Power Supplies SPS  Stand-by Power Supply UPS  Uninterruptable Power Supply

SPS vs. UPS SPS  Stand-by Power Supply;  Acts like a backup battery in case of power failure; UPS  Uninterruptable Power Supply;  Computer is constantly powered by the battery;  Also regulates voltage;  Reduces EMI;

Electricity Basics Three fundamental properties:  Potential difference across the circuit (Voltage)  Current, or flow of electricity (Ampere or Amp)  Resistance on the circuit (Ohm)

Ohm’s Law Formula to calculate voltage, current, or resistance. V = I x R Symbols:  V = Voltage  I = Current  R = Resistance

Calculating with Ohm’s Law Voltage:  V = I x R Current:  I = V / R Resistance:  R = V / I Symbols:  V = Voltage  I = Current  R = Resistance

Electrical Power Measured in Watts (W) Multiply Voltage by Current W = V x I

Alternating vs. Direct Current AC cycles back and forth. DC travels in only one direction. AC is more economical on a large scale. Computers require DC to operate.

Short Circuits Occur when electricity crosses paths or circuits. Can be dangerous. Can damage equipment. Prevented by using fuses.

Electrical Safety Before you open the case:  Turn off the computer;  Unplug the computer; After you open the case:  Use a static strap and rubber mat;  Never use magnetized tools;  Don’t touch parts with a graphite pencil;  Don’t stack parts on top of each other;  Don’t touch parts with your hands or fingers!

Working with Monitors; DON’T! Monitors use very high voltage. Retain a charge, even when turned off. The high voltage can KILL! Let a qualified technician do the work. Do not throw monitors in the garbage.

Overheating Computers overheat above 180 o F. Use fans to cool:  Power supply;  CPU;  Interior of case; Never leave your case open. You can also use liquid cooling.

Power Management Conserve electricity Protect environment Save money Can control power to:  Main system;  Monitor;  Hard drives;  Printers;  Other components;

Power Management Settings Doze Time  Reduces 80% of power consumption; Standby Time  Reduces 92% of power consumption; Suspend Time  Reduces 99% of power consumption; Hard Drive Standby Time  Shuts down the hard drive;

Energy Star Ratings Devices that comply with environmental protection standards. Can apply to:  Computers;  Monitors  Printers;  Fax Machines;  Other Devices;