Chapter 14: Power Supply and Electrical Issues^317
Diode A diode, despite its two-way sounding name, is a one-way electronic
valve that directs the current to flow in only one direction.
Transistor A transistor, which is the workhorse of a computer, is a
semiconductor capable of storing a single binary value.
Logic gates A logic gate is produced from a combination of a transistor,
resistor, capacitor, and diode. Circuits are made up of logic gates, and circuits
make up electronic systems, like that on the PC’s processor.There really isn’t any reason for you to understand the function of these components
muchdeeperthanthis.Infact,ifyouarereadingthisbookfronttoback,youhavealready
run into these terms in several earlier chapters.Static Electricity and ESD
Static electricity has its good andbad sides inandaround aPC. Unfortunately, you, asthe
user or technician, never really encounter the good side of static electricity, but you
absolutely will or have already experienced the bad side. The bad side of static electricity
(electrostatic charge) on a PC is ESD, or electrostatic discharge.
If you have ever rubbed a balloon or a piece of wool cloth on your hair (something I’m
sure you do everyday), you have experienced an electrostatic charge—it was what made
your hair stand on end. There isn’t much you can do about static electricity; it is a part of
nature and it’s all around you. Static electricity itself is not the problem. The problem
occurs when it comes into contact with a positively charged entity and rapidly dis-
charges. Just like it did on the battery earlier in the chapter, negatively charged particles
(like static electricity) will always flow to a positively charged source (like you when you
touch the door knob). There is a great deal of danger and potential for damage in an ESD.
You know how when you reach for the door knob and, zap! a blue spark jumps from your
finger to the metal? Well, the sna pof the discharge and the tingle in your finger are only
minorevents,butinthatharmlesssparkisthepotentialforalotofdamagetoaPC.Toput
EDS in a kind of perspective for you: lightning is ESD.
YoucanfeelanESDthatcarriesaround3,000volts,butonlyabout30voltsareneeded
to fry circuits and parts on a PC’s motherboard. This means that even if you can’t feel an
ESD, it’s not harmless to an electronic component. ESD is by far the greatest threat for
damage to a PC from its environment.
One way to avoid ESD damage to your PC is to always wear a grounded wrist strap,
like the one shown in Figure 14-3. The wrist stra pshould be connected to either a ground-
ing mat or the PC chassis whenever you are working inside the PC or handling any part
of the computer, except the monitor and power supply. For more information on why
you don’t want to wear a wrist strap when working on a monitor, see Chapter 16.