Download Electrical Manual

Basic Circuit
A basic circuit has a power supply like a battery, some type of resistance such as a light bulb and usually a
switch to complete the circuit. If you are using a flashlight, it has batteries a light bulb and is off until you
complete the circuit when you use your thumb to switch the flashlight on. The circuit is completed using
conductors. These conductors are things like copper, iron, gold, platinum, silver, aluminum, led and other
metals.
Volts, Amps, and Resistance
Using volts, amps, and
resistance is a way of
explaining electricity. It all
starts with atoms and electrons
that we can’t see. Let’s just
pretend that we can see them
and atoms are houses. Each
house can only have two
people (Electrons) in them at a
time (IT IS THE LAW!) and all
the houses (Atoms) have two
people (Electrons) in them
already, ah life is perfect. Now
a new person (an electron)
comes to the city and he goes
to the first house, the law says that only two people can be in each house (Atom) and he kicks-out one of the
people (electron) and he has to go to the next house (Atom) and he kicks-out another person (electron) that
goes to the next house (Atom) and so on and so forth to complete the circuit. It is those excited electrons
(people) that make electricity. Those electrons keep jumping from one atom to another because there are only
so many electrons allowed in each atom.
Explaining Volts, Amps and Resistance using water
1
Voltage is electrical pressure. We can see
voltage as water pressure. The less pressure the
slower the water comes out of the hose. If there
were a lot of pressure the water would be coming
out of the water hoes like a fire hose.
Amps or current are the flow of water. The total
flow of water that is produced by the pressure is
the amps. It is the amount of water that is flowing
over time. If there are buckets being filled with
water at high amps the buckets will be filled faster
with high amps than low amps. This is seen as
the current of the circuit.
Resistance is the restriction of the water. It can
be seen as the size of the hose diameter. The
larger the hose diameter the more water that goes
through (Less Resistance) and the smaller the
hose (More Resistance) the less the water that
can flow through the hose.
2
Ohm’s Law
Volts = Amps x Resistance
Ohm’s Law can explain electricity using math. All appliances even an I-POD was developed using he formula
of Ohm’s Law. Ohm’s Law tells the pressure, flow or resistance of a circuit.
Volts = V
Amps = I
Resistance = R
Since there are only three factors in the equation, the equation can be seen as:
(1) V = I x R
(2) I = V/R
(3) R = V/I
The triangle can be used to know which formula to use. If
volts is the unknown then by looking at the triangle the
resistance and the amps are underneath or at the bottom
of the triangle which means to multiply the resistance and
the amps. If the resistance is unknown, by looking at the
triangle the volts are on top and the amps are underneath.
This means to divide the volts by the amps ( V/I ). If the
Amps are unknown, look at the triangle and by seeing the
volts are above the resistance and divide the volts by the
resistance ( V/R ).
V
VOLTS
R
RESISTANCE
3
I
AMPS
Series Circuit
A series circuit is a circuit that is one wire making a circle. Voltage changes at each resistor and get a total
voltage. Series circuits change the pressure of the current.
Ohm’s Law at work
Volts total = ?
Resistance = 1 ohm R1 + 1 ohm R2 + 1 ohm R3 + 1 ohm R4 = 4
ohms
R total = 4 ohms
Amps = 3
At resistor 1 the voltage would be:
V at R1 = 3 amps x 1 ohm
V at R1 = 3 volts
At resistor 2 the voltage would be:
V at R2 = 3 amps x 1 ohm
V at R2 = 3 volts
At resistor 3 the voltage would be:
V at R3 = 3 amps x 1 ohm
V at R3 = 3 volts
At resistor 4 the voltage would be:
V at R4 = 3 amps x 1 ohm
V at R4 = 3 volts
Total Voltage can be added from the voltage at each resistor or could be derived by using Ohm’s Law:
Voltage Total = Resistance Total x Amps
Voltage Total = 4 ohms x 3 amps
Voltage Total = 12 volts
4
Parallel Circuits
A parallel circuit is a circuit that changes the amount of amps used but does not change the volts or pressure of
the circuit. Lights in a home are run on parallel circuits. If all the lights are on in a home all the lights are bright,
even if lights are added the lights all stay at the same brightness. If a home’s lights were wired in a series
circuit each light that was to be turned on each light would dim the other lights.
Amps = ?
Voltage total = 12 volts
R1 = 1 ohm
R2 = 2 ohm
R3 = 3 ohm
Amps at resister 1
I = V/R
I = 12/1
I = 12 amps
Amps at resister 2
I = V/R
I = 12/2
I = 6 amps
Amps at resister 3
I = V/R
I = 12/3
I = 4 amps
BATTERY
12 VOLTS
Total amps are derived by adding the amps from each resister:
Amps total = 12 amps + 6 amps + 4 amps
Amps total = 22 amps
5
Resistors
Ω
Resistors are used to control the amount of electrical power
going through a circuit. Power is measured in
Calories or heat that is produced. Resistance makes heat. If
using a small diameter extension cord for a high amp table
saw, the wire will get hot because of the resistance caused by
the small wire and all the electricity trying to get through the
wire. Resistors work in the same way. They use up electricity
and some do get hot. Resistors are used to change amps or
voltage running through a circuit.
The value of resistors can be calculated by the colored bands
that are around the resistor.
RESISTER
CODE
COLOR
BLACK
BROWN
RED
ORANGE
YELLOW
GREEN
BLUE
VIOLET
GRAY
WHITE
1ST
BAND
2ND BAND 3RD BAND
0
1
2
3
4
5
6
7
8
9
0 0 ZEROS
1 1 ZEROS
2 2 ZEROS
3 3 ZEROS
4 4 ZEROS
5 5 ZEROS
6 6 ZEROS
7 7 ZEROS
8 8 ZEROS
9 9 ZEROS
Diodes
Diodes control which way the current flows through a circuit. Diodes only let the current flow in one direction.
Capacitors
Capacitors are used to store electricity energy. They are like batteries except that they discharge all the energy
at one time and completely. Think of a capacitor as a water balloon that is being filled up. If the balloon keeps
being filled to the point where it breaks and the water is released. A capacitor gets to its breaking point and
releases the energy. But unlike a balloon the capacitor can be filled with electricity again and again. Capacitors
are measured in Farads. Almost all capacitors are micro farad capacitors, micro meaning 1 one-thousand of a
6
farad. Capacitors are used to smooth out DC currents or for storing energy. Energy can be stored until the
energy is released. People can be hurt by a capacitor that is full of energy, SO NEVER TOUCH THE LEADS
OF A CAPACITOR THAT HAS NOT BEEN DISCHAGED OR AN ELECTRICAL SHOCK CAN OCCURE!
Transistors
Transistors switch an electrical current on and off. They are switched on and off by the amount of voltage going
though the circuit. There are two types of transistors. The first is used for letting electricity go in the positive
current direction they are called NPN transistor. The other transistor is used for negative voltage and is called a
PNP. Transistors have three parts, these are: 1) a collector, 2) base, and 3) an emitter.
Integrated Circuits
Integrated circuits are computer chips with as little as three legs and as many as can be imagined. Most have
eight to twenty legs. Integrated circuits can have resistors, capacitors, diodes and transistors all in one tiny
package. Even though two integrated circuits look the same they are completely different.
7
LED Lights
LED light are used to show when a circuit is on or used in TV remote to signal the TV. LED can be in visible
light or infrared. These LED have a side that is flat and when installing an LED the leads must be in the correct
position or the LED will not work.
Photo Censers
Photo censers are used switch on and off when exposed to light. Some photo censers control the amount of
electricity flowing through a circuit by how much light is seen by the photo censer.
8
Alternating and Direct Current
Alternating Current or AC
Alternating Current or AC is the type of electricity that homes use. Your computer is plugged into the wall that
supplies the computer with electricity. The electricity is produced by large generators. These generators
change the flow of electricity. This means that the electricity moves in both directions, becoming positive and
then negative and then back again. The switching back and forth of electricity is called Alternating Current.
This type of electricity is under a lot of pressure (volts), so this type of current can hurt of kill if not used
properly.
Direct Current
Direct Current or DC does not alternate current. This type of current flows in one direction like a garden hose.
The water goes in one end and out the other. Batteries use direct current. Once the flashlight is switched on,
completing the circuit the electricity flows from the positive side of the battery to the light bulb and back to the
negative side of the battery. The electricity goes in one direction only.
9
Soldering Guide
Safety Precautions
• Never touch the element or tip of the soldering iron.
They are very hot (about 400°C) and will give you a nasty burn.
• Take great care to avoid touching the mains flex with the tip of the iron.
The iron should have a heatproof flex for extra protection. Ordinary plastic flex melts immediately if touched by
a hot iron and there is a risk of burns and electric shock.
• Always return the soldering iron to its stand when not in use.
Never put it down on your workbench, even for a moment!
• Allow joints a minute or so to cool down before you touch them.
• Work in a well-ventilated area.
The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping
you head to the side of, not above, your work.
• Wash your hands after using solder.
Solder contains lead.
Preparing the soldering iron
• Place the soldering iron in its stand and plug in.
The iron will take a few minutes to reach its operating temperature of about 400°C.
• Dampen the sponge in the stand.
The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to
remove excess water. It should be damp, not dripping wet.
• Wait a few minutes for the soldering iron to warm up.
You can check if it is ready by trying to melt a little solder on the tip.
• Wipe the tip of the iron on the damp sponge.
This will clean the tip.
• Melt a little solder on the tip of the iron.
This is called 'tinning' and it will help the heat to flow from the iron’s tip to the joint. It only
needs to be done when you plug in the iron, and occasionally while soldering if you need to
wipe the tip clean on the sponge.
• You are now ready to start soldering!
Please turn the page for further instructions...
10
THE
ELECTRONICS
Making soldered joints
• Hold the soldering iron like a pen, near
the base of the handle.
Imagine you are going to write your name!
Remember to never touch the hot element or
tip.
• Touch the soldering iron onto the joint to
be made.
Make sure it touches both the component
lead and the track.
Hold the tip there for a few seconds and...
• Feed a little solder onto the joint.
It should flow smoothly onto the lead and
track to form a volcano shape as shown in
the diagram below. Make sure you apply the
solder to the joint, not the iron.
• Remove the solder, then the iron, while keeping the joint still.
Allow the joint a few seconds to cool before you move the circuit board.
• Inspect the joint closely.
It should look shiny and have a ‘volcano’ shape. If not, you will need to reheat it and feed in
a little more solder. This time ensure that both the lead and track are heated fully before
applying solder.
THE
ELECTRONICS
What is solder?
Solder is an alloy (mixture) of tin and lead, typically 60% tin and 40% lead. It melts at a temperature
of about 200°C. Solder for electronics use contains tiny cores of flux, like the wires inside a mains flex. The flux
is
corrosive, like an acid, and it cleans the metal surfaces as the solder melts. Without flux most joints would not
stat soldered for long.
11
Common electronic part symbols:
Battery
Diode
Capacitor
NPN type Transistor
PNP type Transistor
LED Light
12
Resister
Light sensitive Resistor or
Photo-sensor
Lamp
Reference
Some pictures such as circuit pars and the soldering picture used in this book are from
Electronics Club. The Electronics Club gave permission to use any pictures or text.
http://www.kpsec.freeuk.com/index.htm
Stephen R. Matt, Basic Electronics and Electricity
(Goodheart-Willcox Co; 6r.e. edition (July 1, 1998)
13