Automotive Electronic

AUTOMOTRIZ ELECTRONICOS

1 Chonan Technical Service Training Center

AUTOMOTRIZ

ELECTRONICOS

Published by

Chonan Technical Service Training Center



FOREWORD

This service-training booklet has been prepared for service technicians of

authorized distributor to familiarize them with vehicle basic electronic. It is our

intention to increase the level of skill and knowledge of service personnel to

enable effective and efficient problem diagnosis and repair.

December. 2003 Printed in Korea

Published by Chonan Technical Service Training Center

copyright by Hyundai Motors

All right reserved.

Chonan Technical Service Training Center

http://training.hmc.co.kr

[email protected]



CONTENTS

1. General ·········································· 7 8. Thermistor ··································· 45

2. Compositions/essence of electricity ·· 8 8.1 NTC type ··········································· 45

3. Conductor & nonconductor ·············· 9 8.2 PTC type ············································ 46

4. Semiconductors ······························ 11 9. Photoconductive cell ························· 47

4.2 Semiconductor material ························· 12 10. Piezo-electric element ···················· 48

4.3 Classification of semiconductor ·············· 13 11. Hall effect ··········································· 49

5. Diode ······················································· 17 12. Integrated circuit ······························ 51

5.1 Diode general ······································· 17 12.1 Integrated circuit general ··················· 51

5.2 Diode usage & symbol representation ····· 17 12.2 Analog I.C ································· 52

5.3 Diode operation ····································· 18 12.3 Digital I.C ········································· 53

5.4.Characteristic of diode ··························· 20 12.4 Various logic circuits ························· 54

5.5 Rectification operation of diode ············ 21 13. Microcomputer ·································· 59

5.6 Example of diode use in automobile ······· 23 14. To understand electronic circuit ····· 63

5.7 Diode check method by using a m-meter 25 APPENDOX ············································ 67

6. Special type of semiconductor diode · 26

6.1 Zener diode ·········································· 26

6.2 Photo diode ··································· 28

6.3 LED (Light emitting diode) ······················ 29

7. Transistor ··············································· 31

7.1 What’s transistor? ···························· 31

7.2 Basic operation of transistor ··················· 32

7.3 Judgment of good/bad transistor ········· 42



1. General

Today in automobile there are essentially used application fields of electricity and electronic beginning

from switch for simple on /off of lamp to many equipments of engine management system (EMS) ,

antilock brake system (ABS) , transmission control system (TCS) , airbag, instrumentation system,

body electrical system (BCM), etc . requiring microcomputer control .

Because of use of so many sophisticated electrical equipments and electronic parts, there come forth

also many electronic defects in comparison to traditional mechanical defects as for car trouble causes.

Accordingly learning the basic knowledge of electricity and electronic seems exigent subject for

automobile maintenance and service.

.

Here it is hoped to become opportunity to understand basic principle and to learn how they apply in

automobile, apart from the complicated structure or any academic theoretic.

And it is hoped to be a little help in more efficient maintenance and trouble repair..



2. Compositions and essence of electricity

Every material is composed of molecules each of which is in turn chemically composed of aggregates

of atoms.

Example: water molecule (H2O) = two hydrogen atoms (H2) + one oxygen atom (O)

As the above figure, electrons are quickly turning around nucleus in conformity with respective

orbits as the earth and planets are turning around sun .

Only a certain number of electrons can exist in each electron orbit (K: 2, L: 8, M: 18, . . . ) while

each element has its characteristic number of electrons (e .g . hydrogen 1, carbon 6, oxygen

8, . . . ).

Generally nucleus has positive electricity (+) and electron has negative electricity (-) while these

two have mutually attractive character so that atom becomes electrically neutral (positive electricity

quantity = negative electricity quantity). Because attractive force from atomic nucleus to electrons

of outermost orbit (valence electrons) is the weakest , these electrons are easy to escape from orbit

due to external stimulus (heat , electricity, light , . . .) and may move to other orbit , These electrons

got out of orbit are called free electrons which are essence of electricity. Movement of these free

electrons directly becomes electric current . Namely, it means that movement of these free

electron started signifies that electric current flows,

Atom relationship model

Electron

Proton

Neutron Atomic

nucleus

K Orbit

L Orbit

M Orbit



3. Conductor & nonconductor

If materials are electrically classified, they may be divided into conductor which transmit electricity

well, nonconductor which do not transmit electricity and semiconductors in middle between the two

while these characteristics are determined by electronic configuration according to atomic structure of

material .

1) Conductor : where electricity flows well

Here fall most metals where free electrons may well move in the interior of material . Order of

good conductance of electricity : silver copper gold aluminium tungsten zinc

nickel ....

2) Nonconductor : where electricity does not flow well

It is called insulator where free electron is not easily generated e .g . ceramics, glass, rubber,

plastics, wood etc .

3) Semiconductor : which has medial characteristics between conductor and nonconductor

Here fall silicon (Si), germanium (Ge), selenium (Se) etc . which are used as raw material of

electronic part.

As for automobile wiring, multistrand type is contained inside a clothing of cord where copper

(alloy) is mainly used as stuff material . Cord thickness is determined by electric current value,

load, continuity, temperature etc . The larger the electric current , the longer the cord and the

longer the electric current flow time, the thicker the electric cord shall be .

General Specification Table

Area

(mm )

Strand

Diameter

No. of

Strands

Electric

Wire OD

Allowable

Current

(A)

0.5 0.32 7 2.2 9

0.85 0.32 11 2.4 12

1.25 0.32 16 2.7 15

2 0.32 26 3.1 20

3 0.32 41 3.8 27

5 0.32 65 4.6 37

8 0.45 50 5.5 47

15 0.45 84 7.0 59

20 0.8 41 8.2 84

0.32 mm

2.2 mm

0.5 sq (Allowable

electric current =

9 A)



MEMO



4. Semiconductor

4.1 What is semiconductor?

In material, there are conductors easy for electric current to flow and nonconductor difficult for

current to flow by the electronic property. Semiconductor denotes material of medial property

between conductor and insulator. Namely, here electric current is neither easy to flow as in

conductor nor difficult as in nonconductor. Semiconductor is material that has such peculiar

electric property. So semiconductor is material that has medial type character between conductor

and nonconductor.



4.2 Semiconductor material

The specific resistance of copper used as electric conductor is 10-6 Ωcm that is lowest and even the

specific resistance of Ni-Cr used as electric resistance wire is 10-4 Ωcm while these materials are

called conductors because they conducts electricity well . If specific resistance is more than 1010

Ωcm then little electricity is conducted there so that such material is used as insulator. Meanwhile

material in between such conductor and insulator, not belonging to conductor and nonconductor,

are called semiconductor where belong germanium and silicon used in manufacturing the diode

and transistor.

State Specific Resistance Material

10-6 Silver, copper

Platinum

10-4 Nichrome

Carbon electrode

10-2

Pyrite

1

Germanium

102

Silicon

104

106 Copper dioxide

108

1010 Bakelite

1012

1013 Mica, diamond

1014

1015 Glass

1016

1018 Quartz glass

Conductor

Semiconductor



Semiconductors play role of conductor or nonconductor according to specific condition (relationship

between voltage, electric current , temperature etc . ). The main elements that are most frequently

used are silicon (Si) and germanium (Ge) while such conductor of high purity is called as intrinsic

semiconductor. Silicon and germanium respectively have four electrons on outermost orbit .

Namely in their respective crystal structures, the form becomes that each atom shares its own four

electrons with its partner atom. Because of such covalent bond, the material becomes an electric

insulator and has little electrical utilization value so that it cannot independently be used as

semiconductor. Therefore it is used as a form of impurity semiconductor by adding small

proportional quantity of other element atoms to these intrinsic atoms of valence 4.

4.3 Classification of semiconductor

Semiconductor is largely constituted of two forms.

Here are iintrinsic semiconductor that does not utterly contain impurity in material crystal and

impurity semiconductor that is added of specific impurity material into intrinsic semiconductor in

order to improve conductivity.

Generally diode and transistor belong to this impurity semiconductor.

And this impurity semiconductor is also classified into two according to role of added impurity

material .

Roles of impurity material are to increase in semiconductor the number of

- Increase free electron of semiconductor inside

- Increase hole of semiconductor inside

Therefore among impurity semiconductors, that added of impurity to increase the number of free

electron are called negative type semiconductor while that added of impurity to increase the number

of hole are called positive type semiconductor.

S

i

S

i

S

i

S

i

S

i

Outer block Orbit

<Silicon covalent bond>

Si

<Silicon atomic structure>



4.3.1 Intrinsic Semiconductor

▷ This is intrinsic semiconductor containing no impurity material at all in its crystal structure .

▷ Purity of intrinsic semiconductor has been refined about 99.999999999 % (over ten-nine) with 11

nine.

▷ For example germanium and silicon belong to this kind .

4.3.2 Impurity semiconductor

▷ This is impurity semiconductor added of specific impurity material into intrinsic semiconductor to

improve conductivity.

▷ General semiconductors of diode or transistor belong to this impurity semiconductor.

▷ Classification of impurity semiconductor

a. N type semiconductor is that added of impurity to increase number of free electron in

semiconductor.

b . P type semiconductor is that added of impurity to increase number of hole in semiconductor.

1) P Type Semiconductor

This is made by adding the material (Ga : gallium ; In : gallium ; B : boron) having three valence

electron in intrinsic semiconductor. Though silicon has four outer layer electron, if these two kinds

of material meet each other, then silicon atom from these two kind of atoms cannot share one

electron so that electric current can flow easier while this vacancy in octet is called hole. And it is

called P (positive) type semiconductor because it assumes positive (+) electricity by electron

deficiency. When voltage is applied, electron fills the hole site so that the hole continuously moves

down, electric current is said to flow by means of hole in P type semiconductor.

Structure of “P” type semiconductor

Hole



2) N Type semiconductor

This is made by adding the material (P : phosphorus ; As : arsenic ; Sb : antimony) having five

outermost layer electron in intrinsic semiconductor. If element of valence 5 is added to bind with

silicon then one electron remains as surplus in octet so that electric conduction may be accomplished

easier by means of free activity of this remainder electron.

And it is called N (negative) type semiconductor because it assumes negative (-) electricity.

Electric current flows by means of electron in N type semiconductor (carrier : electron) .

3) P-N Junction

If P type semiconductor and N type semiconductor are chemically bonded with each other, there is

made portion where carrier does not exist as hole and free electron are bonded together at narrow

part of junction surface. This junction surface is called depletion layer while semiconductor bonded

thus is called PN junction semiconductor or diode. Accordingly there exists electric charge of

different polarity from each other on either side of depletion layer and there is generated a little

amount of electric potential difference which is called electric potential barrier.

P N

Depletion layer Hole

Electron

Superfluity electron

Structure of “N” type semiconductor



MEMO



5 Diode (Diode for rectifier circuit)

5.1 Diode general

Diode is semiconductor part substance flowing the electric current always in only one direction . As

to say, semiconductor is called as such because it has intrinsically this kind of property. Although

transistor is also a kind of semiconductor, diode specifically purports thus that electric current shall

flow always in only one direction . Silicon is most frequently used as semiconductor material

whereas besides there are used also germanium and selenium for this purpose

5.2 Diode usages and symbol representation

Main function of diode is to rectify electric current to flow it always in only one direction. But it is

also used in many other functions so that main functions may be summarized as follows : -

- Usage as electric current rectifier to change the alternating current to the direct current in

electric supply facilities

- Use as detector to take out signal from radio frequency

- Usage in switching to control electric current ON/OFF

- Prevention of backward current flow

- Usage in protective circuit

Besides it is used in variety of wide range according to diode sort and usage.

Anode Cathode

Diode symbol Diode Polarity

Anode(－) Cathode(＋)



5.3 Diode operation

§ Forward diode for forward bias

§ Forward diode for backward bias

5.2.1 Forward diode for forward bias

Diode has form to have connected terminals on both sides of P-N junction semiconductor to have

characteristics to flow electric current always in only one direction .

In forward direction as in figure if positive (+) voltage is applied at P type semiconductor and

negative (-) voltage is applied at N type semiconductor, hole and electron repulse to electric source

so that electric potential barrier is lowered and also depletion layer is narrowed. Consequently

hole and electron may move to each other across junction surface. Accordingly electric current

flows by movement of hole and electron .

Forward direction circuit of diode

Lamp turns on because diode has been connected in forward direction in circuit below.

Battery

Anode(＋) Cathode(－)

Lamp ON

<Occasion that supply forward voltage / Electric current is flowing>

P N

Depletion layer

Current flow



5.2.2 Backward diode for reverse bias

This time let us in reverse direction apply negative (-) voltage at P type semiconductor and positive (+)

voltage at N type semiconductor. Then hole of P type semiconductor is attracted to negative (-) side

of electric supply while electron of N type semiconductor is attracted to positive (+) side of electric

supply. Consequently electric potential barrier is heightened and accordingly depletion layer is also

widened so that electron movement cannot arise between the two kinds of semiconductor.

As the result , electric current does not flow

Backward direction circuit of diode

Lamp turns off because diode has been connected in backward direction in circuit below.

Battery

Cathode(－) Anode(＋)

Lamp Off

< Occasion that supply backward voltage / Electric current is not flowing >

No current flow

P N

Depletion layer



5.4 Characteristic of diode

It can be seen that , when forward voltage is gradually increased from 0 V, electric current abruptly

flows if a certain voltage is reached. Namely electric current only becomes to flow if voltage is

applied over about 0.6~0.7 V (Ge diode: 0.3~0.4 V). And if backward voltage is applied, electric

current does not flow up to some voltage but abruptly flows at voltage over some definite value.

Voltage at this instant is called breakdown voltage.

Namely diode is broken down if it is connected in reverse direction and voltage above breakdown

voltage is applied.

Voltage-Current characteristicsGraph of Forward Voltage-Current Characteristics Diode: Diode

Current Flow to Applied Voltage

When forward bias voltage is applied below 0.7 V → micro current flows : diode does not operate

When forward bias of threshold voltage of 0.7 V is applied → diode operation current flows : diode

operates

Forward direction voltage characteristic of silicon junction diode

ID(mA)

VD(Volt)

Silicon: 0.6~0.7 volt

Forward direction

Backward direction

Breakdown voltage

Characteristic curb of diode

•60 •40 •20

•I [mA]

•0.2 •0.4 •0.6 •0.8 •1.0 • Volt

Diode forward direction

Spiritual enlightenment point



5.5 Rectification operating of diode

An alternating current signal may be rectified to a direct current by using characteristic of electric

current in diode to flow always in only one direction. Rectifier circuit may largely be classified into

half wave rectifier circuit and full wave rectifier circuit .

5.5. 1 Half -wave rectifier circuit

When applying an alternating current to the circuit , at moment when positive (+) side signal comes

in, electric current flows in forward direction, but at moment when negative (-) side signal comes in,

electric current does not flow because it becomes the reverse direction. This kind of circuit to flow

electric current for only one side is called half wave rectifier circuit .

Time

Time Volt

Volt

Input voltage

Output voltage

A.C

D.C

Diode

Input

Voltage A.C VR = D.C R

IR

Output

Voltage

Half -wave rectifier



5.5.2 Full-wave rectifier circuit

Next for other device also when applying an alternating current to the circuit , electric current flows

through D1 and D4 during moment of positive (+) half cycle period of alternating current signal while

the current flows through D2 and D3 during moment of negative (-) half period. This kind of circuit to

flow electric current for both of half periods is called full wave rectifier circuit . ( *Although particularly

here is represented a full wave rectifier using a bridge, there are also full wave rectifier circuit using

the center tap of transformer, voltage doubler rectifier circuit etc . )

Time

Time

Volt

Volt

Input

Voltage

Output

Voltage

R

V =

D.C

V =

A.C

D1 D2

D3 D4

Bridge circuit full-wave rectifier



5.6 Example of diode use in automobile

Alternator rectifier

AC voltage generated at stator coil is transformed to DC voltage across the diode

Voltage of A: DC 13.7 volts

Voltage of B: AC Pick-to-Pick voltage 13.7 volts × 2 = 27.4 volts

AC voltage of Pick-to-Pick voltage of B is outputted only in + voltage after passing the diode so that

only 1/2 voltage of 27.4 V is outputted.

Namely AC voltage after passing the forward diode is outputted in accordance with vanishing of –

voltage.

B

A

Alternator internal circuit

To Battery From fusible link From charging lamp



Diode installed in relay to prevent surge voltage

1) If power transistor of controller turns on, then the relay turns on .

2) Motor operates as the relay turns on .

3) When power transistor turns off in controller, a high surge voltage about 80volts

is instantaneously generated between A and B according to Lenz law so that it becomes

+ voltage.

4) If this surge voltage of 80 volts flows in the controller, the controller may be damaged .

5) In order to prevent this problem , diode is installed in the relay so that the surge voltage

generated between A~B shall digress in direction from A to C across diode to be

extinguished for controller damage prevention .

Diode connection in forward direction and reverse direction in electric circuit

Forward bias direction connection

Backward bias direction connection

M

Relay

Controller

ㄱ

Motor

Battery

A

A

B

C

Battery

Anode(＋) Cathode(－)

Lamp ON

Battery


Lamp Off



5.7 Diode check method by using a multi-meter

If we had understood that diode is PN junction semiconductor where electric current would flow in

case of forward direction but would not flow in case of backward direction, we can judge it whether

good or bad in accordance with the following.

5.7.1 How to check by using a Digital Multi-Meter

1) Select resistance or diode mode for the select switch of digital meter.

2) It is normal if resistance value is small when red lead wire has been connected to diode anode

(+) and black lead has been connected to cathode (-).

3) And it will be rather good if resistance value is higher when connected inversely.

① Short condition : normal if value is near 0 ohm when measuring in forward direction and

backward direction .

② Open condition : normal if value is near infinity ohm when measuring in forward direction

and backward direction .

When checking by using digital multi meter = Normal condition

5.7.2 How to check by using an Analog Multi-Meter

1) Select at resistance range × 100 for the select switch of analog multi meter.

2) It is normal if resistance value is small when black lead wire has been connected to diode

anode (+) and red lead has been connected to cathode (-).

3) And it will be rather good if resistance value is higher when connected inversely.

① Short condition : normal if value is near 0 ohm when measuring in forward direction and

backward direction .

+ - - +

Resistance : ∞ Ω Resistance : ≒ 0 Ω

+ －

Red

lead

wire

Black

lead

wire

Red

lead

wire

Black

lead

wire

0 Ω ∞ Ω

Anode Cathode Anode Cathode



② Open condition : normal if value is near infinity ohm when measuring in forward direction

and backward direction .

When checking by using analog multi meter = Normal condition

6. Special type of semiconductor diode

Diodes are used for a number of purposes.

Voltage rectification, voltage regulation, and even light production are some of their various uses.

Following is a brief description of some diode type you might encounter.

6.1 Zener diode

1) Zener diode symbol

2) Zener diode characteristic

When the diode is forward biased, it acts like reverse diode or a closed switch.

However, the zener diode has unique reverse bias qualities that make differ from the typical

diode.

The zener diode goes in to reverse bias at various voltages. The amount of voltage required for

reverse bias varies according to the zener diode selected.

Some typical reverse bias voltages are 2.4V, 5.1V, 6.0V, 9.1V, 12.0V, ect.

At this point, when the applied voltage increased, the forward current increase.


Resistance : ≒ 0 Ω Resistance : ∞ Ω

- +

Black

lead

wire

Red

lead

wire

Anode Cathode Anode Cathode

+ -

Red

lead

wire

Black

lead

wire



This small reverse current flows until the diode reaches the zener breakdown point, V2 in figure.

At zener breakdown point, the zener diode is able to maintain a fairy constant voltage as the

current varies over a certain range.

Because of this attribute, the diode provides excellent voltage regulation.

3) Zener diode usage

An electronic device that can be used as a voltage regulator is the zener diode.

4) Example of circuit that use zener diode

- Zener diode breakdown voltage of circuit below is 12 V.

- Supply voltage to controller through C1 in circuit diagram below shall never exceed 12 V.

- If supply voltage exceeds 12 V then it is earthed through zener diode.

So, because current is extinguished through earth for voltage above 12 Volts any voltage above

12 Volts is not supplied to controller.

Voltage

remains

constance

over large

current

range

Forward bias

Reverse

bias

－

＋

＋

Current

V2 Voltage 0

Zener

breakdown

region

Zener diode characteristic



6.2 Photo diode

1) Photo diode symbol

2) Photo diode characteristic

Electric current flows if lighted on PN junction surface under condition where certain voltage is

applied in backward direction. And if light irradiation dose is changed, electric current changes in

proportion to the light quantity. Electric potential barrier is made on PN junction surface and

becomes greater if reverse voltage is applied so as to become a complete insulator. If light is

shed on PN junction surface under this condition, change arises on the junction surface.

Respectively electron and hole are activated by external light energy along with positive (+) ion in

N side area and negative (-) ion in P side area . Hole and free electron separated from

respective ions move along so that electric current gets to flow. Thus diode is used in light →

electricity transformation circuit .

Whence if voltage is maintained constant , electric current flowing in circuit gets proportional to the

light quantity received by element .

ZD 12Volts Condenser

R1

R2

R3

R4 Controller

Supply

Voltage

TR

Earth

Earth

C1




3) Example of circuit that use photo diode

- Photo diode has been connected in backward direction in circuit below.

- If light irradiates on photo diode, then because battery voltage is supplied, the lamp turns on .

- It is much used as a switching circuit .

6.3 LED (Light emitting diode)

1) Photo diode symbol

2) Light emitting diode characteristic

This diode is that which illuminates as electric current flows by applying forward voltage at PN

junction diode. Its characteristics are as follows :

- It has longer life and electric power consumption is smaller in comparison to incandescent

electric lamp.

- Response is speedy.

- It illuminates even with low voltage of 2~3 V.

- Power consumption is small (about 0.05 W ) ,

- Response of turning on and off is quick (by unit of millionth second).

- As for illumination color, there are red, green, yellow etc. according to semiconductor material.


Photo diode

Battery 12 volts Lamp

Photo diode circuit



3) Example of circuit that use zener diode

- If switch is closed in circuit below, then electric current flows so that LED illuminates.

- As for role of resistance, it was used for voltage drop to apply a voltage of 3 V at LED.

4) Trip computer display using a LED

Photo diode circuit

Battery

9 Volts. 3 Volts

Switch

LED



7. Transistor

7.1 What’s transistor?

PNP type transistor is that where thin N type semiconductor in a semiconductor crystal has been

inserted between two P type semiconductors while NPN type transistor is that where thin P type

semiconductor has been inserted between two N type semiconductors. For symbols in semiconductor,

E denotes emitter terminal, B denotes base terminal and C denotes collector terminal

Each Part Symbol and Sorts of Transistor

Transistor according to association of semiconductor, there are PNP type and NPN type.

And, transistor according to usage and type, following name is attached.

2SA××× ----- For high frequency transistor of PNP type

2SB××× ----- For low frequency transistor of PNP type

2SC××× ----- For high frequency transistor of NPN type

2SD××× ----- For low frequency transistor of NPN type

D: For low frequency

transistor of NPN type



7.2 Basic operation of transistor

7.2.1 Basic operation of NPN type transistor

This type has been connected in opposite case to PNP type; but in this NPN type, as shown in

figure below, a few holes are supplied from positive pole of electric source so that these make a

small portion current of base current IB. And electrons that come from emitter as not having been

able to join with base holes move to collector side owing to VCB of collector side so that these make

collector current IC. Ordinarily 95~98 % among emitter current IE becomes IC but remainder 2~5 %

becomes IB.

Current Ib

Emitter(E)

Base(B)

Vbe

NPN type

Vcb

Current Ic

Collector(C)

Forward bias of NPN type transmitter:

Emitter's electron most moves by collector

Ib

[uA]

Ic [mA]

<Base electric current and

collector electric current>

P

Type

N type

PNP type transmitter structure & symbol >

Collector(C

) P

Type

Emitter

(E)

Base (B)

Collector(C

)

Emitter

(E)

Base (B)

Collector(C

)

Emitter

(E)

Base (B)

N

Type

P type

NPN type transmitter structure & symbol

N

Type

Base (B)

Emitter

(E)

Collector(C

)



7.2.2 Basic operation of PNP type transistor

If forward voltage VBE is applied between emitter and base, electric potential barrier in between PN

junction surface becomes low. And at P type side of emitter side, many holes are being generated

because impurity material concentration has been heightened, And as for base N side, because this is

very thin so that impurity material concentration becomes lower, there are only few electrons.

Accordingly holes in emitter cross over the electric potential barrier and enter the base side by

diffusion so as to vanish by bonding with a part of base electrons there. But because these few

electrons are continuously supplied by negative “-“ pole of electric source, these make the small base

current IB.

If backward voltage VC B is applied between base and collector, electric potential barrier is heightened

at PN junction surface so that electric current does not flow between base and collector.

Holes that could not join with base electrons but come from emitter now move to collector side owing

to VCB of collector side. These make collector current IC . Emitter holes are gradually supplied from

positive pole so that these make emitter current Ic. Accordingly most IE becomes IC but very little

portion becomes base current IB.

7.2.3 Amplification function of transistor

As we have already discussed above in `Basic Operation', most electron (no less than 95 %) move to

collector but only a few electrons (no more than 5 %) join with base hole. So as electron current and

electric current direction are ordinarily defined oppositely while emitter current EI is divided into

collector current CI and base current BI , the following equation holds :

CBE III

Like this, big collector current may be deduced from small base current so as to be called electric

current amplification while relationship (ratio) between BI and CI are called electric current

amplification factor (hFE).

For calculation example, if BI is 1 mA and CI is 100 mA then hFE is 100. Namely it means

transistor that can amplify input signal by hundred times. (*Electric current amplification rate of

transistor varies according to usage, sort etc . )



B

C

I

IhFE

, 100

1

100

Meanwhile in how to use transistor, there are three earth methods of emitter earth, base earth and

collector earth among which the emitter earth method as in circuit above is most used.

.

And generally amplification means that of alternating current component , which we shall deliberate in

the following example :

In circuit shown in figure here, if AC signal is applied between base and emitter, base current BI

flows only when it is in forward direction (same as in diode). Whence collector current CI also

appears as output while being amplified only of half wave. Namely transistor does not operate

during negative (-) half cycle because here it is in backward direction between base and emitter.

Here let us apply DC between base and emitter. If AC is applied onto DC, AC component is added

upon DC so as to appear like what is shown in the following figure.

Ic=100mA

Ib=1mA

B

E

C hFE=100

Input

(Ib=uA)

Output

(Ic=mA)

B

E

C

Input

Output



Voltage at this time is called bias voltage. Now for the first time we can see completely amplified

output waveform. Also we may obtain the amplified AC waveform only if we remove DC component by

connecting a condenser at output terminal.

To avoid inconvenience of using two electric supplies due to bias voltage as in the depicted circuit ,

actual circuits use various forms adequate to purpose of each circuit by such as an electric current

feedback bias, a fixed bias using a resistance, condenser etc. on the supply electricity source

connected to the output terminal..

* For reference to say, there is limit area where collector current does not increase any more even

though transistor base current continues to increase so as to be called the saturation region.

Accordingly transistor 's amplification action is accomplished only in specific area where collector

current increases in accordance with base current increase so as to be called the active area .

So far we have learned electric current amplification but now let us think case of voltage amplification .

According to the above explanation, we learned that collector varies proportionately with base current .

Let us think this as a variable resistor to control electric current . Then we can think the following

equivalent circuit .

Input

(Ib=uA) B

E

C

Input

Output

Bias voltage

Output

(Ic=mA)



Under condition as above, output voltage to the base input waveform shows up reversely as may be

seen in figure. It is explained as total voltage E = voltage drop between collector and emitter (Eo) +

voltage drop due to resistance R (Ic × R). Namely, if electric current Ic increases, voltage drop due

to resistance R also increases so that the output voltage Eo decreases. (Output voltage Eo = E –

(Ic × R))

Output

(Eo)

R

E

Current Ic B

E

C

Current Ic

Output (Eo) R

E

<Equivalent circuit>

Output Current

(Ic=mA)

Output voltage

(Eo=E-(Ic*R)

Input current

(Ib=uA)



Now let us learn base earth and collector earth methods along with transistor 's switching action.

Base earth circuit

Method of base earth is type of circuit as shown in figure to take base as earth and apply input signal

to emitter.

If there is no electric potential difference between emitter and base, emitter current does not flow as

well as their flows no electric current at collector where voltage is applied in backward direction

through resistance. If forward voltage is applied between emitter and base as in circuit shown by

figure, collector current may also flow through resistance.

In this case, because sum of base current and collector current is equal to emitter current , ratio of

collector current to emitter current is below 1 so that electric current is not amplified.

In case of voltage amplification, if we suppose for example that 10mA flows in emitter, then some

1mA and 9mA flows in base and collector respectively so that voltage drop occurs, through

resistance, in collector that is the output .

Accordingly it becomes 9mA × resistance [kΩ] = output voltage so there is accomplished voltage

amplification to the input signal .

B

E C

Input

Output

<Base earth circuit



Collector earth circuit

Method of collector earth is type of circuit as shown in figure to take collector as earth , send input

signal to base and send output from emitter.

In emitter earth circuit , collector current greatly varies according to base current while variation of

value of load resistance connected to collector does not give large effect to electric current . But in

collector earth circuit , because forward voltage is applied between emitter and base for output circuit ,

emitter current (from collector to emitter) flows so as to be applied at load resistance as it is .

Accordingly emitter current is controlled by small base current as well as emitter current varies directly

also by load resistance variation .

As above, we learned three types of earth methods according to terminals used in common . Among

them the most general and usually used method is emitter earth method whereas to summarize it

may be explained by the following characteristics table.

.

Characteristic of earth methods

Item Emitter Earth

Circuit Base Earth Circuit

Collector Earth

Circuit

Electric current

amplification degree High Low Mid

Voltage amplification High Mid Low

Electric power amplification High Mid Low

Input impedance Mid Low High

Output impedance Mid High Low

Phase of output to input Antiphase Inphase Inphase

High frequency

characteristics Bad Best Good



To understand amplification circuit that use transmitter

Circuit description

- The R1's resistance changes NPN transistor base and bias that is approved to emitter voltage to 3

volts. There is serving resistance

- Variable resistor is thing to control NPN transistor's bias voltage by 0 ~ 3 volt

- That is, become transistor's base and emitter bias voltage high if variable resistance value is high,

and resistance value two. If is low, bias voltage becomes low

- Therefore flowing electric current is passed much to collector and emitter according to bias voltage

- Therefore, can control turning number of motor according to position of variableness resistance

passing as motor's electric current by bias voltage differs.

CBE III B

C

I

Ih F E

hFE:The electric current amplification rate,

IB:Base current,

Ic:Collector current)

R1=1

12V D235 (NPN TR)

1~100Ω

variable resistor

Base

Emitter

Collector

M

Motor



7.2.3 Switching function of transmitter

In explanation of amplification action, we learned that if to electrify between emitter and collector, it

would do making the base current Ib to flow. Namely it will do if we supply base current up to

saturation state where collector current will not almost increase any more. (Nevertheless in small

signal amplification circuit or ordinary home appliances, usually use is made of amplification action

not in saturation region but in active area . ) We can turn on / off circuit between emitter and collector

by on / offing the base current Ib under this condition . This is called transistor 's switching action

among transistor 's amplification action..

We can make role like of relay if using transistor 's switching action as shown in figure.

Transistor 's base current corresponds to relay 's excitation current so that transistor may act as the

relay while not using mechanical contact as in relay 's contact point . And if load increases then

electric current Ic also increases, whereas, when we cannot supply sufficient electric current by a

transistor, we can make use of electric current amplification by means of connecting transistors in

multistage in accordance to load capacity.

So transistor 's switching action has the following advantages to the relay.

- Switching speed is fast (more than thousand times per second).

- Operation is stable and there is no chattering when on / offing the contact point as that in relay

because there is no mechanical contact . It is small type with less electric power consumption .

It has longer life than mechanical relay.

Batt ON/OFF input signal

Load

Switching relay

B E

C Current

Ic

Batt

ON/OFF

Input signal Load

Switching transmitter



To understand transistor switching circuit

1. In below circuit, when ignition key switch does ON, power is supplied to the ignition coil.

2. If supply power to power TR Base from ECM through Pin No23 ignition coil of electric

current passes by ground G11.

3. Again ECM transmitter's base power when coil's electric current is shut off because

connection between collector and emitter becomes open if do Off in coil high tension

generate become.

From ignition key switch

Pin No 23

Ground G11



7.3 Judgment of good / b ad transistor

As may be seen in figure, it will be fine if we think transistor to have been connected with part of

emitter and base considered as a PN junction diode and part of base and collector considered as

another diode..

1. When multi-meter measures between B~E and B~C in forward direction under normal condition,

it is electrified ( showing ordinarily some hundred mV in case of digital meter but a low resistance

value in case of analog type meter). Inversely when measured in reverse direction, it is not

electrified so that there is little change in indication value of multi-meter (by which there is

displayed a voltage same as for case when measuring rod was not connected in case of digital

meter while there is displayed an approximately infinite resistance value is displayed in case of

analog meter).

2. Next if also measured for interval of E~C forwardly and backwardly with the measuring rod, there

is little change in indication value of multi-meter for both of the reciprocal cases because it is not

electrified for both cases. Whereas in some cases according to transistor sort and characteristic

when red (+) rod is connected to collector and black (-) rod is connected to emitter (in case of

NPN, but reversibly in case of PNP), quite a high resistance value may be displayed even though

it would not be infinite (so namely a little current may flow).

For reference to say, when testing transistor or diode, if measuring under condition where it has been

connected to circuit , it may be affected by connected circuit resistance value, it is desirable to

measure under condition isolated from circuitry. And in case where generally transistor or diode has

been broken , it is displayed as primarily short circuit form .

Base Base

Collector Emitter

NPN Transmitter Base

Emitter Collector



Polarity distinction of transistor

1. In case of using analog multi-meter.

1) Put mode switch in Analog multi meter at R100 or R1000 with in measurable range.

2) First connect a lead wire to any pin in transistor. Then connect left 2 terminals in

transistor respectively, using other lead wire.

3) At this moment, if the direction becomes CW, which resistance measuring becomes

nearly OΩ, black lead wire connection becomes base line in NPN transmitter and red

lead wire connection becomes base line in PNP transmitter.

4) If you set mode switch in R1000 at circuit tester, result in CW direction after measuring

other two pins’ resistance respectively, red lead wire connection becomes collector in

NPN and black lead wire becomes collector in PNP.

Multi Meter Multi Meter

Base

1 2 3

1 : Collector

2 : Emitter

3 : Base



2. In case of find polarity to use transistor's lead wire.

When saw flat side that printed of part name.

In case of 2SC1815 transistor (NPN type transistor for

high frequency)

- Right side lead : Base

- Center side lead : Collector

- Left side lead : Emitter

Emitter Base

Collector

Base

Collector

Emitter

In case of 2SD880 transistor (NPN type transistor for high

frequency)

- Right side lead : Emitter

- Center side lead : Collector

- Left side lead : Base



8. Thermistor

To semiconductor element that use change of resistance according to temperature, there are NTC

thermistor and PTC thermistor

8.1 NTC (Negative Temperature Coefficient) thermistor)

- Characteristic

If temperature rises, there is characteristic that resistance decreases

- Usage in car

Engine coolant temperature sensor, Air intake temperature sensor, and Low fuel-warning sensor

Temperature

Resistance

Engine coolant temperature sensor



- To understand circuit usage PTC thermistor.

NPN transistor's bias voltage depends on NTC thermistor in below circuit

If temperature rises, voltage between base and emitter is raised.

Therefore, TR does ON and lamp turned “ON”.

8.2 PTC (Positive Temperature Coefficient) thermistor)

- Characteristic

If temperature rises, there is characteristic that resistance increases

- Usage in car

Central door lock actuator

- To understand circuit that use NTC thermistor.

In below circuit, lamp turned ON when switch ON.

If excess current is passed to ramp, heat by excess current is occurred to thermistor

At this time, thermistor's resistance increases and decreases electric current.

Therefore, prevent over current in circuit.

NPN TR

12 Volts Battery

Lamp

R1

NTC

Thermistor

Battery

Lamp Thermistor

Switch



9. Photoconductive cell

According to brightness of light, value of resistance changes.(increase or decrease) .

Material that convey light is Cds (Cadmium sulfide) and CdSe (Cadmium selenide)

- Characteristic

Resistance decreases if brightness of light is strong, and there is Characteristic that resistance

increases if light becomes feeble

- Usage in car

Auto light sensor, FATC air conditioning system

- To understand circuit that use CDS

1) If transmitter1 does ON, lamp turned ON.

2) For TR1 does ON, TR2 must do ON

3) TR2's ON operates according to cds's resistance value

4) If receive a lot of raises in CDS, TR2 does ON because TR2's bias voltage rises

5) If quantity of light decreases, TR2's bias voltage decreases, because cds's resistance

increases lamp Off

1 10 100 1,000 Lux

KΩ

10,000

1,000

100

10

1



10. Piezo-electric element

If receive pressure, if electromotive force happen, and supplies voltage, there is special quality that

cause transformation

- Material : Titan acid, Barium

- Usage in car : Knock Sensor

- Knock sensor waveform

a. Cylinder Pressure Signal

b. Filtered Cylinder Pressure Signal

c. Knock Sensor Signal

R1=10

R4=4.7

R2=4.7

R3=1 cds

Lamp

NPN TR1

2SC372

12 volts

BATT.

NPN TR2

2SC372

Circuit that use Photoconductive cell

Knock sensor



11. Hall effect

When you put hall IC in magnetic field at concentric position with current flowing, both hall IC end can

produce some voltage.

In the following picture, if you put any conduct in magnetic field and make some current flow through

this, A1 and A2 can produce some voltage out.

If you simulate the magnetic field then the output voltage between A1 and A2 becomes on and off.

When tone wheel destroy the magnetic filed the output voltage between A1 and A2 in the following

picture, becomes on. When this tone wheel reaches without any damage to the magnetic field the

output voltage becomes off

A1

A2

Iv

Current “I”



- Usage in car

CMP sensor, CKP sensor, Speed sensor ect.

- Signal waveform

Time

Volt

Hall IC type CMP sensor



12. Integrated Circuit (I.C)

12.1 Integrated circuit general

An integrated circuit or IC is several hundreds of resistors, transistors and other elements formed

on a substrate to function as if they were single device. When reading a circuit with an IC,

understanding of the operating conditions as indicated by the timing chart or table is important. In

this chapter, how a circuit with an IC should be read will be described.

Type of I.C

Classification by Scale of Integration

SSI (Small Scale Integrated Circuit) : Less than 100 elements

MSI (Medium Scale Integrated Circuit) : 100 to 1,000 elements

LSI (Large Scale Integrated Circuit) : 1,000 to 100,000 elements

VLSI (Very Large Scale Integrated Circuit) : 100,000 or more elements

Classification by Application and Structure

Analog IC I.C amplifying or controlling analog quantity (continuous quantity)

Output signal always changes linearly with the input signal

This type of IC’s is widely used in units using analog circuits.

Digital IC I.C that performs switching only. According to input ON/OFF signal conditions,

the output is obtained as ON/OFF switching signal.

Input Output

Input Output



Features of I.C.

Size reduced to minimum by integration

High reliability thanks to integrated structure

Low price thanks to volume production

Low power consumption

12.2 Analog I.C

The IC shown here is one called comparator.

“a” is the power supply terminal and “b” is the ground terminal, both are required to supply power to

the comparator for its operation but are not directly associated with the operation itself.

The comparator compares the potential at terminal c and terminal d and in this operating conditions

shown, it gives output va[v] at point e only when the potential at point c is higher than the potential at

point d.

Of the two input terminal voltages, one that remains constant is called the reference voltage and one

that changes is called the comparison voltage which of the two input terminals has the reference

voltage can be known from the circuit connected to the comparator.

＋

+

c

d －

＋

c

A (Va)

b

(Vb)

Vc Vd

Operating conditions

Output(Va volt) is made when Vc＜Vd

Output(Va volt) is not made when Vc≤Vd



12.3 Digital I.C

Logic circuit

In a digital circuit, two signals are used, that is, signal with high voltage (H) and signal with low

voltage (L) or presence of signal and absence of signal.

And as a convention, these two signals are represented by “1” and “0”.

For example, when the transistor is off in this figure, Vce is 12V and this state of voltage is taken as

“1”.

When the switch is set to ON to turn on the transistor, VCE becomes 0V and this state is taken as

“0”.

In a digital circuit unlike an analog one, various information is expressed by combination of only two

signals that can have only two states, namely, “1” or “0”.

A logic circuit is a circuit that gives an output “1” or “0” when input signal that is combination of “1”

and “0” is applied.

Vce

Switch

12 volts

Battery

ON

12 volts

0 volts

Vce OFF OFF OFF

ON ON TR



12.4 Various logic circuits

12.4.1 AND circuit (logical product)

And operation is the operation that gives a result only when all conditions are met such as “the

brake warning lamp lights up when the ignition switch is ON and the parking brake switch is ON”.

Namely, the AND circuit is a circuit of which output signal becomes “1” when the input signals are

all “1”.

Representation Actual Circuit Logic Symbol Input/Output relation

A B C

1 1

1 0

0 1

0 0

1

0

0

0

This figure shows an example of AND circuit using transistors. When both input signals A and B

are 1(H), 1(H) voltage is obtained at output C.

For output C to be high, it is necessary that both Tr2 be off and for these two transistors to be off,

it is necessary that Tr1 and Tr2 be on. And for Tr1 and Tr2 to go on, high (H) voltage must be

applied to inputs A and B so that base current may flow to both transistors.



12.4.2 OR circuit (logical sum)

OR operation is the operation that gives a result when at least one condition among various

conditions is met such as “when any one door is opened, the door ajar indicator lamp lights up”

Namely, the OR circuit is a circuit whose output becomes “1” when at least one input signal is “1”.

In contrast to the AND circuit whose output is “1” when all inputs are “1”, the OR circuit may be

considered as a circuit whose output is “0” when all inputs are “0”.


A B C

1 1

1 0

0 1

0 0

1

1

1

0

This figure shows an example of OR circuit using transistors.

When either input A or input B is “1” output C becomes “1”.



12.4.3 NOT Circuit (negation)

The NOT circuit is a circuit whose output is inverse of the input, such as when the input signal is

“1”, the output signal is “0” or vice versa.

For this reason, the NOT circuit is sometimes called an inverter.


A B C

1 1

1 0

0 1

0 0

1

1

1

0

Note : The relationship between transistor base voltage (VBE) and collector voltage (VCE) is NOT

relation.

Namely, when the base voltage is high, the transistor goes on and hence the collector voltage

becomes low. On the other hand, when the base voltage is low, the transistor goes off and

hence the collector voltage is high.



12.4.4 NAND and NOR circuits

The NAND circuit is an AND circuit followed by a NOT circuit and for this reason, it is called

NAND (meaning NOT + AND)

Logic Symbol Input/Output relation

Input Output

A B Y

L

L

H

H

L

H

L

H

H

H

H

L

12.4.5 The NOR circuit is an OR circuit following by a NOT circuit.

In either circuit, the output is the inverse of the AND or OR circuit.

Logic Symbol Input/Output relation

Input Output

A B Y

L

L

H

H

L

H

L

H

H

L

L

L



MEMO



13. Microcomputer

The microcomputer is a kind of computer. Let’s now review briefly the history of development of

computers.

The first computers ever produced were mechanical ones using gears and other mechanical

parts, which was followed by electric ones using relays and them by electronic computers using

vacuum tubes. An electronic computer using vacuum tubes was large enough to occupy an entire

room of a building, with an many as 20,000 tubes in use. These vacuum tubes were then

replaced by transistors and then by integrated circuits (IC). The degree of integration of these Ics

then became increasingly higher, developing to LSI (large scale integration) and VLSI (very large

scale integration) With these developments, computers also changed from vacuum type to

transistor type to IC type and then to current LSI type, with their size becoming increasingly

smaller.

Let’s now see how microcomputers were born.

When development was under way to make electronic portable calculators more compact and

more sophisticated, every design change required redesign of LSI, which required very large cost

and time. This problem was coped with by the use of LSI that allowed free change of internal

functions by program. Namely, with such LSI, you can change the programs to allow

development of new calculators. And such LSI whose internal functions could be freely changed

by program modification was a microcomputer. In other words, a microcomputer is an LSI with

functions that are described in the following.

13.1 Three elements of microcomputer

A microcomputer consists of three elements, CPU (central processing unit) memory and I/O

(input/output unit)

13.2 I/O unit (Input / output unit)

Through this unit, the microcomputer communicates with external units (sensor, switch, actuator,

etc.) In the case of ECU for instance, the intake air amount is input to the microcomputer as a

sensor signal and the result of calculation by the CPU is output from this I/O as the fuel injection

amount control signal.

13.3 Memory

The memory stores the program (set of directions for operation, judgment, data exchange, etc.),

data (reference voltage for ECU air/fuel ratio comparison, for instance) and signals that are input

while the CPU is busy with calculation processing.

The memory is generally classified into the following two types.



13.4 ROM (Read Only Memory)

A Memory for read only. In the case of a microcomputer for automotive application, only one fixed

program needs execution and for this reason, the program is permanently stored in a ROM. The

ROM is nonvolatile. The contents are held permanently even after power is turned off. This

nature makes ROM optimum device for storing programs.

13.5 RAM (Random Access Memory)

Memories that can be write in and read from. It is used for temporarily storing data. Normally it is

volatile and the contents stored are lost once the power is turned off.

Note : Nonvolatile RAM is also available that is called NVRAM. It is used in electronic odometer,

for example.

13.6 CPU (Central Processing Unit)

The part of a computer, that performs operation, interpretation and data exchange according to

the program stored in the memory.

Take the O2 sensor of ECM as an example. When the voltage signal indicating the air/fuel ratio

arrives at the I/O unit from the O2 sensor, the CPU makes processing according to the program

stored in the memory in the following manner.

The CPU compares this signal with the reference voltage stored in the memory and if the signal

voltage is higher, it judges that the air/fuel ratio is higher than the theoretical air/fuel ratio and

outputs the signal for lowering the fuel injection rate to the I/O. Then, the I/O sends out this signal

(to the injector) so that the fuel injection rate is reduced.

13.7 Types of microcomputer

The microcomputers can be divided into two types depending on whether separate LSI

implements its three elements or all these elements are implemented by a signal LSI.

The former type is called a multi chip microcomputer and the latter type is called a one hip

microcomputer. The microcomputers used in a car mostly belong to the latter category.



13.8 Basic operation of microcomputer

The basic internal operation of a microcomputer is addition and subtraction of binary numbers

and the internal circuits are basically logic circuits. Namely, the microcomputer is essentially

digital IC and its internal circuit can be represented by logical symbols. The internal circuits of a

microcomputer for automotive application are complicated but they are relatively easy to

understand if you have basic knowledge of logic circuits.

Note : Binary number

The numbers 0 through 9 we use in our daily life are decimal numbers. Binary numbers, on the

other hand, consist of only two numbers of 0 and 1. These two numbers correspond, as you will

be aware, to the two signals of a logic circuit. In other words, a microcomputer is a digital IC that

processes binary data by its logic circuit.

13.9 Microcomputer in a system

15.9.1 Use as a controller

In a system formed by transistor, IC, LSI and other individual parts, a microcomputer is

introduced as a controller. Typical examples are TV and radio sets and other household electric

and electronic appliances.

15.9.2 Use as a computer

Application with emphasis placed on its calculation function.

Personal computers and word processor belong to this category.



15.9.3 Combined use as controller and computer

Use of a microcomputer not for simple control of machine, but for optimum control.

Namely, the microcomputer judges conditions that are constantly changing and controls the

machine adequately. Microcomputers used in a car belong to this category.

15.9.4 Example of application

As an example of practical application of microcomputers to cars, the computer unit for ECM

will be descried.

This computer unit of ECM computers the optimum fuel supply rate to the engine, etc. with its

microcomputer.

Signals from various sensors are input via the I/O unit and calculated by the CPU according to

the program stored in ROM.

In memory (RAM), data and calculation results are stored temporarily as necessary.



14. To understand electronic circuit

Blower motor speed control circuit

Room lamp delay control circuit

R1

1

Battery

12volts

TR

D235

VR

1~100Ω

B

E

C

M

Blower Motor

IB

IC

Explain process that blower motor's speed is controlled according to value of VR

(variable resistance).



Auto lighting circuit

TR 2

D471

TR 1

A1015

12Volts

Battery

Room Lamp

12Volts/1.2W

R 1

330Ω

Condenser

33/25Volts

Door Switch

Diode 1

10D1

R 2

15 Diode 2

10D1

R 1

10

C

B

E

C

B

E

Explain process that room lamp operates according to ON/OFF of door switch in above

circuit.



R3

10

R4

4.7

R 1

4.7

R 2

1 cds

LED

TR 1

2SC372

TR 2

2SC372

Battery

6V

C

B

E

C

B

E

Explain process that LED lamp operates in above circuit diagram.

MEMO



APPENDIX

Electric unit symbols



Quantity Unit Unit Symbol

Current Ampere A

Voltage Volt V

Electric Resistance Ohm Ω

Conductivity Mho

Quantity of electricity

Coulomb C

Ampere-hour Ah

Electric power Watt W

Work of electricity

Joule J

Watt-hour Wh

Static capacitance Farad F

Electromagnetic induction

Coefficient He H

Magnetic flux Weber Wb

Magnetic field intensity Ampere-turn AT/m

Magnetic force Meter

Magneto motive force Ampere-turn AT

Frequency Hertz Hz

Sound level Phon P

Attenuation or gain Decibel dB



Multiplier fraction Prefix Symbol

106 Mega or Meg M

103 Kilo K

10-1 Deci d

10-2 Centi c.

10-3 Mili Mm

10-6 Micro

10-9 Nano n.

10-12 Pico or Micro p.

PREFIX SYMBOL RELATION TO

BASIC UNIT EXAMPLE

MEGA

KILO

MILLI

MICRO

NANO

PICO

M

K

m

µ

1 000 000

1 000

.001

.000 000 001

.000 000 001

.000 000 000 001

8 M = 8 000 000

20 Kv = 20 000 V

500 mV = .5 V

500 µA = .000 5 A

20 V = .000 000 02 V

20 V = .000 000 000 02 V

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