© 2008 Snap-on Incorporated; All Rights Reserved

2 © 2010 Snap-on Incorporated; All Rights Reserved2 Course Objectives This module covers: –Electronic Principles –Electronic Devices –Electronic Measurements –Solid State Devices –Schematic Symbols –Good Info to Know

3 3 Electronic Basics

4 4 Electricity starts in the atom.

5 5 Electronic Basics Electricity is the flow of electrons (-) from one atom to another.

6 1.Electricity is flow of what part of the atom? Review for Understanding

7 7 Electronic Basics - Flow Direct current (DC) flows in one direction. 5 volts DC is often used in computer systems Charging voltage is often about 14.2 Volts DC

8 8 Electronic Basics - Flow Alternating current (AC) changes direction. AC voltage needs to be rectified to DC in order to be used by computer systems

9 9 Electronic Basics - Flow For discussion purposes, electricity is either conventional flow or electron flow.

10 Electronic Basics - Materials Conductors are materials that have less than 4 electrons loosely held in their outer orbit.

11 Electronic Basics - Materials Insulators are materials that have more than 4 electrons tightly held in their outer orbit.

12 Electronic Basics - Materials Semi-Conductors are materials that have exactly 4 electrons in their outer orbit. Semiconductor materials are the building blocks of electronic components

13 Electronic Basics - Materials Semi-Conductors are materials that have exactly 4 electrons in their outer orbit. Carbon (C), Silicon (Si), and Germanium (Ge), are the materials used to manufacture resistors, diodes and transistors.

14 1.How are conductors & insulators different? 2.Explain AC & DC. 3.Name 2 materials used to manufacture semiconductor devices. Review for Understanding

15 Electronic Basics – Measurements Amperage is the unit for measuring the rate of electrical current flow. Important to know because of transistor current gain factor.

16 Electronic Basics – Measurements Voltage is the electrical pressure or force that causes electrons to flow. Important to know because of diode forward bias voltage drop

17 Electronic Basics – Measurements Resistance to flow is measured in Ohms and abbreviated with the Greek letter Omega. Ω Important to know because resistance causes heat.

18 Electronic Basics Semiconductors are materials with exactly 4 electrons in their “valence rings”. They can change function and become either conductors or insulators. Add an electron = 5 Subtract an electron = 3 Semiconductor materials are used to build “solid state” devices.

19 Electronic Basics Semiconductors are used to build “solid state” devices. Solid state devices control electrical flow without any moving parts!

20 Electronic Basics Semi-conductors carry current w/o losing electrons through the concept of hole flow. Holes in a P-type material, being positively charged, attract electrons causing movement.

21 1.What is the unit of measure for electromotive force? 2.What is the unit of measure for current flow 3.What is the unit of measure for resistance to flow? 4.What is the general meaning of the term “solid state”? Review for Understanding

22 Electronic Basics - Components The diode is the simplest semiconductor device. It is a one-way valve for electron flow.

23 Electronic Basics - Components Diodes turn on (conduct) when the polarity of the current flow is correct. Diodes turn off (block flow) or (OL) when the polarity is incorrect.

24 Electronic Basics - Components Diodes are popular in charging systems where they are assembled into a “bridge” and are used to “rectify” AC to DC.

25 Electronic Basics - Components A single diode can do half-wave rectification of AC to DC. Multiple diodes assembled In a bridge can do full-wave AC to DC rectification

26 Electronic Basics - Components The diode contains a P - N junction. (P = positive & N = negative) A diode conducting electricity is said to be forward biased and will typically have a voltage drop of.4 to.7 volts when tested with a DMM Semiconductor testing should always be done using a digital multi-meter.

27 Electronic Basics - Components A diode that is blocking or not allowing flow is said to be reverse biased. A reverse biased diode reads OL when checked with the diode test mode of a DMM. OL.4 to.7 Voltage Drop

28 Electronic Basics - Components A diode reading zero in both directions is shorted & conducts all the time. An open diode reads OL both ways & never conducts at all L Open Shorted

29 Electronic Basics - Components Light Emitting Diodes have a higher forward bias voltage drop then regular diodes. LED’s illuminate when forward biased. They do not illuminate when blocking.

30 Electronic Basics - Components Zener diodes allow reverse polarity flow with out damage after their “threshold voltage” or “zener voltage” is reached. They are used often in charging system voltage regulator circuitry.

31 Electronic Basics - Components Clamping diodes are regular diodes connected in parallel across coils of wire to prevent component damage from induced voltage spikes returning to the PCM and other electronic components as the coil circuits are opened. AC Clutches, relays, & vacuum switching solenoids all need clamping diodes.

32 1.What is the main purpose of a diode? 2.Explain diode forward bias. 3.Explain diode reverse bias. 4.How does a zener diode differ from a regular diode? 5.How is a diode connected to act as a voltage spike clamp? 6.What is the best type of meter to use for diode testing? Review for Understanding

33 Electronic Basics - Components The transistor is a solid-state switching device.

34 Electronic Basics - Components The transistor has legs labeled E, B, and C.

35 Electronic Basics - Components A transistor can be considered as two P-N junctions placed back to back. One of these, namely the base emitter junction is forward biased, while the other, the base collector junction is reverse biased.

36 Electronic Basics - Components When a current is made to flow in the base emitter junction, a larger current flows in the collector circuit even though the base collector junction is reverse biased. Simply put: If E to B is completed with a small current flow, Then E to C passes a greater amount of current

37 Electronic Basics - Components The transistor is a fast-acting, solid state switch, sometimes called a solid state relay.

38 Electronic Basics - Components A negative voltage (ground) must be applied to the base of a PNP transistor to turn it on.

39 Electronic Basics - Components A positive voltage (hot) must be applied to the base of a NPN transistor to turn it on.

40 Electronic Basics - Components Transistors carry current without losing electrons through the concept of hole flow.

41 Electronic Basics - Components In a relay, if 85 to 86 is energized, then the contacts between 30 & 87 close. In a transistor, if E to B is completed, then E to C closes.

42 Electronic Basics - Components In a relay, small current through 85 & 86 can switch a larger current through 30 & 87. In a transistor, small base current can switch a larger collector current.

43 Electronic Basics - Components

44 1.What is the main purpose of a transistor? 2.Using If : Then, explain transistor operation. 3.When does a PNP transistor switch on & conduct? 4.When does a NPN transistor switch on & conduct? 5.Why might a transistor be called a solid state relay? Review for Understanding

45 Electronic Basics - Components Capacitors can store an electrical charge for a short period of time They are used as back-up power supplies in automotive air bag systems

46 Electronic Basics - Components A resistor offers an opposition to electromotive force in a circuit. Carbon Composition Resistors

47 Electronic Basics - Components Resistor values can be determined by using a color code chart.

48 Electronic Basics - Components A thermistor is used to provide compensating voltage in components or act as a temperature sensor as in an IAT or an ECT. They may be NTC or PTC in design.

49 1.What is the basic purpose of a resistor? 2.What is the basic purpose of a capacitor? 3.Thermistors can be used as what engine control sensors? Review for Understanding

50 Electronic Basics – Good to Know An Integrated Circuit (IC or chip) is a large # of diodes, transistors, resistors, capacitors, mounted to a semiconductor material used to make logic decisions & commands.

51 Electronic Basics – Good to Know A microprocessor is a small version of a computer. PCM or any ECU/CPU

52 Electronic Basics – Good to Know Analog voltage signals are infinitely variable. Digital voltage signals are in one of either 3 states: on-off, yes-no, or high-low

53 Electronic Basics – Good to Know Since computers can only read digital, binary voltage signals, analog signals must go though an analog/digital (A/D) converter in order to be used or “understood” by the computer.

54 Electronic Basics – Good to Know Frequency is a term that describes how often a signal performs a complete cycle.

55 Electronic Basics – Good to Know A cycle is a description of the changes that a signal goes through without repeating.

56 Electronic Basics – Good to Know Frequency is measured in Hertz. Hertz is a measurement of Cycles per Second.

57 1.Describe a digital wave. 2.Describe an analog wave. 3.Which axis is voltage on a waveform diagram? 4.Which axis is time on a waveform diagram? Review for Understanding

58 Electronic Basics - Schematics Ground Battery Fuse Circuit Breaker

59 Electronic Basics - Schematics Wire Wires CrossingWire Connector Wire Splice

60 Electronic Basics - Schematics Resistor Variable Resistor Thermistor Stepped Resistor

61 Electronic Basics - Schematics Diode Zener DiodeLight Emitting DiodeRectifier Bridge

62 Electronic Basics - Schematics M G Motor Generator Relay Capacitor

63 Electronic Basics - Schematics Twisted Pair of WiresSwitch Momentary SwitchContacts

64 Electronic Basics - Schematics Coil of Wire Transformer Solenoid Coil Wye- Wound Stator

65 Electronic Basics - Schematics PNP Transistor NPN Transistor Bulb Horn

66 1.What are schematic symbols? 2.Why are schematic symbols used? 3.Can you name the symbols on the following slide without help? Review for Understanding

67 Electronic Basics - Schematics

68 Electronic Basics - Schematics

69 Electronic Basics - Schematics

70 Electronic Basics - Schematics

71 End of BASIC ELECTRONIC Training