1 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Chelmsford Amateur Radio Society Intermediate Course (3) Technical Basics - 1 Components

2 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Electronic Components NatureAmateur Radio applies Electronics to Wireless Communication ItemsCommon Electronic Components Include: –Resistors, inc Colour code –Capacitors, Inductors, Resonant Circuits –Diodes & LEDs –Transistors –Switches, Fuses, Connectors The Intermediate Licence expects you to be able to recognise components, their circuit symbols, and to build and test simple circuits

3 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Conductors permit the flow of electric current –Examples: Copper, Brass etc - (ie mainly metals) Metallic Conductors permit electrons to flow easily, but beware of poor/oxidised connections (eg on Aluminium, Steel) Insulators don’t permit electron flow and exhibit high resistance. –Examples: Plastics, wood, rubber, glass, ceramics Water may conduct (esp. when impure) and that wet insulators therefore may conduct on their surface - a risk for outdoor work Semiconductors (Silicon, Germanium etc) barely conduct unless small dopants are added to create P or N-type materials Insulators, Conductors & Semiconductors

4 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Electrical Units QuantityUnitSymbol Voltage, VVoltVaka Potential Difference Current, IAmpA Resistance, ROhm  CapacitanceFaradF InductanceHenryH Power, PWattW Frequency, fHertzHz Wavelength, Metrem

5 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Unit Prefixes FactorSNPrefixSymbol trillionths picop billionths10 -9 nanon millionths10 -6 micro  or u thousandths millim thousands10 3 kilok millions10 6 MegaM billions10 9 GigaG Examples:25kV = 25000V1500mA = 1.5A 0.1uH = 100nH2.45GHz = 2450MHz 10pF = 0.01nF0.5W = 500mW

6 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Power Relates Power, PVoltage, VCurrent, I P=V x IV=P/II=P/V P Watts V Volts I Amps Recall from Foundation…

7 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Ohms Law Relates Voltage, VCurrent, IResistance, R V=I x RI=V/RR=V/I V Volts I Amps R Ohms NB: Take care when quantities in formulas use unit prefixes

8 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Batteries provide a source of DC power Note symbols for Single Cells or Battery Packs Cells store electrical energy by chemical means Primary Cells can only be used once. Secondary cells can be recharged. This reverses the chemical reaction eg in Lead Acid, NiCd, LiMH Beware of Leakage, Shorts esp on Lead-Acid Dispose of carefully Cells & Batteries   Cell   Battery + -

9 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Fixed Resistors traditionally identified by Colour Code for Value & Tolerance Note that the modern BSI Symbol is preferred to the zigzag Resistors Resistor Variable Resistor Preset Resistor Potentiometer Note all the symbols opposite for the various forms Check Wattage Rating No

10 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components First two Bands give Value Digits Third Band is the Multiplier for Factor of Ten Fourth Band is Tolerance Example:- Resistor Colour Code 12 x1000= 12k, 10%

11 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Resistors in Series:- R total = R 1 + R 2 + R 3... Resistors in Series/Parallel Resistors in Parallel:- 1/R total = 1/R 1 +1/R 2 +1/R 3... For Identical Resistors this simplifies to... For Two Resistors: R total = R/2 For Three Resistors: R total = R/3 R 1 R 2 R 3 R1R1 R2R2 R3R3

12 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Inductors are Coils of Wire which may have air or ferrite/iron cores Energy is stored in the magnetic field Inductance is proportional to number of turns, diameter, core etc Inductance is in Henries eg mH, nH, pH Inductors pass DC but increasingly block AC at higher frequencies Pairs of coils can be used to create Transformers – for PSUs, RF circuits etc Inductors & Transformers Transformer Air-Core Inductor Iron-Cored Inductor

13 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Capacitors are insulated plates, which can store electric charge and energy in the electric field Larger plate areas, the nature of materials between the plates or smaller plate separation will give higher capacitance Capacitance is in Farads eg uF, nF, pF Capacitors block DC but increasingly pass AC at higher frequencies Beware Voltage rating and polarity of Tantalum/Electrolytic versions Note all the symbols opposite Capacitors Capacitor Variable Capacitor Polarised Capacitor

14 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Diodes are PN Junctions of semiconductor materials which only pass current one way Diodes are a key item in PSUs where they rectify AC into DC Note Forward Current and Reverse Voltage ratings, and a small forward bias Voltage Drop LEDs - Light Emitting Diodes Variable Capacitance Diodes – exploits PN Junction Capacitance when reverse biased Zener Diodes - have a precise Reverse Voltage Diodes Varicap Diodes Diode LED

15 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Bipolar Transistors are NPN or PNP junctions of semiconductor material Middle section is the ‘Base’. A small bias current can control a larger flow between Collector and Emitter In FET devices current flow between Drain and Source is controlled Electrostatically by the Gate voltage Depending on the circuit, Transistors can Amplify or Switch - or Oscillate Integrated Circuits have arrays of many Transistors on a single chip Transistors c e b Bipolar NPN Transistor s g d P-Channel Field Effect Transistor (FET)

16 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Current flow in the Collector ( I C ) to the Emitter can be controlled by a smaller bias current in the Base, I B If levels are set correctly, small variations in base current are amplified at the output Current Gain or ‘Beta’ is the ratio of I C /I B ß = I C / I B or, I C = ß x I B For example, a base current of 5mA in a device with Beta=50 controls an I C of 0.25A Transistor Gain collector emitter base NPN Transistor ICIC IBIB

17 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Also need to recognise symbols for Switches, Grounds, Crystals etc, etc Miscellaneous Earth EarphoneLamp Chassis Crystal Antenna Microphone Loudspeaker Fuse Switch SPST Switch DPST

18 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3: v1.2 3-May-2009 (3) Technical Basics -1: Components Recognise Resistors by Colour Code Measure Resistors in Series Measure Resistors in Parallel Learn to Recognise other Components Soldering - correctly without damage Build and test board with resistors and transistor Practicals