Chelmsford Amateur Radio Society Intermediate Course 3 Technical

Chelmsford Amateur Radio Society Intermediate Course (3) Technical Basics - 1 Components Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 1

Electronic Components • Nature Amateur Radio applies Electronics to Wireless Communication • Items Common 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 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 2

Insulators, Conductors & Semiconductors • 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 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 3

Electrical Units Quantity Voltage, V Current, I Resistance, R Capacitance Inductance Power, P Frequency, f Wavelength, Chelmsford Amateur Radio Society Intermediate Licence Course Unit Volt Amp Ohm Farad Henry Watt Hertz Metre Symbol V aka Potential Difference A F H W Hz m Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 4

Unit Prefixes Factor trillionths billionths millionths thousands millions billions Examples: SN 10 -12 10 -9 10 -6 10 -3 106 109 25 k. V = 25000 V 0. 1 u. H = 100 n. H 10 p. F = 0. 01 n. F Chelmsford Amateur Radio Society Intermediate Licence Course Prefix pico nano micro milli kilo Mega Giga Symbol p n or u m k M G 1500 m. A = 1. 5 A 2. 45 GHz = 2450 MHz 0. 5 W = 500 m. W Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 5

Power Recall from Foundation… P Watts V Volts I Amps Relates Power, P Voltage, V P=Vx. I V=P/I I=P/V Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Current, I Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 6

Ohms Law V Volts I Amps NB: Take care when quantities in formulas use unit prefixes R Ohms Relates Voltage, V Current, I Resistance, R V=Ix. R I=V/R R=V/I Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 7

Cells & Batteries • 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, Ni. Cd, Li. MH • Beware of Leakage, Shorts esp on Lead-Acid • Dispose of carefully Chelmsford Amateur Radio Society Intermediate Licence Course Cell + Battery Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 8

Resistors • Fixed Resistors traditionally identified by Colour Code for Value & Tolerance • Note that the modern BSI Symbol is preferred to the zigzag Resistor No • Note all the symbols opposite for the various forms • Check Wattage Rating Chelmsford Amateur Radio Society Intermediate Licence Course Preset Resistor Potentiometer Murray Niman G 6 JYB Variable Resistor Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 9

Resistor Colour Code • First two Bands give Value Digits • Third Band is the Multiplier for Factor of Ten • Fourth Band is Tolerance • Example: - 12 x 1000= 12 k, 10% Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 10

Resistors in Series/Parallel • Resistors in Series: - Rtotal = R 1+ R 2+ R 3. . . • R 1 R 2 R 3 Resistors in Parallel: - 1/Rtotal = 1/R 1+1/R 2+1/R 3. . . • For Identical Resistors this simplifies to. . . • For Two Resistors: Rtotal = R/2 R 2 • For Three Resistors: Rtotal = R/3 R 3 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB R 1 Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 11

Inductors & Transformers • 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 m. H, n. H, p. H • Inductors pass DC but increasingly block AC at higher frequencies • Pairs of coils can be used to create Transformers – for PSUs, RF circuits etc Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Air-Core Inductor Iron-Cored Inductor Transformer Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 12

Capacitors • • 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 u. F, n. F, p. F • Capacitors block DC but increasingly pass AC at higher frequencies • Beware Voltage rating and polarity of Tantalum/Electrolytic versions • Capacitor Variable Capacitor Polarised Capacitor Note all the symbols opposite Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 13

Diodes • 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 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Diode LED Varicap Diodes Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 14

Transistors • • • 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 b e Bipolar NPN Transistor 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 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB c d g s P-Channel Field Effect Transistor (FET) Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 15

Transistor Gain • • • Current flow in the Collector (IC) to the Emitter can be controlled by a smaller bias current in the Base, IB If levels are set correctly, small variations in base current are amplified at the output Current Gain or ‘Beta’ is the ratio of IC/IB ß = IC / IB IC base IB collector emitter NPN Transistor or, IC = ß x IB • For example, a base current of 5 m. A in a device with Beta=50 controls an IC of 0. 25 A Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 16

Miscellaneous • Also need to recognise symbols for Switches, Grounds, Crystals etc, etc Switch SPST Antenna Switch DPST Fuse Earth Chelmsford Amateur Radio Society Intermediate Licence Course Chassis Lamp Murray Niman G 6 JYB Crystal Earphone Loudspeaker Microphone Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 17

Practicals • 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 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G 6 JYB Slide Set 3: v 1. 2 3 -May-2009 (3) Technical Basics -1: Components 18