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Chelmsford Amateur Radio Society Intermediate Course (3) Technical Basics - 1 Components Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3 (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 G6JYB Slide Set 3 (3) Technical Basics -1: Components 2 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 G6JYB Slide Set 3 (3) Technical Basics -1: Components 3 Unit Prefixes Factor trillionths billionths millionths thousandths thousands millions billions SN 10-12 10-9 10-6 10-3 103 106 109 Prefix pico nano micro milli kilo Mega Giga Examples: 25kV = 25000V 0.1uH = 100nH Chelmsford Amateur Radio Society Intermediate Licence Course Symbol p n or u m k M G 1500mA = 1.5A 2.45GHz=2450MHz Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 4 Ohms Law V Volts I Amps R Ohms Relates Voltage, V Current, I Resistance, R V=IxR I=V/R R=V/I Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 5 Power P Watts V Volts I Amps Relates Power, P Voltage, V P=VxI V=P/I I=P/V Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Current, I Slide Set 3 (3) Technical Basics -1: Components 6 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, NiCd, LiMH • Beware of Leakage, Shorts esp on Lead-Acid • Dispose of carefully Chelmsford Amateur Radio Society Intermediate Licence Course Cell + Battery Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 7 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 G6JYB Variable Resistor Slide Set 3 (3) Technical Basics -1: Components 8 Resistor Colour Code • First two Bands give Value Digits • Third Band is the Multiplier for Factor of Ten • Fourth Band is Tolerance • Example:- 12 x1000= 12k, 10% Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 9 Resistors in Series/Parallel • Resistors in Series:- Rtotal = R1+ R2+ R3 . . . R1 • R2 R3 Resistors in Parallel:- 1/Rtotal = 1/R1+1/R2+1/R3 . . . • For Identical Resistors this simplifies to... • For Two Resistors: Rtotal = R/2 R2 • For Three Resistors: Rtotal = R/3 R3 Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB R1 Slide Set 3 (3) Technical Basics -1: Components 10 Inductors & Transformers • Inductors are Coils which may be air or ferrite cored • Inductance is in Henries eg mH, nH, pH • Inductance is proportional to number of turns, diameter, core etc • Energy is stored in the magnetic field • They pass DC but increasingly block AC at higher frequencies • Inductor Iron-Cored Inductor Transformer Pairs of coils can be used to create Transformers Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 11 Capacitors • Capacitors are insulated plates, which can store electric charge • Larger plate areas, or smaller separation will give higher capacitance • Capacitance is in Farads eg uF, nF, pF • They block DC but increasingly pass AC at higher frequencies • Beware Voltage rating and polarity of Tantalum/Electrolytic versions • Note all the symbols opposite Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Capacitor Variable Capacitor Polarised Capacitor Slide Set 3 (3) Technical Basics -1: Components 12 Diodes • Diodes are PN Junctions 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 small forward Voltage Drop • LEDs - Light Emitting Diodes • Variable Capacitance Diodes - use PN Jn Capacitance • Zener Diodes - have a precise Reverse Voltage Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Diode LED Varicap Diodes Slide Set 3 (3) Technical Basics -1: Components 13 Transistors • • • Bipolar Transistors have NPN or PNP junctions Middle section is the ‘Base’. A small bias current can control a larger flow between Collector and Emitter b e NPN Transistor Current Flow is controlled Electrostatically in FET devices • Transistors can Amplify or Switch - or Oscillate • Integrated Circuits have arrays of Transistors on a single chip Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB c d g s P-Channel Field Effect Transistor (FET) Slide Set 3 (3) Technical Basics -1: Components 14 Miscellaneous • Also need to recognise symbols for Switches, Grounds, Crystals etc, etc Switch SPST Antenna Switch DPST Crystal Loudspeaker Fuse Earth Chelmsford Amateur Radio Society Intermediate Licence Course Chassis Lamp Murray Niman G6JYB Earphone Microphone Slide Set 3 (3) Technical Basics -1: Components 15 Practical • Recognise Resistors by Colour Code • Measure Resistors in Series • Measure Resistors in Parallel • Learn to Recognise other Components • Soldering - correctly without damage Chelmsford Amateur Radio Society Intermediate Licence Course Murray Niman G6JYB Slide Set 3 (3) Technical Basics -1: Components 16
