Intermediate Course (3) Technical Basics - 1 Components Karl Davies East Kent Radio Society EKRS 1

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 2

Electrical Units QuantityUnitSymbol Voltage, VVoltVaka Potential Difference Current, IAmpA Resistance, ROhm  CapacitanceFaradF InductanceHenryH Power, PWattW Frequency, fHertzHz Wavelength, Metrem 3

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 4

Ohms Law Relates Voltage, VCurrent, IResistance, R V=I x RI=V/RR=V/I V Volts I Amps R Ohms 5

Power Relates Power, PVoltage, VCurrent, I P=V x IV=P/II=P/V P Watts V Volts I Amps 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   Cell   Battery + - 7

Resistors Fixed Resistors traditionally identified by Colour Code for Value & Tolerance Note that the modern BSI Symbol is preferred to the zigzag Resistor Variable Resistor Preset Resistor Potentiometer Note all the symbols opposite for the various forms Check Wattage Rating No 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% 9

Resistors in Series/Parallel Resistors in Series:- R total = R 1 + R 2 + R 3... 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 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 Pairs of coils can be used to create Transformers Transformer Inductor Iron-Cored Inductor 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 Capacitor Variable Capacitor Polarised Capacitor 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 Varicap Diodes Diode LED 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 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 c e b NPN Transistor s g d P-Channel Field Effect Transistor (FET) 14

Miscellaneous Also need to recognise symbols for Switches, Grounds, Crystals etc, etc Earth EarphoneLamp Chassis Crystal Antenna Microphone Loudspeaker Fuse Switch SPST Switch DPST 15

Practical Recognise Resistors by Colour Code Measure Resistors in Series Measure Resistors in Parallel Learn to Recognise other Components Soldering - correctly without damage 16