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3. Foundation Course Technical Basics

3. Foundation Course Technical Basics. EKRS Karl Davies. Introduction. Important to appreciate and understand basic electric and radio frequency symbols, units and concepts You don’t need to be a circuit designer/builder!

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3. Foundation Course Technical Basics

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  1. 3. Foundation CourseTechnical Basics EKRS Karl Davies

  2. Introduction • Important to appreciate and understand basic electric and radio frequency symbols, units and concepts • You don’t need to be a circuit designer/builder! • that comes from experience and as you progress through the Intermediate and Advanced Courses • For Foundation it important to understand:- • Conductors and Insulators • Volts, Current, Power and Resistance • Frequencies and Wavelengths • Basic symbols/diagrams

  3. Conductors & Insulators • Conducts permit the flow of electric current • Examples: Copper, Brass etc • Metallic Conductors permit electrons to flow easily • 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 • Note that water is a conductor (esp. when impure), and that wet insulators can therefore conduct on their surface • This can be a risk for outdoor/portable equipment

  4. Electrical Units QuantityUnitSymbol Voltage, V Volt V Current, I Amp A Resistance, R Ohm  Power, P Watt W Frequency, f Hertz Hz Wavelength,  Metre m Note-1: Resistance is the opposition to current flow Note-2: Voltage is sometimes referred to as Potential Difference

  5. Unit Prefixes FactorPrefixSymbol millionths micro or u thousandths milli m thousands kilo k millions Mega M Examples: 4.7k=4700 1500mA = 1.5A 0.6MHz = 600kHz 500mW = 0.5W

  6. P Watts V Volts I Amps Power Relates Power, P Voltage, V Current, I P=VxI V=P/I I=P/V

  7. V Volts I Amps R Ohms Ohms Law Relates Voltage, V Current, I Resistance, R V=IxR I=V/R R=V/I

  8.  + - DC & AC Power DC - Direct Current • Cells/Batteries provide a source of DC power • Direct Current flows in a single direction • AC - Alternating Current • AC is easier to generate and transform • Mains is 50Hz AC. Radio Frequencies (RF) use High Frequency AC • Simple items such as Filament Light Bulbs work with AC and DC, but many electronic components are sensitive to the direction of current

  9. v vm/s Frequency, f fHertz metres Wavelength,  Frequency & Wavelength • In air the velocity, v of radio waves is a constant ( ~3x108m/s) • So if the frequency increases, the wavelength decreases, and vice versa, determined by: v = f x  • A 1MHz to 1000MHz conversion chart, and frequency allocation table is available

  10. Antenna Cell  Resistor  Switch SPST Loudspeaker + Crystal Fuse Battery -  Earth Lamp Microphone Circuit Symbols • Also need to recognise symbols for Switches, Earths, Crystals etc, etc SPST - single-pole, single-throw

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