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Bredhurst Receiving and Transmitting Society

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Learning outcomes part 8

  • diode will conduct electrons only in one direction (forward bias).

  • A small forward potential difference is needed to turn the diode on.

  • a diode can bec used to produce direct current from the alternating current leaving a transformer (rectification).

  • Recognise the AC and rectified (pulsed DC) waveforms.

  • a capacitor can be used to store a charge during the non-conducting part of the cycle to provide a smoothing effect, and hence smooth DC.

  • Be able to recognise the waveform of smoothing effect.

  • a light emitting diode (LED) is made from a material that will produce light when passing a suitable direct current.

  • a variable capacitance diode behaves like a capacitor and that the capacitance can be varied by changing the applied potential difference.

  • a transistor (npn) can be used as an amplifier.

  • a small base current on the transistor will control a larger collector current and that this is the basis of amplification.

  • if the base current is large enough, the transistor behaves as a switch such that the current in the collector can be turned on and off.

  • a transistor can be used as an oscillator to generate audio and radio frequencies.

  • distinguish between a crystal oscillator and a variable frequency oscillator (VFO) based on a tuned circuit.

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