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.
