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Solid state devices. Crystal diodes – a crystal and a bronze wire Semiconductors – made from poor conductors with conductive impurities Poor conductors = silicon and germanium Impurities = “P” substances with a shortage of electrons “N” substances with excess electrons. Solid state diode.
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Solid state devices • Crystal diodes – a crystal and a bronze wire • Semiconductors – made from poor conductors with conductive impurities • Poor conductors = silicon and germanium • Impurities = • “P” substances with a shortage of electrons • “N” substances with excess electrons
Solid state diode BARRIER REGION N P
Solid state diode BARRIER REGION N P
Solid state diode BARRIER REGION N P
Junction transistor • Transfer + Resistance = Transistor • Made up of “sandwich” of PNP or NPN materials
Junction transistor N P N
Junction transistor collector base emitter
Solid state devices • Junction transistor – “junction” refers to the junction between materials – where voltage appears. • Current amplifier (tubes are voltage amps) • Field effect transistor – “FET” is a low power high impedance device • Silicone controlled rectifier – “SCR” controls current flow – used in varispeed and dimmer
Solid state devices • Zener diode – allows output voltage to be fixed for use in power supply
Solid state –v- vacuum tube Solid state Vacuum tube Requires and produces heat Finite lifespan Large Delicate High power output High impedance • Efficient (little heat) • Infinite lifespan • Compact • Physically rugged • Low power ouput • Low impedance