1. 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

2. Solid state diode N P BARRIER REGION

3. Solid state diode N P BARRIER REGION

4. Solid state diode N P BARRIER REGION

5. Solid state diode

6. Junction transistor Transfer + Resistance = Transistor Made up of “sandwich” of PNP or NPN materials

7. Junction transistor N N P

8. emitter collector base Junction transistor

10. 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

11. Solid state devices Zener diode – allows output voltage to be fixed for use in power supply

12. Solid state –v- vacuum tube Solid state Efficient (little heat) Infinite lifespan Compact Physically rugged Low power ouput Low impedance Vacuum tube Requires and produces heat Finite lifespan Large Delicate High power output High impedance

13. Transistors

14. Printed circuit

16. Integrated circuit