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S.G. Electronics

S.G. Electronics. Revision Lesson. Introduction. Electronic systems have 3 parts Input Process Output There are 2 types of systems: Analogue Digital. Output Devices. These turn E E into some other form Analogue Motor, Bulb, Loudspeaker Digital LED, Relay, Solenoid.

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S.G. Electronics

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  1. S.G. Electronics Revision Lesson David Smith

  2. Introduction • Electronic systems have 3 parts • Input • Process • Output • There are 2 types of systems: • Analogue • Digital David Smith

  3. Output Devices These turn EE into some other form Analogue Motor, Bulb, Loudspeaker Digital LED, Relay, Solenoid David Smith

  4. Input Devices • 2 main types • Change the size of the input voltage • Switch, Capacitor, • LDR, Thermistor • and David Smith

  5. Input Devices • Energy Changers • Thermocouple, Microphone • Solar Cell David Smith

  6. LDR • As Light Intensity Increases Resistance Decreases David Smith

  7. Thermistor • As Temperature increases the resistance decreases David Smith

  8. Capacitors • Store Charge • V • t • Provide timing delays David Smith

  9. Voltage Dividers Vs R1 Vout R2 0 V David Smith

  10. LDR in Voltage Divider • As light increases, resistance of LDR decreases, voltage across it decreases, V out David Smith

  11. Thermistor • As temperature decreases, resistance of thermistor increases,voltage across thermistor increases, V out decreases Vout David Smith

  12. Capacitor • Capacitor charges up • Vout increases V s V out David Smith

  13. Switches • When switch is closed • V out is low + 5 V V out David Smith

  14. Process Devices • Analogue : Amplifier • Digital : Transistor Logic Gates David Smith

  15. NPN Transistor • V be > 0.7 V • Transistor is switched on Collector Base Emitter David Smith

  16. Alarm Circuits • Light Intensity decreases • R ldr increases • V ldr increases • V be increases • V be > 0.7 V • Transistor switches on • Current flows through LED David Smith

  17. Alarm Circuits • Temperature increases • R thermistor decreases • V thermistor decreases • V resistor increases • V be increases • V be > 0.7 V • Transistor switches on • Current flows through LED • Current flows through LED David Smith

  18. Alarm Circuits • Capacitor charges up • Vc increases • Vbe increases • Vbe > 0.7 V transistor switches on • Current flows through LED • LED lights up • Closing switch discharges capacitor / resets system David Smith

  19. Logic Gates • Digital Devices • And Gate • Or Gate • Not Gate David Smith

  20. And Gate A B Output 0 0 1 1 0 0 0 1 0 1 1 1 David Smith

  21. Or Gate A B Output 0 0 0 1 0 1 0 1 1 1 1 1 David Smith

  22. Not Gate Input Output 0 1 1 0 David Smith

  23. Clock Pulse Generator • Capacitor charges up,Vc increases • Input to NOT changes from 0 to 1 • Output changes to 0 , (led on ) • Capacitor discharges,Vc decreases • Input to NOT changes from 1 to 0 • Output changes to 1, (led off ) • Process repeats David Smith

  24. Amplifiers • Analogue Process Device • Frequency unchanged V in V out David Smith

  25. Amplifiers • Amplifiers in CD players amplify power David Smith

  26. S.G. ELECTRONICS Now try the Revision Questions David Smith

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