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Electronics General Revision

Electronics General Revision. Digital Outputs. off or on 0 or 1 0V or 6V. Electronic Systems. An electronic system can be described as having 3 parts, an input , a process and an output. input. process. output. The input starts the system working.

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Electronics General Revision

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  1. Electronics General Revision

  2. Digital Outputs off or on 0 or 1 0V or 6V

  3. Electronic Systems • An electronic system can be described as having 3 parts, an input, a process and an output. input process output • The input starts the system working. • The process changes the input or makes a decision. • The output gives us what we want from the system. • For a public address system these three parts would be as follows microphone amplifier loudspeaker

  4. Electronic Systems • An electronic system can be described as having 3 parts, an input, a process and an output. input process output • The input device changes a form of energy into electrical energy. • The process device changes the electrical signal in some way. • The output device changes electrical energy into another form of energy.

  5. Input Devices

  6. LDR Light Up Resistance Down LURD

  7. The Thermistor Temperature Up Resistance Down TURD

  8. Light –Emitting Diodes: Output Devices • This is the symbol for an LED Electron flow • An LED only allows electrons to flow in one direction

  9. Device Analogue/Digital Output Energy Buzzer Digital Sound Loudspeaker Analogue Sound LED Digital Light Lamp Analogue/Digital Light Motor Analogue Kinetic Output Devices In each case the main energy change is from electrical to some other form:

  10. Light –Emitting Diodes: Output Devices series resistor value? • If 2V across LED, then 3V across resistor. • 10mA through resistor • V=IR, R = V/I • R = 3/0.01 = 300Ω 2V across LED 10mA through circuit

  11. Logic Problems

  12. The NOT gate - inverter

  13. The AND gate

  14. The OR gate

  15. Water Sprayer • The gardener wants water to be sprayed onto plants if the air becomes too hot OR if the gardener switches the sprayer on. 0 = off 1 = on • What is the name of the logic gate? • OR

  16. Water Sprayer • The gardener wants water to be sprayed onto plants if the air becomes too hot OR if the gardener switches the sprayer on. 0 = off 1 = on • What input device could be used as a heat sensor? • Thermistor

  17. Water Sprayer • The gardener wants water to be sprayed onto plants if the air becomes too hot OR if the gardener switches the sprayer on. 0 = off 1 = on • Construct a truth table to find out under what conditions the sprayer will come on.

  18. Water Sprayer • The gardener wants water to be sprayed onto plants if the air becomes too hot OR if the gardener switches the sprayer on. 0 = off 1 = on • Construct a truth table to find out under what conditions the sprayer will come on. Input A Input B Output at Sprayer 1 1 1 0 1 1 1 0 1 0 0 0

  19. Water Sprayer For sprayer to be ON, either it gets hot OR the gardener turns it on OR, both. • The gardener wants water to be sprayed onto plants if the air becomes too hot OR if the gardener switches the sprayer on. 0 = off 1 = on • Construct a truth table to find out under what conditions the sprayer will come on. Input A Input B Output at Sprayer 1 1 1 0 1 1 1 0 1 0 0 0

  20. 0 = dark 1 = light Stair light switch • An old person needs the stair light switched on when it gets dark. He needs to be able to switch it on himself also. 0 = off 1 = on • What are the names of the logic gates? • NOT and OR

  21. 0 = dark 1 = light Stair light switch • An old person needs the stair light switched on when it gets dark. He needs to be able to switch it on himself also. 0 = off 1 = on • What input device could be used as a light sensor? • LDR

  22. 0 = dark 1 = light Stair light switch A B C • An old person needs the stair light switched on when it gets dark. He needs to be able to switch it on himself also. 0 = off 1 = on • Construct a truth table to find out under what conditions the sprayer will come on.

  23. 0 = dark 1 = light Stair light switch A B C • An old person needs the stair light switched on when it gets dark. He needs to be able to switch it on himself also. 0 = off 1 = on • Construct a truth table to find out under what conditions the sprayer will come on. For light to be ON, either it gets dark OR the person turns it on OR, both. A B C Lamp 1 0 1 1 0 1 1 1 1 0 0 0 0 1 0 1

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