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buyahyeh
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[Thread moved from a technical forum, so no Homework Template is shown]
A controller is required to monitor the natural illumination of a sports stadium and, when the ambient light is below a pre-set level, to switch on external lighting. The system is required to be of high integrity, and various monitoring indicators are to be incorporated as specified below. Furthermore, the status of the light (Large white LED) is to be monitored, and if this should fail, when the lighting should in fact be on, a warning signal is to be given in the form of a flashing orange LED.The circuit brief states: 1. A light dependent resistor (LDR) is to be used to determine ambient light levels. 2. A red light emitting diode (LED) should illuminate whenever the ambient light level is below the pre-set value. 3. A green LED should be illuminated if the ambient light is above the predetermined level. Note, the use of two LEDs in this manner serves to indicate that power is applied to the system, as one LED will always be on. 4. An orange LED is to flash on and off repeatedly, in the case that the ambient light level is low, and the white LED is not illuminated, i.e., it has failed. 5. Individual functional blocks of the circuit should be constructed using breadboard, and operation verified, before soldering the relevant components to circuit strip board. One example of such a component block may be the LDR and comparator light detection circuit.
Questions
1. Provide a block diagram of the complete lighting controller, and outline the functions of the different circuit blocks. State how the different blocks interlink. A scanned hand drawn diagram is acceptable.
2. Provide a circuit diagram of the circuit that you actually produced. State the basic principles of the method of operation.
3. Theinitialsectionofthecircuitincorporatesalightdependentresistor(LDR),apotentiometer and an operational amplifier (op-amp) to detect ambient light levels. State the manner in which this part of the circuit functions.
4.A thermistor could have been used to determine when the incandescent bulb was illuminated. State if you consider this to be a reliable system to sense correct operation of the bulb.
5. By what method, other than the incorporation of an LDR, could the operational state of the bulb be determined?
6. The original circuit specified the use of a NAND gate oscillator state the operating principles of this portion of the circuit and which component you used to satisfy this function.
7. The circuit as originally designed may have incorporated a time delay function to ensure correct operation of that part of the circuit intended to indicate that the incandescent light had failed. Why would the time delay be necessary?
8. All of the light emitting diodes (LEDs) in the circuit have a resistor in series. Why are these resistors necessary?
9. Suggest a method of improving operation of circuit
A controller is required to monitor the natural illumination of a sports stadium and, when the ambient light is below a pre-set level, to switch on external lighting. The system is required to be of high integrity, and various monitoring indicators are to be incorporated as specified below. Furthermore, the status of the light (Large white LED) is to be monitored, and if this should fail, when the lighting should in fact be on, a warning signal is to be given in the form of a flashing orange LED.The circuit brief states: 1. A light dependent resistor (LDR) is to be used to determine ambient light levels. 2. A red light emitting diode (LED) should illuminate whenever the ambient light level is below the pre-set value. 3. A green LED should be illuminated if the ambient light is above the predetermined level. Note, the use of two LEDs in this manner serves to indicate that power is applied to the system, as one LED will always be on. 4. An orange LED is to flash on and off repeatedly, in the case that the ambient light level is low, and the white LED is not illuminated, i.e., it has failed. 5. Individual functional blocks of the circuit should be constructed using breadboard, and operation verified, before soldering the relevant components to circuit strip board. One example of such a component block may be the LDR and comparator light detection circuit.
Questions
1. Provide a block diagram of the complete lighting controller, and outline the functions of the different circuit blocks. State how the different blocks interlink. A scanned hand drawn diagram is acceptable.
2. Provide a circuit diagram of the circuit that you actually produced. State the basic principles of the method of operation.
3. Theinitialsectionofthecircuitincorporatesalightdependentresistor(LDR),apotentiometer and an operational amplifier (op-amp) to detect ambient light levels. State the manner in which this part of the circuit functions.
4.A thermistor could have been used to determine when the incandescent bulb was illuminated. State if you consider this to be a reliable system to sense correct operation of the bulb.
5. By what method, other than the incorporation of an LDR, could the operational state of the bulb be determined?
6. The original circuit specified the use of a NAND gate oscillator state the operating principles of this portion of the circuit and which component you used to satisfy this function.
7. The circuit as originally designed may have incorporated a time delay function to ensure correct operation of that part of the circuit intended to indicate that the incandescent light had failed. Why would the time delay be necessary?
8. All of the light emitting diodes (LEDs) in the circuit have a resistor in series. Why are these resistors necessary?
9. Suggest a method of improving operation of circuit
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