In a power plant four heat sensitive gauges are used to monitor the temperature of four different parts of the machinery. The gauges are identified as Z,Y,X, and W and given the weighting 8, 4,2, and 1 respectively. When the temperature of an individual gauge reaches a dangerous level it output a logic 1; for all other conditions it outputs a logic 0. The output from the four gauges are combine to form a four bit binary word. When the combine weighting from the gauges reaches 9 the plant operator switches the machinery off ensuring that the combine weighting of the gauges never exceeds 9. Assume the change in temperature of the machinery follows the binary counting sequence. The binary word from the gauges forms the input to a combinational logic circuit, the output from which is connected to a seven segment LED display. Your job as a design engineer is to:-
1) Working in groups of three design the combinational circuit that is connected to the seven segment LED using logic gates or any other forms of small scale integration logic device and appropriate drivers for the LED. For this coursework you must not use a single off the shelf device. Students who take this approach will fail the exercise.
2) Prototype and test the circuit using breadboard
3) Design the PCB for the circuit using four switches to represent the gauges
4) Populate and test the PCB.
It is important that the characteristic of the devices are fully understood before using them in your design.
If the engineering labour rate is £45/hour and the manufacturing labour rate is £35/hour estimate how much it would cost to manufacture 1000 of the devices. What would the individual price per device be?
Write a report which outline the work undertaken, the difficulties encountered and the solutions applied to solve them. The report must not be more than 3 single side A4 pages. What is the more popular name for the circuit you have design?