2.2.5.P Fireplace Control Circuit



?Project 2.2.5 Universal Gates and K-Mapping: Fireplace Control CircuitIntroductionThe Acme Fireplace Company has hired you to redesign the fireplace control circuit for their latest residential gas fireplace. The fireplace burner is equipped with four thermal sensors that output a logic (1) whenever a flame is present. These sensors are connected to the fireplace control circuit which outputs a (1) to the emergency cut-off valve to keep the gas flowing (i.e., a zero will turn the gas off).The original design of the fireplace control circuit was quite simple. For the gas valve to remain on, all four sensors needed to output a logic (1). During field testing it was discovered that variations in gas pressure and humidity cause the thermal sensors to occasionally output a logic (0) even when a flame was present. This caused frequent unnecessary shut downs and constant customer dissatisfaction.ABCDFireplaceControlCircuitGas LineEmergency Cut-Off ValveThermalSensors (4)ABCDFireplaceControlCircuitGas LineEmergency Cut-Off ValveThermalSensors (4)For the redesign, it has been determined that the emergency cut-off value should remain open as long as three of the four sensors indicate that a flame is present.Additionally, the designers have asked you to add a second output indicator to the control circuit. This indicator will output a logic (1) when the four sensors do not all agree (i.e., not all on or not all off). This indicator will be used by the service technician to diagnose whether a faulty sensor exists.Equipment Circuit Design Software (CDS)Breadboard (DLB or DMS)#22 Gauge solid wire Integrated Circuits (74LS00 & 74LS02)Procedure DesignDesign a combinational logic circuit that meets the above detailed design specifications.Additionally:The Karnaugh mapping technique must be used to obtain the simplified logic expression for both outputs.The circuit that controls the emergency cut-off valve must be implemented using only 74LS00 two-input NAND gates.The circuit for the possible faulty sensor indicator must be implemented using only 74LS02 two-input NOR gates.SimulationUsing the Circuit Design Software (CDS), enter and test your Fireplace Control Circuit design. Use switches for the inputs A, B, C, and D and a probe or LED circuit for the two outputs. Verify that the circuit is working as designed. If it is not, review your design work and circuit implementation to identify your mistake. Make any necessary corrections and retest. Be sure to document all changes in your engineering notebook/portfolio. PrototypingUsing a Digital Logic Board (DLB) or Digital MiniSystem (DMS), build and test your Fireplace Control Circuit design. Verify that the circuit is working as designed. If it is not, YOU SHOULD NOT CHANGE YOUR DESIGN. You know that your design functions because you simulated it. If your circuit isn’t working correctly, you must have built something incorrectly. Review your circuit implementation to identify your mistakes, make the necessary corrections, and retest. Be sure to document all changes in your engineering notebook/portfolio.ConclusionUsing your engineering notebook/portfolio as a guide, write a conclusion (minimum 250 words) that describes the process that you used to design, simulate, and build your Fireplace Control Circuit. This conclusion must include all of your design work (i.e., truth table, K-Maps, etc.), preliminary and final schematics, parts list, and a digital photograph of your final circuit. The documentation should be complete enough that a student with a similar knowledge of digital electronics could reproduce your design without any additional assistance.Elaborate Explanation23545802619375Figure. 10Figure. 1361188016192501659255203835016592551371600BC’+A’D+AB’+CD’ABD+ABC+BCD+ACD020000BC’+A’D+AB’+CD’ABD+ABC+BCD+ACD446913078105000190580010000In the “Activity 2.2.5 Fireplace Control Circuit”, I used many different techniques that helped me to reach the final product. Amazingly the design worked and it was true to the truth tables that I made before the design. First to the important things to do is to make a truth table for the Emergency Cutoff valve and the Faulty circuit Indicator. Like these:Next using those truth tables create the corresponding Un-simplified logic expressions.2040255126365006858012954000Once you have found the Un-simplified expressions, simplify them using the K-mapping technique.This technique can easily simplify expressions without using Boolean algebra or De Morgan’s Theorems.-30289528257500right92646500-22955256350Figure. 2, 30Figure. 2, 3And Now that you have the simplified Expressions (as seen in figure 1) you can go to the Circuit Design Software and prepare the circuit to test out. These are the Circuits that I got from those truth tables and k-maps. Once you have this get your breadboard ready and place your circuit there according to the schematic you made on cds. And the working end result should be: ................
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