Fireplace Circuit
Problem
The problem was, well, a fireplace was not working how it was supposed to. There were a few things to be taken into consideration when redesigning this circuit. First off, there were four burners controlling the fireplace. The circuit was to be equipped with an emergency cutoff valve so that if less than three of the burners were active, the entire circuit would shut down. The second important thing to consider was that the circuit was to be equipped with an indicator, which would turn on if not all the burners were in agreeance. This means that if all four burners were not either on or off at the same time, the led would turn on. The final thing to consider was that the emergency cutoff valve had to be designed using NAND gates, while the sensor indicator had to be designed using NOR gates. Basically, the problem had to be approached taking it as two different circuits, which would then be combined to create one, fully functioning circuit.
Materials74ls02 (2 Input NOR IC)
74ls00 (2 Input NAND IC) Multisim CDS Digital Logic Board Simulation This step was very important to get right, because if I was lazy on this step, then that would mean that I would be wasting my time trying to create it on the digital logic board. However, both circuits went into the CDS just fine and worked how they were supposed to. Using the terms found from my K-Mapping, I was able to easily create a circuit. This step was fairly simple, because my circuits were already drawn on paper, so I simply had to copy them into the CDS. Although it was easy, it was very important to make sure that my circuit worked how it was supposed to, because if it didn't, I would have to check my design and see where something went wrong.
Digital Logic Board (Final Phase) Although it just looks like a huge web of wires, this is really a completed fireplace circuit! Now of course, it isn't actually a real fireplace, because we weren't supplied with tools to make fire, but if this were to be used as a fireplace circuit, it would indeed work. This step was time consuming, and took some planning and organization, but the satisfaction of seeing your circuit go from a design to a real thing is well worth the time put in. Basically, the four IC's lined up towards the top of the board (left in the first picture) are the NOR gates (Sensor Indicator), and the 5 towards the bottom half represent the NAND portion (emergency cutoff valve). Like I previously stated, I basically treated the circuit as two separate smaller circuits, and then combined them together to create one big functioning circuit that fit all of the design parameters. I started with the sensor indicator because it required less IC's, and then tested it to make sure that that half was working. Once it was, I moved onto the next portion, the emergency cutoff valve. Both circuits were plugged into different LED's on the board so that it could be visually seen that they were both working. The four switches represented the four different burners that could be doing different things at different times. To the right, I have attached a video showing the circuit in action.
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Designing the Circuit The first step in designing the circuit was to interpret the wording on our assignment sheet into real data that could be used in order for me to simulate the circuit. I did this by creating a truth table for each individual piece of thsi design, both the emergency cutoff valve and the sensor indicator. For the emergency valve, I basically just had to tell myself that anything with three or more zeroes would allow the fireplace to run, which would mean an output of 1. For the ones that had less than three running, I had to say it was an output of 0 meaning that the cutoff valve shut the circuit down. You could interpret this the opposite way, saying the cutoff valve turned on when there were less than 3, but this would not visually show up as well in the designed circuit or on the DLB later.
After making a truth table, I had to use that truth table to do some K-Mapping. Because of the way I designed the circuit, this step was very simple. The term I got from the emergency cutoff was ABC+ABD+BCD+ACD, and the term I got for the sensor indicator was ABCD + A(not) B(not) C(not) D(not). Both terms are very self explanatory if you take the problem statement into account. Basically, the emergency cutoff is showing all the different combinations that have three or more, which is exactly what the problem statement is asking for. The sensor indicator is saying that it will show when all four burners are not in agreeance. For this term, it basically is saying that it will change when it is not in that state. The last thing to do was to simply put the terms I found into a visual form. I designed the circuit in AOI first so that I could easily transform each circuit to their respective NAND/NOR forms. Once I finished the both the circuits, I checked for double inversions so I wasn't using any extra IC's than necessary. Conclusion Overall, it was nice to use the skills that I have acquired over this year to create a functioning circuit that can be actually be seen doing something in reality. This circuit was not just another useless thing that would never help anybody in life. Instead, it was a very possible, and feasible circuit that could actually be used. It was also nice to see the circuit sprout from a simple design all the way up to a physical thing that could be tested. Everything went very well for this project as well. This is most likely due to the fact that I took a lot of time on each piece of this project, and made sure that everything was working properly. Overall, this project was an excellent way to use the skills I've learned in class to create something useful.
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