Project Overview
For this project, we got into pairs and built a device from a Fischertechnik Kit, which we then hooked up to a board and designed a circuit so that the contraption would simulate a copying machine in the event of a jam. We went through the processes below to come to a final simplified expression, which we then built the circuit off of, and tested. Some constraints were that we had to use AOI logic, as well as a flip flop in our design. We also had to use an external power source to power the lights of the device.
Truth Table, Minterms and Un-simplified Expression
Boolean Algebra & Simplified Expression
K-map & Simplified Expression
Wiring Diagrams
The circuit was pretty easy to build on Multisim. I just used an example from a previous activity on flip flops to look at in order to make sure that I was doing it correctly. The combinational logic design itself was very simple; only 3 gates, and that is due to the easy problem we had to solve, which simplified to two minterms.
Explanation of Parts and Functions
- resistors are used to limit the current to prevent the lights from getting too hot; however, we did not use resistors, and our fingers didn't burn off
- the combinational logic circuit is used so that the buzzer and light will be activated when we want them to, so we create a truth table that we can then get a simplified expression from, which we will then use to put together a circuit with AOI logic gates on a simulator and test it
- the flip flop is needed because we want the light and buzzer to both turn on in the situation of a jam; however, we want the light to turn off right away and the buzzer to remain on until cleared, and the flip flop is the only way that we have learned to do this
- the LED goes off because when the readings of the phototransistors change, or the inputs of the combinational logic circuit, then the LED will not read the output that is needed for it to turn on, but the buzzer will stay on because it is attached to Q, which wants to be like D on the rising edge of the clock, and D is always on because it's connected to voltage; the only way to turn off the buzzer is to clear it, basically resetting the flip flop
Conclusion
This project was different from all other so far because we used the flip flop chip, that we have never used before, in a real-life application. We also had to build something in addition to creating the circuit that we would wire to the circuit as part of the design, in this case we used the Fischertechnik Kit to simulate the inside of a copier. In addition, we attached a buzzer to the board that made an unpleasant sound when it was activated. I learned how to incorporate other components into the circuit along with the board, such as the buzzer and the phototransistor setup, which acted in the place of switches. I also learned how a flip flop chip is set up, which is basically backwards from how it looks on MultiSim and very confusing, other than powering and grounding the chip. Finally, I learned how to use an external power source rather than the board itself to power something such as our phototransistors and lights.