Lab 1 report PDF

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Report for lab 1...

Description

Objectives The goal of this experiment was to get familiar with the proto-board, understand how to connect ICs, understand the logic behind each gate and to learn how to make a very simple circuit.

Introduction At the beginning, we are introduced to the proto-board. This device is equipped with power supplies, breadboards, switches, LEDs and so on that allow us to carry out this experiment. Using this board and integrated circuits, we can recreate the circuits we have seen and drawn in class and see their outputs in real time. Our knowledge of boolean algebra is essential for proving the correctness of the outputs we get and for understanding them.

Results Part 1 In this first part of the experiment, we use 4 different ICs, two of which are the same type. IC 7410 is a triple 3-input NAND gate which means it can accommodate up to three inputs and the result is an inverse AND. IC 7402 is a quad 2-input NOR gate which means it can accommodate up to two inputs and the result is an inverted OR. IC 7404 is a hex inverter which means it takes one input and the result is the inverse of that input. We start by placing the two 7410, the 7402 and the 7404 ICs onto the breadboard. Per the specifications of the experiment, we begin constructing our first logic switch, which connects to the pins 1, 2 and 13 of the first NAND gate (IC 7410) and the output leaves from pin 12. The second logic switch also uses a NAND gate. Pins 3 and 4 are connected to the 5 volt power supply while the logic switch connects to pin 5 and the output leaves from pin 6. The NOR gate (IC 7402) has a shared input connected to pins 8 and 9 and the output leaves from pin 10. The hex inverter (IC 7404) has one input connected to pin 1 and the output leaves from pin 2. Having set up these circuits, we can now test them and create truth tables out of the outputs we get. A

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Part 2 In this second part of the experiment, we use the same set up of the first part minus the additional 7410 IC and never forgetting to attach the 5 volt supply and the ground for each IC. The first logic switch is connects to the pins 1, 2 and 13 and the output leaves from pin 12. The hex inverter has one input at pin 1 and an output that leaves from pin 2. In this scenario, both outputs leaving from pin 12 of the NAND gate and pin 2 of the hex inverter connect as 2 inputs for the NOR gate at pins 8 and 9 respectively and the final output leaves from pin 10. The set up being done, we proceed to test for all possible combinations to obtain a truth table. A

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1. This circuit produces an AND boolean function. 2. The results here match the ones expected from the circuit. Input A is the only input going into the NAND gate

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which means it only inverts itself. Input B is going into a inverter which means it’s also inverting itself. A NOR gate will only have an outcome of 1 if both the inputs it receives are 0 and that is exactly what happens here.

3. We could get the same results by simply using a NOR gate for A and a NOR gate for B which would result in inverted results for each one and then passing those results as two separate outputs to a third NOR gate.

Part 3 In this third part of the experiment, we use only one 7400 IC for both NAND gates. We do the usual set up by connecting the IC to the 5 volt power supply and the ground. This IC takes two separate inputs A and B which connect at pins 1 and 2 respectively and has an output which leaves from pin 3. In order to reuse the same IC for the next step, we connect the output from pin 3 to the two inputs at pins 4 and 5 and the final output leaves from pin 6. We then proceed to test for all possible combinations to obtain a truth table.

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Questions: 1. This circuit produces an AND boolean function.

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2. The results here match the ones expected from the circuit.The first NAND gate will take the two inputs and them. The result of the first NAND gate will then go into

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the second NAND gate and being the only input, it will only invert itself as a final result. Looking closely at this logic we can see that it’s a simple AND gate.

3. Using NAND gates in design digital circuits is the preferred way to go because it is much cheaper to make only one gate than a couple of different ones and it can be used to build any of the other gates available and that’s why it is known as a universal gate.

Part 4

In this fourth and final part of the experiment, we use two AND gates (IC 7408), one OR gate (IC 7432) and a hex inverter (IC 7404). We do the usual set up by connecting each gate to the 5 volt power supply and the ground. The first AND gate takes two inputs connected at pins 1 and 2 and the second AND gate also takes two inputs connected at pins 10 and 9. The output of the first AND gate leaves from pin 3 and connects as input to the OR gates pin 1. The output of the second AND gate leaves from pin 8 and connects as input to the OR gates pin 2. The OR gate

takes those two inputs it receives and generates an output that leaves from pin 3. Finally, the output generated by the OR gate is connects as input to the hex inverters pin 1 and the inverter generated the final output that leaves from pin 2. Using an LED, we probe each internal node (x, y, z) and record the results in a truth table. A

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Questions 1. When debugging circuits there are many problems that could arise. One of the most common mistakes is forgetting to connect the power supply and the ground or connecting them in the wrong slots (this happened to me a few times during this experiment). Another problem would be connecting inputs and outputs wrong on an IC. Using damaged ICs is a problem that we are not too quick to see but it happens and we should pay attention to it (this also happened to me during this experiment). Connecting everything properly but forgetting to

turn on the proto-board could also be a problem or simply using a damaged proto-board could be a big problem on it’s own. Another possibility could be using more inputs than a gate can deal with.

Discussion This lab was very simple and straightforward as it should have been because it was simply an introduction to help us familiarize ourselves with the proto-board and it’s components. The results obtained in the lab and the ones produced by the truth tables in the pre-lab were a match. Whenever I obtained a result that did not match, I knew the board or the IC was the problem because my logic was correct and I was able to debug the problem by checking the ICs for faulty pins or any faulty jumper wires.

Conclusion In this lab, we learned how to use the proto-board, how to correctly place and wire up an IC with proper power and ground, how to make a circuit in more than one way and understand the logic behind it....