Group 5 – Maria Bozzi, Brian Surber, Sifat Syed and Can Gurkan How Does it Work? It works with three sensors: the sight, the touch and the hearing It activates different lights or sounds an alarm if it sees or hears us, or if we touch it. The green light activates when these three sensors are off and when they don’t receive any input. The yellow light activates when one of these three sensors is stimulated. The red light means that two of three sensors are activated. The alarm rings when all of the three sensors are on. How Did We Work? We started to do the design of the circuit and we found the solution thanks to the Boolean algebra. TRUTH TABLE 0 0 0 0 0 0 1 0 1 0 0 1 1 3 1 0 0 4 1 0 1 5 1 1 0 6 1 1 1 7 1 2 How does the truth table works? 32 16 8 4 2 1 Now we sum the numbers that bring us to our solution, for example if we need the 0 we don’t need any of these numbers and in the Boolean algebra we write 000, if we need for example the 4 we need the third column and nothing else so we write 100, if we need the 13 we sum the fourth, the third, and the first column and we get to the 13 and in the Boolean algebra we write 1101… How can we apply the truth table to our circuit? Our truth table works only with two numbers, the one and the zero and in our circuits we need only the first three columns so we use the letter A, B, C. The zero corresponds to a normal A, B and C, and the one corresponds to the A̅, B̅, C̅. 0 0 0 A B C 0 0 1 A B C̅ 0 1 0 A B̅ C 0 1 1 A B̅ C̅ 1 0 0 A̅ B C 1 0 1 A̅ B C̅ 1 1 0 A̅ B̅ C 1 1 1 A̅ B̅ C̅ How can we apply the truth table to our circuit? Now that we know the correspondence between the numbers and the letters we can build our circuit, but HOW? There are two important gates in the circuits that we have to consider firstly, the AND gate and the OR gate. An AND gate corresponds to a (*) An OR gate corresponds to a (+) Our ABC, or ABC̅ corresponds to do A * B * C. So this means that between our three numbers there will be and gates. But what these letters – numbers represent? How can we apply the truth table to our circuit? A,B and C represents our three sensors in our circuit. The one is representing the sensor that is ON, the 0 represents that the sensor is OFF and the bar on the letter represent that we have to use the invertor. So we can copy our truth table to understand the sensors and how they can work. 0 0 0 A̅ B̅ C̅ 0 0 1 Ā B̄ C 0 1 0 Ā B C̄ 0 1 1 Ā B C 1 0 0 A B̄ C̄ 1 0 1 A B̄ C 1 1 0 A B C̄ 1 1 1 A B C How can we apply the truth table to our circuit? So in conclusion we can tell that the first row corresponds to our green light, the second, the third and the fifth to our yellow light, the fourth, the sixth and the seventh to our red light and the last one to our alarm. So we put our and gates between the letters and or gates between the blocks of letter that we use for a LED and the invertors in the sensor of the bar. Design of our circuit –yellow LED Invertor And gate Or gate YELLOW LED Battery Switches We have to put into the letters that represent the 001, the 010, and the 100 Design of our circuit – red LED Battery Invertor And gate Or gate RED LED Switches We have to put the letters that represent the 011, the 101, and the 110 Here we put also the alarm and the green LED and we simplified the yellow one We said to our circuit put the yellow light when the other lights are off For the alarm we need the ABC, that is the 111 and for the green LED the ĀB̄C̄ that is the 000 Then we applied our design to a real circuit Now you can take a look at our project working!!!