1. Introduction This is a lesson, relevant to Circuit Designing. Here I have tried to give a simple idea on, how to design a circuit. Try to understand the concepts. In the 1 st slide I have given steps of circuit designing. See every Slide with a good understanding of those steps. Next To explain this lesson, I have got an example of Road crossing system. This is only one side of circuit designing.

2. Practical Side Of Circuit Designing 1.Identify the requirements. (Think how it should happen/ work ?) 1.According to variables, prepare a truth table. 2.Write the sum of min terms. 3.Simplify it using K-Map method. 4.According to the expression draw the circuit. 5.Select the suitable IC which has necessary gates. 6.Build the circuit. PreviousNext

3. One usage is circuit designing for road crossing. See the Animated picture of a road crossing system and requirements. Then you will see how is the circuit designed ?. PreviousNext Practical Side Of Circuit Designing

4. A B C D N PreviousNext

5. 1 Requirements Above picture shows the intersection of a main highway with a secondary access road.Vehicle detection censers are placed along lanes C & D (Main road) & lanes A & B (access road). These censor outputs are low (0) When no vehicle is present & high (1) when vehicle is present. The intersection traffic light is to be controlled according to the following logic. 1. The East-West (E-W) traffic lights will be green when ever both lanes C & D are occupied. 2. E-W lights will be green when ever either C & D is occupied but lanes A & B are not both occupied. 3. The North-South (N-S) lights will be green when ever both lanes A & B are occupied but C & D are not both occupied. 4.The N-S lights will also be green when either A or B is occupied while C & D are both vacant. 5.The E-W lights will be green when no vehicles are present. Using the censor out puts A,B,C,D as input, design a logic circuit to control traffic lights. There should be two out puts N-S & E-W, that go high when corresponding light is to be green. PreviousNext

6. 2 Truth Table Censors Out Puts ABCDE-WN-S 000010 000110 001010 001110 010001 010110 011010 011110 100001 100110 101010 101110 110001 110101 111001 111110 PreviousNext E-W Min terms N-S Min terms

7. Sum Of Min Terms For E-W ABCD+ABCD+ABCD+ABCD+ABCD+ABCD+ABCD+ABCD+ABCD+ABCD+ABCD For N-S ABCD+ABCD+ABCD+ABCD+ABCD PreviousNext

8. Simplifying Min Terms Using K-map Here it is easy it design a circuit for N-S side. Because that min term is very simple. So it has a small circuit. Other case is, E-W = N-S Because while one side indicates red light, the other side indicates the green light. ABCD+ABCD+ABCD+ABCD+ABCD PreviousNext 0000 1000 1101 1000 AB CD

9. Expression & Circuit For N-S F = CD (A+B) + AB (C+D) E-W out put N-S out put A B C D CENSORSCENSORS PreviousNext

10. Selecting The Suitable Gates The gates, that is used in circuits are in ICs. They can’t be found as separate parts. If we want to use this gates in a circuit, we have to find the correct IC that contain those particular gates. (Using an IC manual) Eg: NEC 7853C PreviousNext 1 7 814

11. Build A Circuit Using ICs Here, you can see a circuit and how to make it using an IC. Circuit A B C X 1 7 814 ACB X PreviousNext

12. A B C D PreviousNext A B C D

13. Practical Side Of Circuit Designing 1 7 814 NEC 8572C Designed By Sandruwan PreviousPress Esc