Activity 3.1B – Basic Gates Application
Purpose
1. To be able to create a simple logic design from basic gates for given word problem.
2. To be able to simulate and test this logic design.
3. To be able to construct and test this logic design.
Equipment
Breadboard with jumper wires
5 volt Power Supply
IC chips: 7408 & 7432
LED and current limiting resistor
Logic switches
Computer Simulator
Procedure
Your uncle Lou owns a home heating and cooling company. Uncle Lou asks you to design a new automatic fan control unit for him to install in homes. He wants the fan to be ON under the following conditions….
The fan controller is in heater mode on AND the temperature is below 68 degrees OR fan controller is in air conditioning mode AND the temperature is above 75 degrees.
1. Using only two-input AND gates (7408) and two-input OR gates (7432) design a circuit that will satisfy these conditions. Sketch some ideas here:
2. Using a simulation tool, enter your design. Use logic switches for the four inputs heater mode, ac mode, temp 68, and temp 75 and a logic probe for the one output, fan.
3. Test your design by toggling the inputs. If your design does not work as expected make the necessary modification and re-test.
4. Record the conditions that caused the output (FAN) to be on. Put the results in the form of a truth table in the space here.
5. Print out your final design and label the input and output pins using the chip pin-out diagrams. Tape your final circuit design in the space provided.
6. Using a proto-board, construct your design. Be sure not to forget to connect both Vcc (5volts) and Ground to all your chips. Use switches for the four inputs and a LED for the one output. Don’t forget to use a current limiting resistor for the LED.
Before applying power show the circuit to your teacher and get signature:
______
7. Test your design by applying all possible inputs. If your design does not work as expected, you must have constructed the circuit improperly. (You know that you have a good design because you verified it with simulator.) Trouble shoot your circuit be checking all the wiring connections, chip pin-outs and Vcc/Ground connections. Make the necessary modifications and re-test.
8. Record the conditions that caused the output (FAN) to be on. Put the results in the form of a truth table and record that truth table in the space below.