Logic Probe Experiment PDF

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Summary

A report based on an experiment that is done in the course...

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Logic Probe Experiment Report

Drew Stickler ENGR 19600 – Introduction To Engineering October 11, 2018

Purpose The purpose of this experiment was to simulate, build, and test a circuit. This circuit uses multiple inverters to invert the direction of the current. Combined with a potentiometer, which acts as a variable voltage dividing resistor, we were able to turn one LED off while turning the other on.

Materials Required We used a variety of materials in order to complete the circuit such as: -

One solderless breadboard One 7404 hex inverter Two LEDs (light-emitting diode) Two signal diodes Resistors: One 2.0 kΩ & three 330 Ω One 1 kΩ potentiometer

Equipment Required The equipment that aided the simulation, testing, and build of the circuit are among these items: -

Multisim circuit simulation software Power source capable of outputting 5V or more Digital multimeter Oscilloscope

Circuit Schematic The circuit schematic aided us with putting our circuit together, as well as to retrace our circuit when we came across issues in our experiment.

Circuit Simulation With Multisim, we were able to simulate our circuit before we brought it to the breadboard. This simulation diagram was also used in the creation of our physical circuit.

We used the potentiometer to act as a variable voltage resistor. Depending on how we inverted the circuit, when we adjusted the voltage through potentiometer, this changes the voltage current running through our circuit. This in turn changes which LED is on at that time. Depending on how we inverted our circuit, would change which LED would turn on at certain voltage levels.

This simulated diagram shows the implementation of the first inverter. By connecting the potentiometer to the third prong of the 7404 hex inverter, and connecting the fourth prong to the diodes, we were able to flip the yellow and red LEDs.

This diagram shows the second inverter that was implemented into our circuit. When the LEDs are on, there is a voltage differential between, in this case the 5V power source, and the potentiometer. When this occurs, there is a flow of current running through the circuit, turning on the LEDs. In this experiment, we were able to change this between LEDs to switch one on while the other is off.

Circuit Build We used all of the materials required to create the circuit, and tested the voltage of the circuit at different settings of the potentiometer to get readings and better understand how the circuit is flowing current throughout the system.

Circuit Test We started with no inverters within the flow of current and measured the voltage at different points including LOW input, HIGH input, and OPEN input, and moved our way up to two inverters. Yellow (LED) Red (LED)

Input is LOW

Output Logic Level Input is OPEN

Input is HIGH

No inverter

Yellow: 0V - 0.82V

0.83V - 1.94V

Red: 1.95V - 4.95V

One inverter

Red: 2.91V - 1.91V

1.90V - 0.81V

Yellow: 0.80V - 0V

Two inverters

Yellow: 0V - 1.16V

1.17V - 1.36V

Red: 1.37V - 2.92V

We then measured the voltages with various test cases, measuring through pin three through six on the 7404 hex inverter. Input Logic Level (Pin 3)

Output Logic Level (Pin 4)

Logic Level (Pin 5)

Logic Level (Pin 6)

Vin momentarily on ground

0.01V

2.91V

2.91V

0.01V

Vin momentarily on +5.0V

-4.94V

-2.04V

-2.04V

-4.94V

Fault condition: open at pin 5

- 4.94V

-2.03V

-3.29V

-4.94V

Summary and Conclusion We first tested the circuit through the multisim circuit simulator. We then brought the experiment to the lab where we built and tested the circuit physically. As our experiment progressed, we made our measurements and recorded the results....