5/5 Electronics

Lab Day 5/5/2015: Electronics

Purpose: In our experiments we will use different electronics to measure and visualize voltage changes. In particular we will focus on using oscilloscopes in order to see voltage changes and use a simple amplifier to look at how analog electronics are used as a conversion to boost a weak signal into a sound we can hear. Therefore we could break down different wave forms in order to solve the signals produced in the mystery box.

Oscilloscope: Basic Overview

We started class by learning how to use an oscilloscope which is a simple electronic device used to measure constant and changing voltages in respect to time through a cathode ray tube. The oscilloscope displayed shows different functions and we can use these controls to change the supply of power, the intensity, time/div, and others in order to measure the voltage from a source. For example we can make it brighter and dimmer using the intensity control and cause a voltage jump by changing the power using the illumination control. 

Cathode Ray tube electron analysis

Next, in a cathode ray tube we can use the second pair of plates to measure a sweep voltage which allows us to determine the voltage change vs time. We observe a saw tooth pattern that shows the potential as it varies with time. Therefore we can see that the speed in which the electrons move can be adjusted using the time/base control

If we apply a 1.2 voltage to the oscilloscope we can see a jump in voltage in the digital screen which is determined by counting the lines from the initial to final based off the settings of the increments to find the potential difference. 

We used the two plates of the CRT to calculate the symbolic relationship of the vertical component velocity of an electron and the voltage. The force of the electron is found in terms of charge q and the electric field which allow us to determine the acceleration as the electron passes through the two plates. Time was found as the length of the plates over the horizontal component of velocity. Finally, knowing that the electrons moving will travel in a type of parabolic motion similar to a projectile, we can find the final vertical velocity of that electron in terms of voltage. We observe that the final velocity is proportional to voltage.

We went further to find the change in the vertical distance y which was found using the projectile equation where we know that there is no initial velocity in the y component and it is again found to be directly proportional to voltage.

Activity: Measuring Changing Voltages

Function generator connected to an oscilloscope

AC offset

As we supply an AC generated wave into the oscilloscope, we see that it gives a sinusoidal wave form which shows variations. 

DC offset created a steady straight line.

Increasing frequency in square mode caused the lines to be shorter and decreasing frequency caused the lines to be longer. 

Experiment: Mystery Box

We were able to identify the voltage supplied from the mystery box through the different connections using the different wires and the signals that each displayed on the oscilloscope. The shapes are indicated below and the hertz is also shown in the pictures.