Electronics: Oscilloscope

Below is a picture of a cathode tube laid bare. This is what also goes on inside of an oscilloscope. The green dot that is shown there is an electron being shot through the tube.

Inside the tube, there are horizontal and vertical plates to guide that one electron to a certain position on the screen.

This is a close up of the tube with the electron.

An oscilloscope can track the electron and also manipulate it. As you can see, the electron is moving compared to the electron shown above that is stationary.

It can also have the electron go faster and faster until...

Only a straight line is visible.

First, we were asked to find the acceleration of the electron using the force equation based on charge and the F = ma equation. The variables that are fixed are charge, mass, and distance. The x-axis velocity is also found to be constant. We were then asked to find the voltage inside the tube.

This is a quick video of a wave generator connected to a speaker. When connected, we were able to hear the noise being generated as well.

This was our set up.

We first set the hertz to 0.096 kHz.

With our small tone emitter.

We also connected the wave generator to the oscilloscope to track the movement of the electron.

We can see slight movement. The whole thing was being powered by two batteries set in series.

A different wave form is being displayed on the oscilloscope.

When the wave generator was set at 96 Hz, we heard a deep low sound but when we set it to square waves, it became louder and sharper and in triangle wave, it sounded like the sine wave but louder. When we changed the frequency of the function generator output, the tone changed and it could go higher and lower depending on the setting. Also, the change in amplitude represents the pitch of the tone.

Sine waves:

Square waves:

Triangle waves:

When we played with the power/illumination controls, the electron became brighter or dimmer. The focus control makes sharpens the line. The most left knob manipulated the electron vertically, the middle knob did nothing, and the x-position knob manipulated the knob horizontally. When we played with the sensitivity controls, it made the electron change the divisions per voltage.

We determined the period of sinusoidal waves to be 10.4 ms. When calculated to find the Hz, it was the same as the one we had on input. The AC/DC setting did not do anything to the display of the oscilloscope. After playing with the frequency dial, multipliers and the time base control on the oscilloscope, the wavelengths were compressed and decompressed.

Unfortunately, our outlet source was a bad source.

Below are examples of DC and AC adaptors that we used in our lab.

With this circuitry, we were able to create Lissajous figures.

Below are both figures being shown. The circle is produced when the wave generator is set at 60 Hz and the more arrow looking figure is shown when the wave generator is set at 30 Hz or 120 Hz.

Next, we were given the Mystery Box challenge. We were asked to find the different relationships between each terminal.

Utilizing the oscilloscope to visually see the relationships, we were able to determine the circuitry inside the box.

The black terminal was the yellow terminal was not connected to anything. But the black terminal was found to be the ground terminal and was connected to everything else. No other terminals were connected to each other.

Circuits: Measuring Capacitance

"Hello, I am a capacitor," is what it would say.

Similarly to resistors, there is a parallel and series relationship when determining how much capacitance there is within a circuit. But, the relationship is the opposite of resistors. When capacitors are in parallel: C = C_1 + C_2 + ... C_n. When the capacitors are in series: C = 1 / (C_1 + C_2 + C_n).

We were then given a sample circuit and were first asked to find the total capacitance in the circuit. C_1 was 20 nF, C_2 was 50 nF, and C_3 was 40 nF. The first capacitor had 11 V stored in it. Utilizing this information, we found the total capacitance to be 52 nF. Secondly, we wer then asked to find the voltage of the second battery. We found the volts to be 18.3 V. Part D, we were asked to find the potential within this circuit.

The next few pictures are of a few different types of capacitors that were available in the lab.

This was the biggest out of the three and had the highest amount of capacitance.

We stored some energy within the capacitor and then created a circuit to light up a light bulb. And as you can see, it worked.

If the following circuit was being closed by a person, the person would feel 1.21 gigawatts! That is some incredible power. The current is shown to be flowing from the positive end of the battery to the negative end which is also charging the capacitor. When the battery is taken out of the circuit, the current will flow in the opposite direction because now, the capacitor acts like the battery.

The next few pictures are of the group measuring the volts within the capacitor.

We found a constant number to be at 3.54 V.

This was how we set the circuit up to charge and measure the capacitor.

This circuit was set up to measure the current and potential change within the capacitor that is connected to a resistor and an external energy source through Logger Pro.

This was the result that we got from the Logger Pro program.

The bubbles displayed the numerical relationship like slope. Through this exercise, we found that this certain equation had a power that is called the time constant: RC.

The highlighted numbers are the time constants.

Using letters A, B, and C to represent a general equation, we found that when the capacitor was charging, the equation is A(1-e^-Ct) and discharging equation is A*e^-Ct. We found the time constant for our lab to be about .37.

The following is a derivation to get the time constant equation. We started with the capacitor equation and the voltage equation, where I was also equal to the derivation of charge, Q. The time constant is also represented with the Greek letter tao.

We were then finally asked to find the current in terms of time with the equation we found through our experimentation.

Electronics: Analog and Digital Oscilloscopes

With an app downloaded on a phone which was then connected to an oscilloscope, we used it to visually see the sound waves emitted by the phone. At certain hertz, we were able to see the different types of waves that is emitted. As the hertz level was raised, the higher the peaks of the waves.

We now turned on a song to see what the oscilloscope would display and it displayed sharp and fast waves.

We then connected to the circuit the speaker to see if the speaker would emit the song.

Although the oscilloscope was displaying that the circuit was connected well, the speaker was not working properly. It may have been a circuit problem within the speaker or our wires were not connected properly.

Next, Professor Mason provided us with some bread boards and a red light bulb. He told us to build a circuit with a capacitor to light up the red light bulb.

The little holes are connected to each other in a column and with some extra circuit wires and an external battery, we were able to light up the red light bulb.

This is an overhead view of the circuit. We were also given a resistor to add the circuit.

The capacitor acts like an on and off button for this circuit.

This is the capacitor.

This is what we had to work with. The external energy source and speakers were connected but not turned on. The box contained the extra wiring we may have needed.

We tested the condition of our bread board by connecting it to the oscilloscope.

Something was being emitted..

This was the end result of our bread board.

At last, we connected it to the external energy source and speakers and as we pressed the capacitor button, the speakers were able to emit music with much difficulty.