Building an Oscilloscope from an Old CRT TV: [Essay Example], 5018 words (2024)

For my Capstone Project, I will be making an oscilloscope out of an old Cathode Ray tube TV. Producing a way to alternate the different waves so that the electrons can visually be seen on the TV is my top priority. I’ve always been interested in electronics. Doing this project will expose me to the unseen motions of electrons and show how they move with different capacitor frequencies. The usage of trying to incorporate different potentiometers as well as oscillators to make different variable sounds will be experimented with. This has been done by researching transistors and testing how they create the Reverse Avalanche effect to make a looping noise. Sound coming from the frequency sound generator would then be displayed on the oscilloscope, which would test the transistor’s theory. Reasons for me dabbling with this form of electricity include simply studying electronic motions in an intriguing way in which I can manipulate waves with sound variants. This will be a project of self-research which will help me for when I study electrical engineering. Though we may never physically see electrons moving with our eyes, this project will allow me visually to see electronic voltage signals instantaneously. In this research paper I will explore many types of electrical components and discover how to wire them to work together to enhance my oscilloscope.

To display my findings and research, I have two main headings which have multiple subheadings. I organized my paper into separate paragraphs based on different ideas and findings. Each paragraph pertains to a certain individual aspect of the project. This essay also includes four paragraphs right before the conclusion talking about my failures, struggles, and successes.

RESEARCH CONTENT

I got my inspiration from a YouTube series called, Look Mum No Computer by Sam Battle. I used what I learned from him and applied it to other things I was building. I ended up changing his oscillator plan by making my own oscilloscope and discovering how to implement oscillators to render better wave displays. He taught me about reverse avalanche sound effects and how they are used to create the oscillating loop noises. Pertaining to oscillators, transistors are used with 3 pins, but with reverse avalanche taking place, the middle pin is not in use. In order to obtain the reverse avalanche effect, you need a certain voltage high enough to get the transistor to oscillate. In some cases like in, Look Mum No Computer, Sam discusses on his channel what different transistors he tried. He even listed a source he found and used by Kerry D. Wong and then Sam mentioned how, “…the one that caught my eye and i may have to try is SS9018 as it is only needs 8 volts insteat of the aboves 12 volts!!! so im going to give this a go also.” This quote explains a segment of my research on how oscillators work and how they can be seen while being projected on an oscilloscope. He also basically states that playing with different capacitor values will alter the oscillating pitch. For instance, the larger the capacitor value is, the oscillating of it will be impedingly slow. When the capacitor valve is low, the pitch will be high and therefore will oscillate faster. Look Mum No Computer, also inspired me with insight to what it takes to create the perfect scale for operating different capacitor ranges. Sam goes into detail and explains the oscillating speed as such, “bass skulls: 100uF capacitor tenor skull: 33uF capacitor alto skull: 10uF capacitor”. The knowledge viewed from these videos inspired weeks of research, which led me to truly experience the different values of capacitors and their impacts on such sounds. This source of information is very vital to my project. Further research from Sam Battle’s YouTube Channel and personal website guide me to start ideating as to what my electrical specs may look like.

Making a battle plan, no pun intended, was my next step. First, the battery will be connected to a resistor, then hooked up to the potentiometer, which is 10K. The 10K potentiometer will then be hooked up to the capacitor, which will have a varying uF unit. Then, it’s hooked up to a transistor, which may vary from each individual oscillator set up. Lastly, it will be hooked up to another resistor which eventually connects to audio out. Also, the capacitor will be hooked up as well as the other side of the transistor to an LED to indicate it is a working circuit, which is then hooked up to ground. Keeping the transistor in mind, the middle leg out of the 3 pins will not be in use and might even be chipped off for more ability to oscillate better for the Reverse Avalanche effect. Lastly, this YouTube Channel and Battle’s website, helped teach me some of the most important aspects for the oscillating part of my Capstone Project.

Oscilloscopes and How They Work. Next, after exploring the book entitled, Electricity and Electronics, by Gerrish / Dugger / Roberts, I found it too contained worthwhile information pertaining to oscilloscopes and more technical aspects of how they work. Here in this source, I discovered the actual definition of an oscilloscope. It is quoted as saying, “A cathode-ray tube (CRT) is used in an oscilloscope. It consists of a cathode that emits a beam of electrons that strike a luminescent display screen” (Gerrish et al 153). Deflection coils are defined as such, “The vertical deflection plates and horizontal deflection plates control where the beam hits the display screen” (Gerrish et al 153). The previous quote explains the key components that I will be learning and dealing with in my Capstone Project. Though Cathode Ray Tubes are very antiquated in our modern world due to more efficient resolution TV’s, I figured it would be very captivating and beneficial to my self-education to explore in rather “simpler” forms of electricity, though still complex. I really want to study electronics and electrical engineering when I get older and when I’m in college. Studying simpler, outdated technology will be baby steps all involved in the series of actions taken to help me understand more complex technology. This is the purpose of the Capstone Project, to use current skills and to further research applied skills, to compose a project that will ultimately add to the CSI learning experience. Furthermore, page 152 of Electricity and Electronics is wonderful for explaining how I can understand oscilloscopes. It professes:

If an AC voltage is applied to the scope, the vertical deflection circuit controls the vertical deflection plate magnetic intensity. The vertical plate causes the beam of electrons to produce a wave of light on the display screen that is like the amplitude of the input voltage. This wave represents the instanteous voltage during the cycles of the AC input. The horizontal sweep oscillator can be adjusted through a wide range of frequencies until it matches the frequency of the input voltage (Gerrish et al 152).

The luminescent screen shows how amplitude effects the height and how the period represents the width. Sine waves are usually the first wave types you see in oscilloscopes. We learned about Sine, Cosine and Tangent in Precalculus. So, I perceive this project to be very appropriate and beneficial to studying mathematical graphing which is especially useful in college. The compiled works of Gerrish, Dugger and Roberts in this book source also taught me about OHM’s Law and the Watts Law formulas. I will be using these mathematical formulas to explore and test the accuracy of the oscillators and the oscilloscope put together. This book also demonstrates how Watt is the unit of the power shown. This is important to my project because if too much power is being displayed, it will be displayed on the luminescent screen as a bright circular light beam near the center of the TV.

Dangers of TV Brightness. The affirmation for how strong the magnetic intensity is during this time was stated in Electricity and Electronics. I am trying to learn how to prevent this from occurring. This is why the varying potentiometer resistors will be used for the safety of this project. Electricity and Electronics explains that “Focus is used to make the wave appear sharper. It eliminates any fuzzy appearance the wave may have” (Gerrish et al 155). So, I will experiment with different controls. I will solder to work on the clarity of the sound waves being shown on the oscilloscope. Intensity is a word I also studied in this book, along with focus, which can both kill your display screen. This book also instructs the reader that settings should always be turned on low before turning on devices so the brightness and intensity can be comfortably viewed. When viewing the graph output from the audio input waves, I will be observing them with the knowledge of how amplitude works. I reviewed what peak to peak means on a sine graph and also learned how to read what amplitude looks like on the graph. This can be documented through videos as proof of the execution, of which I will be taking later in the process as testing proof and maybe take slow motion film that will be used for clarification of the graph’s readings. This testing data will be taken without the store bought premade data acquisition and transfer application that usually comes with store bought oscilloscopes that properly view data that is produced.

Transistors Capabilities. Studying deeper into the nitty gritty miniscule, yet so vital aspects of this project, I checked out another book called Tab Electronics Guide to Understanding Electricity and Electronics By G. Randy Slone. Using transistors is important, but understanding them is even better. On page 155 the author writes, “A transistor is a solid-state, three-layer semiconductor device… Note that a diode contains only one junction, whereas a transistor contains two junctions” (G. Randy Slone). Knowing that bipolar transistors have an emitter, base and a lead point, will help me to correctly identify the correct placement of my transistors when using them.

Welding. Pursuing this further, the third book that I used for research was called Electromechanical Design Handbook by Ronald A. Walsh. Referencing page 526, it discusses the various forms of all things I currently have dabbled with for almost 2 years pertaining to my welding experience. I wanted to work on the craftsmanship of this project to make it look as professional as possible. To make this craftsmanship aspect of my project happen, I practiced stainless steel welding to see if I could weld a proper professional box to safely enclose my tablet. I figured this would work and would add a nice, polished touch to my project. For this to occur, I would use TIG which is known as Tungsten Inert Gas or GTAW. I may also practice welding with aluminum as well to see which one is best for my project and most durable for when the time comes. Gas Tungsten Arc welding can also be used with welding aluminum. To construct the box, I will be using the outside corner joint position and potential filler rod to fuse the metal, “Welding is a fusion process for joining metals” (Ronald A. Walsh 526). This gives the basic purpose of using welding in this process. If done correctly, my weld will be the strongest part or foundation of the welded box. On the same note similar to welding, I used a 60% tin - 40% lead solder for the manufacturing / industrial build layout process of this project. This composition will protect the electrical components at all cost depending on the type of metal used. Carrying out this process would look very professional to my project. However, I ran into some impediments in the welding lab. The TIG booths were all being used due to the welding certifications and performance tests being taken. I could use MIG (Metal Inert Gas) to weld up a box, but it would consist of steel that isn't protected and prone to rust overtime. Due to this restraint, I will try my hardest to get all my duties done in welding class first so I can try to get a box built. If resources like the Tungsten Rod are not available in the welding lab, which there is a shortage of, I won't be able to get this box done. I may have to resort to making a wooden box, which will still look very professional with craftsmanship.

Components and What They Do. Learning the individual aspects will help me actually understand how my project will work. Electroluminescence, which means to emit light, is what I'll be using in order to give an indicator as to its working. Resistors have colored bands that notify and label the resistance levels and tell how precise the resistance value is with its last band color. Resistors do not carry polarity like LEDs, capacitors, batteries and other components. Resistors are measured in ohms. Potentiometers are also like resistors but they are mechanically changeable. The ones I'm using for my Capstone Project consist of 10K 16 mm potentiometers. As mentioned in the www. Britainncia.com oscillators online encyclopedia, the electrical device produces current that is electrically alternating in tuned circuits which can then amplify depending on variance.

Potentiometers and Resistors. In The Maker’s Manual, by Andrea Maietta and Paolo Aliverti, it discusses “The two possible ways of using a potentiometer” (133). It explains how the three pins can either be connected to three totally different slots or the middle pin can be hooked up to the other pin’s legs that way you can cement your manually set resistance value without it being tampered with. In my case, I will connect all three legs to different slots so that the user can manipulate the different inputs into the oscilloscope. The component I will be using is called a variable resistor, while the lock method is called a voltage divider. You could use a regular knob variable potentiometer or what is called a trimmer, which kind of looks like a potentiometer but only has two legs and a screw like function. This serves as a voltage divider which contains a consistent resistant measurement unless actively changed.

Capacitor Danger and How to Discharge a CRT TV. While I will be using some different types of resistors, I will also be using different measurements of capacitors. This way it diminishes disturbances that are unwanted. Capacitors wind up working like sandwiches that make the current have a super hard time getting out and being used. When the capacitor is hooked up in a circuit, it is basically getting charged. So when the capacitor is in use, the power coming out of it is alternating, depending on how you place a capacitor. Also, when a power supply like a battery is removed from a circuit, and the capacitor makes a complete closed circuit, the load will be utilized for a short period during this time where the saved capacitor energy is being depleted. Regarding depleted energy, in order to work with an old Cathode Ray tube television, I will need to safely deplete the stored energy in the TV. It is very important that I drain the energy from the TV first before I further start to tinker with the vertical and horizontal Cathode Ray tube coil wires. To do so, I will crack the plastic shell of the TV located in the back. There you will find a small, circle, rubber disk which will need to be disconnected in order to drain and to deplete the saved-up energy from the TV capacitors. To accomplish this, I will take a screwdriver and wrap copper around the metal part and feed a wire to the metal frame or another safe metal part to allow the electricity to flow through it without tapping into me or the electrical components. This copper wire setup will allow me to pick away under the black circle flap until a few popping noises are heard. The popping noises mean the TV should be safe now. I know there are other factors to also consider.

Dangers of Tesla Coil Variants in TV. One of the main components that belong in the Cathode Ray tube TV is a variant of the Tesla coil. I really tried to research some of the key components for safety and readiness. Understanding the danger of these components is truly necessary to which I have found out by reading through Gordon McComb’s Gadgeteer’s Goldmine!, by Gordon McComb. Gordon McComb writes, “A form of the Tesla coil is used in television sets to create high- frequency high voltage for operating the Cathode Ray tube” (57). While researching the guts of the older style TVs, I realize now know how the picture shows up on the TV. Research has helped me understand that there are two coils inside a CRT TV. One coil acts as the horizontal display, while the other coil acts as the vertical display. Located here is where you find the wire layout as to where the wires hook up. Here is where you check the continuity to see which out of the four wires goes with each other. Keeping this backbone knowledge in my head, I researched the dangers of the Tesla Coil. The TV I will be working with contains variable strands of them. Tesla Coils have a gap which allows the capacitor to discharge at times at the intervals it's supposed tobe at. By doing firm research, I found out that this gap is what allows the horizontal and vertical beams to take the spark and funnel it into a rather precise clean-cut line by a magnetic field. Growing up, I always heard my parents say to me not to sit so close to the TV. I often wondered about this and decided to research reasons in carrying out this in my project. Tesla coils must be used in a well-ventilated room according to Gordon McComb where he states:

The open spark gap produces ultraviolet light, which can be extremely damaging to the eyes. Avoid looking at the spark gap, and if possible, enclose the spark gap in an opaque enclosure. The spark gap needs air to operate properly, so make sure the enclosure has holes for air to enter and escape. In addition, the sparking action produces toxic ozone. Use the Tesla coil only in a well-ventilated room (Gordon McComb 60).

Through testing procedures, I may use my welding helmet for ultra-protection during testing with the Tesla coil mechanisms in the CRT TV. These are very important facts that helped me conclude the safety risks I will come across during my project.

FAILURES, STRUGGLES AND SUCCESS

With any project there will always be successes and failures. Although failure is seen as not an option in today's society, I feel that as long as we grow from our failures that they can be used to teach us. Disappointment and failures spawned from this project without a doubt, but that didn't stop me. Multiple people told me I couldn't do this project and my response was 'watch me'. Here's my story: right off the bat, I have no knowledge of anything I attempted in this project. I walked into this Capstone Project nearly blinded by my own passion. I knew nothing about oscilloscopes or oscillators. All I knew about this topic was that they were mesmerizing to watch and play with. This is something that has always interested me and I've always wanted to render one. These can be used to make electronic music, which is another one of my passions: listening to electronic music. The research proportion was the best part to work on and was even more advanced than I had expected. This was all very foreign to me. The research began when I went to the library and hoarded nearly all of the electrical section of their books. Not knowing where to even begin with this project I drove straight into studying oscilloscopes first and documented my findings by taking notes. I went to my favorite place ever to study and that was at the bowling alley when my dad was bowling on his league. I popped on my electronic music on my headphones and that was one of the main fuels that guided me through this project with motivation. All I remember was being at peace while I was in the zone of weeks of research and ideating. Reality hit me when I drove into building my project.

Struggles. Building the oscilloscope from an old CRT TV went relatively pretty smooth because I didn't fry myself while playing in there and cutting wires out of a TV with built up charge. That was the first electronic device I broke into without any electrical specs or any knowledge on the amperage of the TV. The CRT TV's are so hard to get ahold of nowadays because a lot of times people scrap the TVs and people have stopped donating them to the thrift shops. Technology is changing and times are getting different. I didn't know what kind of TV would work so any CRT TV I seen I bought. I picked up two small TVs from the thrift shop after visiting 5 stores. I also seen a 22-inch CRT TV this guy on my street was throwing out on a very snowy day. I was so determined to get it home that I must have looked ridiculous trying to carry it. Some would call that determination. I needed a backup TV so that if I burnt or blew one up, which was expected knowing myself, I would be prepared for Murphy's Law to take action. Luckily, nothing blew up. Prayers work significantly and kept me safe. I had no clue how dangerous this little TV was. It did not include a spec with information pertaining to amperage and voltage. This was due to the Salvation Army’s “as is” purchase condition. The TV also had to be used with my variable power supply that my friend gave me. It did the job, but the potentiometer on it was giving misleading power signals and wasn't consistent with the TV’s natural settings. There was no way of measuring the output voltage on the 12 volt low amperage power supply. Ultimately, it can be hard to get the right settings to remotely turn on the TV. I later converted it with a 12 volt, 2 amp power supply, and a non-variable power supply I got at Microcenter. Basically, Microcenter was my second home in the tail end of my senior year. Also, knowing recently that the TV worked off of 2 amps, and that my hands were involved with working inside of the tv, terrifies me because two amps could kill a person. Looking back, I could have tried to look for the TV's electrical specs online or search for the model numbers. Part of the TV stickers were also in Spanish, which I assumed meant caution or danger. I have to get used to electricity being dangerous when I go into the field of engineering. This project was good practice. Over my years at CSI, and dealing with engineering projects, I quickly learned that engineering consisted of doing everything without knowing how to do it, yet being expected to know how to solve it. Nothing wrong with that method of teaching, as it helped strengthen my logical and problem-solving skills. Failure comes with testing, but without failure, it would simply mean your dreams aren't big enough. So, I carried on with it.

Failures. Oscillators were the other main component I struggled with. The concepts of trying to hook up the oscillators to the other factors was the hardest part. Right off the bat my oscillator didn't work then I hooked it up to the TV. It didn’t move the single stable dot beam displayed on the screen which made me disappointed, but not perturbed. This result didn’t prevent me from stopping, so I proceeded to reconstruct it many times after that. Still, no success. Later I found out that you need an amplifier to get the signal to even show. Soon after a second hall to the library to get my second compilation of electronic books, it all came into play and the research process began again. Let's get ready to rumble…I now wrestled with my brain trying to figure out how to get the amplifier to work. I bought some operational amplifiers at Microcenter, but they didn’t work even with the additional research on the concept of how to use the pins of the operational amplifiers. To sum it up, I was still confused. I built it on a breadboard about 10 plus times before I figured out how to wire it up to the oscillator. With each time, I hooked it up to the oscillator I still heard no intense high-frequency noise besides the non-negotiable hum of the annoying TV. No luck with the change in the single dot display on the luminescent screen. I started to speculate that my operational amplifier did not even work in the first place, maybe it was faulty. Later that evening I asked my dad if he had any old DJ equipment I could borrow to get this to work. He luckily had an old amplifier I could tinker with. I played with the amplifier for two days until my dad said the amplifier needed an audio Av cable. Before he said that to me, I was just shoving aux cords in the amplifier. Not only am I learning about older technology, I learned that older TVs had certain chords for them in comparison of today's TVs. I'm catching up on history from the past, which is educational. Before I figured this knowledge out and went to Microcenter again for the right cord for the TV to do the job, I was curious to know if my oscilloscope would even work. So, I hooked it up to my tablet and played YouTube videos. YouTube videos were played at full volume and I was starting to see results! It was reassuring to see some of my favorite songs being played while it was manipulating the TV waves that were being displayed on my homemade oscilloscope. I was so excited I yelled for my parents to see it. Though at the time I showed them the progress, it only showed the X-axis change in the display. The X-axis wasn't hooked up to the Y –axis, so it wasn't making cool shapes. The X-axis was only a thin line that was getting smaller and larger to the song beats and frequencies. It was still motivational to see it slightly work, but I wasn't satisfied with the results. Within two days, I figured out how to hook up the X & Y axis to the Tesla coils or deflection coils to get my desired effect and it worked really well! My behavior was mimicking a happy dog to see its owner at this point.

Success. My hard work produced progress, yet the extensive research within the three months still wasn’t over with. I’m still managing to get the oscillator to actually work at this point. I did find a working frequency sound generator app on the play store on my tablet. I figured if we had a full year to construct this capstone I would have no excuse not to get my homemade oscillator built. However, considering we got this Capstone Project with nearly three months to work on it, I am highly debating going with the sound frequency generator app. It effectively does the same thing as I'm trying to make by hand. During this process, I learned more than I could ever imagine pertaining to sound, visual, and electrical topics. It's been a very interesting project and I'm proud to push myself to accomplish what some thought I couldn't do. On top of the projects due dates and deadlines, I also participated in SkillsUSA, juggled working on other projects at the same time, traveled out of state on multiple occasions and worked on college requirement deadlines. These past few months have been very busy, due to graduation and other things out of my control. However, I'm very happy at managing to make my original proposal idea work out, even if it means using an app to generate different variable waves. I learned a great deal while doing this project even through all of the struggles, which seemed like endless trial and error. In in the end though, the pain was worth it because I learned an abundance of information which expanded my mind to the vast knowledge of electronics, which will continue to grow.

In conclusion, nothing will be fulfilling without a satisfying ending to my senior year here. This will be my last major project at CSI. I'm super thrilled because I chose a topic that involved many different aspects of the engineering field.

Ultimately, I was able to trigger more of my curiosity driven research and incorporate it into my oscilloscope to then infiltrate my findings in this composition. New ideas and concepts were learned throughout this process and was a significant success to gaining more exposure into the field of electrical engineering. By the end of this project I will have “figured it out”. As I reminisce on past projects and times at CSI, I think of how grateful I am for having had the opportunity to be one of the students here. CSI has given me hope and has changed me like variable metamorphosis potentiometers, so that I can shine bright with noticeable waves of awesomeness being displayed to the malleable future!

Works Cited

1. Battle, Sam. “STUFF.” LOOK MUM NO COMPUTER, www.lookmumnocomputer.com/projects/#/simplest-oscillator.
2. Britannica, The Editors of Encyclopaedia. “Oscillator.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 8 Feb. 2008, www.britannica.com/technology/oscillator-electronics.
3. Gerrish, Howard H., et al. Electricity and Electronics. Goodheart-Wilcox, 1999.
4. How to Wire an Inverting Amplifier Circuit. sites.psu.edu/jcz5041/files/2013/06/instructionsetfinal.pdf.
5. Maietta, Andrea, and Paolo Aliverti. The Maker's Manual: Maker Media, 2015.
6. McComb, Gordon. Gordon McComb's Gadgeteer's Goldmine!: 55 Space-Age Projects. Tab Books, 1990.
7. Slone, G. Randy. TAB Electronics Guide to Understanding Electricity and Electronics. McGraw-Hill, 2000.
8. Walsh, Ronald A. Electromechanical Design Handbook. McGraw-Hill,.
9. Wong, Kerry D. “Kerry D. Wong.” Kerry D. Wong: www.kerrywong.com/2014/03/19/bjt-in- reverse-avalanche-mode/.