LED Flasher as a Mini System

Leader: Ore AfolayanCertifier: Kelvin Darden

AbstractThis project will show display the use of a 555 IC and other components such as resistors and capacitors in a mini system.

IntroductionWe built an electronic system using an Input-Processing-Output configuration. We utilized the 555 integrated circuit. The first creation was that of a visual output in the form of a flashing LED. The second was an audible representation, a speaker. This report will display how to build the system, how the different components interact with each other to form the system, and the different problems that can occur.

Learning StylesAs we prepared to construct the system, we viewed the diagram in the RadioShack manual. From this, we determined that we learn the best visually. In developing the project, we took a more active approach rather than reflective. Our hands-on work with the system allowed us to better familiarize ourselves with it and increased our learning and understanding. As our building continued, we learned from our errors and successes and figured out how the system works as well as the roles the different parts play. In addition to these learning styles, we opened ourselves up the Benjamin Bloom’s three domains. In regard to the cognitive application, we learned about the LED flasher system, and by studying it, we increased our understanding of it and were able to replicate it and turn it into a speaker as well. For the affective application, when the system finally worked, it made us happy. However, we came across problems along the way, which frustrated and angered us. That anger and frustration was used to further motivated us to diagnose the problems and fix them. The psychomotor application came into play as we got hands on work with the system, which gave use an idea of how future systems might operate and thus increased our knowledge and experience.

Team BuildingThroughout working on the assignment, we learned that in order to complete a team project, it is important that that team recognizes each other’s strengths and weaknesses and splits up work to help eliminate stress and pressure. Putting each other’s brains together is also very crucial because, for example, if one person isn’t able to think of a solution to a problem, another team member can compensate for it and help out.

Basics

Figure 1. Components of the system

Figure 2. Circuit Diagram

Figure 1 displays the different items that were needed from the kit in order to construct the IPO system. It requires a 555 IC, 3 resistors, a capacitor, and the LED. Figure 2 shows the different roles the components play. The input of the IPO system was the 6-volt source that powered the circuit. A series of resistors process this input and limit the amount of current going through the system so nothing is overloaded. The current is then sent to the capacitor. The capacitor will store the charge and then discharge when full. The charge then discharges into the 555, and finally the circuit directs the current to the LED output.

AnalysisThe circuit uses and input-processing-output system. The input is the 6-volt power source, the resistors, capacitor, and 555 IC then processes that input and then sends the charge to the LED output.

The two resistors on the left side as well as the capacitor determine the frequency of the flashes.

Figure 3. Frequency equation

This constitutes what is called an RC time constant. The current going into the LED is determined by the source as well as R3. Therefore, increasing the amount of voltage going into the LED and/or decreasing R3 would cause the LED to flash brighter.

TestingWe gathered all of the components needed for the system (LED, resistors, capacitor, 555) and put them in their proper places on the breadboard. If the LED didn’t flash, we checked to see if everything was secured in place and/or if anything was misplaced. One of our initial errors that cause the LED not to flash was the fact that the system was not grounded.

Figure 4. MultiSim computer simulation

After we constructed the physical electronic system on the RadioShack breadboard, we utilized the computer program MultiSim and created a computer simulation of the system. The simulation uses all of the same components as the real system. We put everything together in the simulator and tested it to make sure everything worked as it was supposed to. We even connected an oscilloscope to measure and observe what kind of signal was going into the LED. Another day, all of the parts in the physical system came apart so we had to reconstruct it. Upon turning it on to see if it functioned properly, we noticed that the LED was flashing but it was very dim and hard to see. We then started troubleshooting some of the possible issues. First, we changed the batteries of the breadboard just in case they were faulty. After changing them, the LED was still flashing dimly. Then, we used a multimeter to measure the strength of the current. Everything seemed fine, so we turned on the system again and still no change was made. We proceeded to ensure that the right resistors were in the right places and that we had the right capacitor. Next, we thought the 555 IC might be at fault so we carefully removed it and replaced it with a different one. After doing so, still nothing changed. Finally, we thought to change the LED and then it flashed normally. However, when we changed the output from the LED to the speaker, the sound was very faint. We went through the troubleshooting process and unfortunately, we were unable to determine the cause of the faint speaker.

Other Applications

Figure 5. Speaker

After working with the LED long enough, we decided to change it up a little bit. We replaced the LED with a speaker, as shown in figure 5. Everything else works pretty much the same, except now instead of a blinking light, the speaker plays a beeping noise.

Figure 6. Sim with a second LED

Additionally, we did more work with MultiSim and attached a fourth resistor as well as a second LED. Now, when turning on the system, the two LEDs alternate.

ConclusionThrough working on this project, we found out that we learn better visually rather than verbally, as we were able to construct the circuit by looking at the diagram in the RadioShack workbook. We were able to see how Bloom’s Taxonomy applied to us in a project environment. Using MultiSim, we were able to reconstruct the system with a computer program. Finally, we were able to experience how to create two different IPO, one with an LED and one with a speaker, as well as an electronic simulation of alternating LEDs.

References[1] Mims III, F. M., “Electronic Sensorlab Workbook,” RadioShack, Fort Worth, TX.[2] Mims III, F. M., “Basic Electronics Workbook I,” RadioShack, Fort Worth, TX.