Week 2 was the first official week of the minor, after the kick-off week. This week was all about the basics of electronics.
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Week 2 was the first official week of the minor, after the kick-off week. This week was all about the basics of electronics.
We started this week with a tutorial on connecting and debugging circuits. We learned about basic electronic circuits, and the laws that exist within those circuits. Those laws are:
Kirchhoff's first law: at any given junction within an electric circuit, the sum of the energy coming into that junction is equal to the sum of the energy leaving that junction. Within a junction, no energy can be stored or given away.
Kirchhoff's current law: the current within an electric circuit is the same at any given point.
Kirchhoff's voltage law: all of the voltage that is generated must be used up by components within the circuit.
Ohm's law: Ohm's law can be explained using a simple formula: V = I * R, where V is the voltage in volts, I is the current in ampere and R is the resistance in ohm. Knowing that the current is always the same within a circuit, the voltage and resistance have to be connected in some way. The higher the resistance at a certain point in the circuit, the higher the voltage will be. It's the same the other way around: the higher the voltage is, the higher the resistance will be. If you use the formula to calculate the current (I = V / R), you will only have to do this one time, since the current will be the same at any point in the circuit.
Using these laws, we were given the task to recreate three relatively simple circuits: an LED, an LED with a dimmer and parallel LEDs. First we will discuss the LED.
The image above shows the LED circuit. To make this circuit, I used copper tape (copper is a conductive metal, so energy can flow through it), a 3V battery, a resistor and a LED light. The circuit is completed by folding the folding line so, that both the anode (+) and cathode (-) are connected to the copper tape. You can connect the resistor any way you want using the copper tape, but the LED has a specific positive and negative wire. The positive wire is longer that the negative one, so it can be easily identified. Below shows different images of the LED working.
As shown in the picture above, the LED behaves differently, depending on the resistor that is connected. Ohm's law teaches us that, if the resistance is lower, the current will be higher. A higher current will result in a brighter light (I = V / R). Making this first circuit gave me no trouble. Now let's take a look at the second circuit: the LED dimmer, shown in the image below.
A lot of the circuit shown above works the same as the first circuit I made. A 3V battery, a resistor and a LED light are all connected in a circuit with copper tape. There is however a new component introduced here: a piece of velostat tape. Velostat has a unique property: its resistance changes depending on the amount of pressure that is applied. The more pressure, the lower the amount of resistance will be. The first circuit has taught us that a lower resistance will result in a brighter light, thus making a piece of velostat tape an ideal way to make a dimmer. When pressure is slowly applied to the tape, the light will slowly increase in intensity, as shown in the GIF below.
The last circuit I made is a circuit with parallel LEDs, shown in the image below.
For this circuit, no new components were introduced. The only thing that differs this circuit from the first one is the second LED that is connected parallel to the first one. The second LED however, is only connected at the positive leg.The first LED will light up normally if the battery is connected by both sides. If the negative leg is connected to the copper tape, the second LED should light up as well. However, mine didn't light up. Another law within circuits like these is that the electricity will always choose the route with the lowest resistance. Because I used LEDs with different resistances (a different color means a different resistance), and the green LED had a higher resistance than the yellow LED, the electricity will only flow through the yellow LED, causing the yellow LED to light up and the green to not light up. If I had used two of the same LEDs, it would have worked as desired.
To know beforehand if the coil would even work, you can measure the amount of resistance the coil has in ohms. The teachers put up a helpful chart that told the resistance of all kinds of material per winding. Our coil would have a resistance of around 3.6 ohms. The ideal resistance lays in between 4 and 8 ohms. That means we could expect our coil to work, but pretty quietly.
Finally, to test the coil, it needs to be connected to a phone, a battery and to the previously created amplifier. You can first connect the crocodile clips to both ends of the coil that you made. For the battery we use a voltage supply. Set the voltage to 5V and the current to 0,250 Ampere. Connect the black wire to the ground wire soldered to the motherboard. In our case this is the white wire. Connect the red wire of the voltage supply to the brown wire. Next, place the coil on top of a carton coffee cup. Let it rest so that the coil sits in the middle. Now connect the auxiliary cable to your phone and play music. Finally hover the magnets that were provided by the minor just above your coil. If you have done everything right, you should hear music.
To our surprise, we heard a very distorted sound. No music could really be identified from it. We tried to find out what happened, but couldn't wrap my head around it. Suddenly, Thijs made the remark that the sound was very bass heavy. I suddenly put two and two together: the music I had chosen was very bass heavy. The amplifier and/or the coil simply weren't powerful enough to translate that to good quality sound. I switched the music to Adele (because why not) and we could hear her beautiful voice quietly, but very clearly. So we knew we had a properly working coil.
A speaker like this could be sewn into a small night cap for small children. This could provide them with soft music to help them sleep at night. This could be beneficial for their own development and also beneficial for the parents, who don't need to wake up to help their children sleep..
After the circuits taught me the basics of electronics, I was given the task to make a simple speaker. For this assignment, I collaborated with Thijs Uffen.
Based on the circuits I made in part I, it was time for the week assignment: making a working speaker. This assignment was to be done in pairs. I paired up with Thijs Uffen for this assignment. The first step was to make an amplifier. Components for this were provided to us by the minor. These were: a circuit board, one crocodile clip, four wires with male and female sides, one (...), five wire connectors and an unconnected auxiliary jack. To assemble the amplifier, use the following steps:
Using the soldering iron, solder the (...) to the circuit board. Make sure it's soldered at the side with the positive and negative side on the circuit board.
Solder the 5 connecting points to the other side of the circuit board.
Use scissors to cut the crocodile clip in two and strip both cut sides of the wire so that the fibers are exposed.
Screw the fibers of the exposed wire into the (...) that is soldered to the circuit board.
Cut the male parts of the four wires and strip them the same as the crocodile clip.
Connect the female parts of two of these wires to the circuit board (audio in + and audio in -).
Solder the stripped male parts to the two poles of the auxiliary jack. The positive pole is the short one!
Connect the female parts of the other two wires to the circuit board as well (Ground and 2-5VDC). Ground is the positive one.
You know have a working amplifier! You can check with the Multimeter if everything is connected properly.
With the amplifier working as desired, it was time to design the coil. Thijs and I wanted to work with the vinyl cutter to make our coil. We had chosen to work with copper foil to make our coil, because we had worked with this material before during the making of the circuits in Part I. We already knew this material was conductive and thus could be used in the making of a coil. Thijs used his knowledge with Adobe Illustrator to design a coil with a relatively simple, yet appealing design:
This design could then be uploaded to the vinyl cutter that is located in the Maker's Lab. There are a couple of settings that need to be set correctly in order for the vinyl cutter to work properly:
You need to insert the green knife into the machine. This one is meant for copper paper. The white one is meant for normal paper.
The cutting speed needs to be set to 80 in/s.
The pressure of the knife needs to be set to (...)
You need to insert the material (the copper foil) so that both scanners of the vinyl cutter are covered. The vinyl cutter will then scan your material so it will know the boundaries of where it can cut. Once that is done, you can open CutStudio and import the Illustrator file. Then press the R button in the top right corner. Then you need to go to file -> cutting setup -> property -> get from machine, and press OK twice. The program now has the same settings you put in the vinyl cutter. Press Origin on the vinyl cutter so that the knife will move to its starting position. You can now press Cutting to start the cut.
Unfortunately our design was flawed. There was not enough space in between the different coil windings. This caused the knife to have to cut lines that are very close to each other, which in turn caused the copper foil to unstick from it's sticking layer, which ruined to coil, as seen below:
We tried to increase the space in between the windings, but it was still not enough to make the copper foil stick to the sticker layer. Because of time issues, we decided to abandon the vinyl cutter and think of another way to make a coil. During brainstorming, Loes came to us with a great idea for a coil. It consisted of a piece of denim that is nailed on a piece of wood (I used twelve nails. They are nailed in a circular pattern). You then use copper wire to wind around the nails in the pattern shown below:
Once you finished winding the coil, you sew the twelve nodes of the coil to the denim so you can remove the nails. It's quite a simple design but it looks really cool (and Loes promised extra credit if we used it :D). The two ends of the copper wire are meant to serve as the positive and negative connection (it doesn't matter which one is which).
