Assignment 2 - Building a speaker
Designing and building a voice coil for a speaker
Soldering
Unfortunately I have no pictures of the soldering process. As I'm a bit new to documenting my process I forgot to take pictures while soldering the parts.
Voice coil
I was interested to see if the sound would be effected by the design if the coil is thicker on the outside than the inner part, and the other way around. To test this I made two spirals, that's because the it has to have two ends. To connect the + and -, so the electricity can get from one end to the other.
Designing
Building the first voice coil
Choosing material
Now I got to the point where I had to choose with what material I could build my design. Because my two spirals both have parts that are very thin my choice of material was influenced by what types of tools I could make such thin lines with. I chose to cut my design out of a sticker sheet with a vinylcutter. If I had done this with a lasercutter some of the thinner parts would have probably been messed up because of the heat that a lasercutter produces to cut through material. A vinylcutter uses a thin knife to cut in the material and adjust the speed and force.
I chose to cut the design out of a sticker sheet. To then remove the spiral from the sticker sheet and use the rest of the sticker sheet to stick on something so I could paint with a wire glue to make the spiral. Then remove the sticker sheet. So beforehand I chose a material that I thought the wire glue would stick onto and the sticker sheet could easily be removed from.
Placing coil on material
Step 1: Removing spiral from sticker sheet
Removing spiral from sticker sheet
Making wire glue spiral
As you can see the material started to wrinkle because of the wire glue. Unfortunately that also caused to glue to work its way under the sticker. So some of the lines were now glued together. Electricity takes the shortest route. Because of that it wouldn't follow the spiral, but instead will use the shortest route via the unintended spilled glue.
Result
Conclusion
Wire glue gives too much resistance and therefore it isn't a great material for a coil in a speaker. I should've first painted a bit a wire glue on a piece of paper to test how much resistance it creates. If I had done that before putting a few hours building this voice coil I could have spend more hours building a voice coil that would be able to work in the first place.
Building the second voice coil
For the second coil I used the vinyl cutter to cut out the spiral from a copper foil tape that is sticky from the back, just like a sticker with copper on the top so its able to lead electricity. I adjusted the force to 80g and speed to 2 cm/s, because copper foil tape needs a different force and speed to cut through than a sticker sheet.
Step 1
First I had to remove the spiral from the copper foil. This time I needed the spiral and not the material around it.
Step 2
Then place the spiral on some material. In this case I just chose to place it on some piece of paper.
Step 3
And remove the paper with soft glue, that I used to nicely remove the spiral from the copper foil, from the non-sticky side of the spiral.
Step 4
I measured a resistance of 0,5 - 0,6 ohm. The goal was to have a resistance about 4 - 8 ohm, so I needed add at least another 3,4 ohm.
Sources
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