finished week 10

docs/assignments/week10.md

 # 10. E-Textiles and Wearables II
 
+![](../images/wk10_blackdiamondswatch1.jpg)*A capacative sensing swatch with a black conductive alum crystal I grew in week 9, Loes Bogers, 2019*
+
 ![](../images/wk10_heatpad1.jpg)*Lookit! My heating pad powered with a 9V battery, transistor controlled by an ATtiny (details below), Loes Bogers, 2019*
 
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@@ -17,9 +19,21 @@
 
 *A choker with an alarm that sounds when you take it off (see week 5 for process), Loes Bogers, 2019*
 
+For the week I decided to make a number of coils that I could use both as a speaker and as a heating pad. Even the code turned out to be exactly the same which was really interesting to realise :) Simple principles with 1001 applications, that's beauty right there. I loved going into the bare bones of the physics of electronics this week, I think this is how electronics should be taught to anyone, so we can understand how material properties and laws of physics interact and how you can bend them a little to achieve interesting results and expressions.
+
 ##Soft Speakers
 
-**Variables**
+**Making a jack connector and soldering the amp board**
+
+I started of by making a jack connector connected to a mono amp board following the tutorial Liza mentioned. I added some shrink tube to insulate the wires inside the metal cylinder. I soldered the amp board together and turned the volume knob on the board up to max with a tiny screwdriver. The board used is an Adafruit Mono 2.5W Class D audio amplifier and Liza describes how to make this jack connector [here](http://thesoftcircuiteer.net/custom-mono-amp-for-textile-speakers/).
+
+![](../images/wk10_jackattack.jpg)*Jack plug soldered to a Mono Amp, Loes Bogers, 2019*
+
+**Designing & Fabricating coils**
+
+What makes for a good coil? I guess I will be able to answer this question at the end of the week haha. But we received the parameters to play with. I spent most of the week figuring out and puzzling what makes for a good membrane. It seems to be something light that doesn't let air through. So cellophane or cling film was mentioned by Anastasia, but I also got really good results from a fake leather swatch interestingly enough, not so light but pretty airtight.
+
+*Variables*
 
 * **Coil tightness:**
 The tighter the coil, the louder. (It will be since it will have a stronger magnetic field.)
@@ -29,21 +43,16 @@ The larger the magnet, the louder the volume. You can combine many small magnets
 * **Magnet placement**
 The volume will be louder the closer the magnet is to the center of the coil.
 
-**Making a jack connector and soldering the amp board**
-
-See tutorial Liza mentioned. Added some shrink tube. I soldered the amp board together and turned the volume knob on the board up to max with a tiny screwdriver. The board used is an Adafruit Mono 2.5W Class D audio amplifier and Liza describes how to make this jack connector [here](http://thesoftcircuiteer.net/custom-mono-amp-for-textile-speakers/).
-
-![](../images/wk10_jackattack.jpg)*Jack plug soldered to a Mono Amp, Loes Bogers, 2019*
-
-**Designing & Fabricating coils**
 
-*Needlepointing (Liza's instructions)*
+**Liza's instructions to design a coil for needlepointing**
 
 Draw a coil on your fabric or paper. It can be any shape you like. Thread your needle with one strand of conductive thread. You can run wax over the end to get it through the hole. Tie a knot 5-6 inches from the end. Come up through the center of the piece of fabric. Stitch around the coil, making sure the conductive thread lines do not touch each other. Make sure the extra 5-6 inches of thread does not get sewn into the coil! We need to keep them separate.
 
 
 **Lasercutting and heat'n bond**
 
+I decided to also try lasercutting a coil from conductive fabric that I could attach with heat 'n bond, since I hadn't tried that yet. So I designed a simple spiral in rhino that I tweaked a little in illustrator. I forgot to design the leads to the edge of the swatch though, so I had to add pieces at the end and solder them together to ensure a good connection. 
+
 * Rhino: Spiral
 * Illustrator: offset, add extra lines. 
 
@@ -51,11 +60,11 @@ I designed lines of the spiral to be 3mm thick so I could still handle them. Too
 
 ![](../images/wk10_heatnbond.jpg)*Preparing the conductive textile by ironing on heat 'n bond, Loes Bogers, 2019*
 
-Iron heat 'n bond to the conductive fabric before laser cutting (I put a little piece of cotton canvas over it to prevent the plastic melting to the iron. I kept the backing paper during the lasercutting. Cut with laser cutter at Speed 100/Power 20. I had to tape it down a few times to keep it from burning. Carefully ironed the coil to the textile, added a soldering braid from the back by making a little cut in the center so I could connect to both sides. 
+I ironed the heat 'n bond to the conductive fabric before laser cutting (I put a little piece of cotton canvas over it to prevent the plastic melting to the iron. I kept the backing paper during the lasercutting and cut with laser cutter at Speed 100/Power 20. I had to tape it down a few times to keep it from burning. I then carefully ironed the coil to the textile. And finally I added a soldering braid from the back by making a little cut in the center so I could connect to both sides of the coil. A stuck a bit of tape on the back to prevent shorts.
 
 ![](../images/wk10_cutting.jpg)*Trying to prevent the coil from going everywhere, Loes Bogers, 2019*
 
-Cut off a few windings because I couldn't get them on neatly. So it's a relatively small and weak coil. But it works! You have to get close but you can clearly hear the music with a stack of 5-10 magnets.
+I had to cut off a few windings because I couldn't get them on neatly. So it's a relatively small and weak coil. But it works! You have to get close but you can clearly hear the music with a stack of 5-10 magnets.
 
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@@ -152,6 +161,12 @@ Important note for audio files. Careful read notes below will save you a lot of
 
 Source: https://www.dfrobot.com/blog-277.html 
 
+## Intermezzo: the state of the lab
+
+We tidied up the entire lab last week, it was so bright and shiny and calm when we started the week! A few days in: BOOM! Exploded again hahahha. Working with electronics is such a hot mess!
+
+![](../images/wk10_labspace.jpg)*Our gorgeous mess, Loes Bogers, 2019*
+
 
 ## Thermochromic pigment + heating pad
 
@@ -193,7 +208,7 @@ I added a 1N4007 diode (1000V-1A) for safety in case I want to use it with motor
 
 **Calculations to use the coil as heating pad**
 
-Since I had a coil that I could use as a heating pad as well, I decided to use it for this experiment as well, at least until I have another coil swatch which I'm working on. 
+Since I had a coil that I could use as a heating pad too, I decided to use it for this experiment as well, at least until I have another coil swatch which I'm working on. 
 
 My lasercut coil from lead to lead measures 17.7 Ohm, and I want to run 500mA-1A across the coil so it dissipates a little heat. If I'd aim for 0.5A, Ohm's law will tell me: 
 
@@ -441,24 +456,30 @@ void loop() {
 
 **Preparing an integrated swatch**
 
-Made schematic
+I had to change the schematic and code a little bit when I added the LED to the circuit, because I had no PWM pins left to put it on so had to move stuff around. I moved the TX pin from pin 0 to pin 2 so I could free up pin 0 for the LED to fade. Pin 3 and 4 stay there because I need ADC for analogReads of the capacitive sensor.
+
+To be clear, the schematic above was changed a little. With the code above (that has the LED in it as well), THIS is the circuit for it: 
+
+![..](../images/wk10_schematic_swatch.jpg)*The updated schematic that works with the code posted above (RX pin moved from pin 0 to pin 2, LED pin on pin 0), Loes Bogers, 2019*
+
+**Hard-soft connections for IC and power pads**
 
-did some soldering tests
+Then I went on to prepare the hard-soft connections a little bit. I had issues with the power supply and IC before, they seem to be the hardest to get right. I wanted to add bigger connector pads for my alligator clips to power the swatch and hand cut them from some conductive textile with heat 'n bond, there were plenty of leftovers to do this with. 
 
-![](../images/wk10_swatchmaking.jpg)*, Loes Bogers, 2019*
+![](../images/wk10_solderingleads.jpg)*Preparing the power connectors by adding a bit of solder to the textile and thread first, Loes Bogers, 2019*
 
-Drew a simple design
+For the IC, I thought I could maybe work with the crimp beads I found. They're basically small metal cylinders that you can squeeze shut with plyers. I prepared the IC socket by pusing it through the neoprene and putting some solder on the legs, then I put some solder on the crimp beads, and finally I soldered the crimp beads to the legs. What a figdety job, but it worked. The beads are a bit wider than the distance between the legs but since the Attiny85 has only 8 legs, you can bend the legs outward to make sure they don't touch. 
 
-Freehanded the rest
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-Awful wire > don't use! Better stainless steel
 
+*Designing the swatch*
 
-![](../images/wk10_swatchmaking.jpg)*preparing the components to make a swatch, Loes Bogers, 2019*
+I drew a basic layout of the design, of where the components would be, and how the traces might run, but basically freehanded the rest. I used a beautiful black and gold conductive wire. It's gorgeous, but also breaks easily. The metal strands snap easily when you pull at it. So this only really works nicely with the right size needle and a fabric that is a bit more loosely woven of perforated, it's just too easy to snap the conductive strands of the wire leaving your traces broken. Gorgeous though. I did switch o stainless steel for the black diamond part of the circuit, partially because I was fed up and partially because I wanted to know if it was easier to connect to the IC/crimpbead-connectors. Definitely easier. 
 
-Checking connections, all good
+![](../images/wk10_swatchcollage.jpg)*From schematic to swatch, Loes Bogers, 2019*
 
-Slightly different behavior when powered but everything seemed right, might need to recalibrate to optimize but it works!
+Then I thoroughly checked all connections, which seemed in order. In the video below you will see slightly different behavior compared to the test with the breadboard. That's because originally the diamond was two rocks attached to each other but one broke off in the process of stitching the swatch. That 50% of the surface gone, so the circuit is a little less sensitive and needs to be recalibrated to be optimized again. But everything seems right and it works!
 
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