@@ -40,17 +40,65 @@ I cut the same spiral shape but without the offset. Instead I just cut the line
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.
**Troubleshooting the coil**
The speaker made a very low sound, which is to be expected, since it has only 7 windings on the coil and I could only make them so tight. Making the coil trace thinner of leaving less offset would have made it impossible to transfer onto textile without shorting the traces somewhere.
What I did do was turn the volume on the mono amp all the way up. Added a few more magnets that I put *below* the coil instead of on top, giving the membrane (textile) a little more space to vibrate). I also used the multimeter to check the resistance in the coil. I couldn't get a stable reading easily so checked the two connections in my coil: one in the center where i connect a desoldering braid via the back, and one at the edge of the coil on the outside to make the other connection with a crocodile clip. I forgot to design it like that so just ironed on an extra piece, but the connection was less strong.
I soldered these connections to ensure a good flow of the current. Below a video of the technique. I heat the lycra a little by holding the iron *just above* the fabric, and then for a split second I touch the solder and conductive fabric, enough to flow. Super quick though or the lycra burns.
##SOLDERING VIDEO
I checked again with the multimeter, now I could get a stable reading of 17.7 ohm across. Which I will use for the Thermochromic circuit in which this coil will feature as a heating pad. I embroidered the number on for reference.
**Controlling a soft speaker with a DFPlayer Mini**
This board with a mini SD card holder that can work standalone or with an Arduino (not with the ATtiny though). You could make a full soft MP3 player with this chip! This is the [DFplayer Wiki](https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299) and here's [Liza's code](https://github.com/lizastark/Projects/tree/master/Sonic_Quilt/dfMini_tutorial) to start with.
## Thermochromic inks
## Thermochromic pigment + heating pad
**Making a transistor circuit**
We have a box of transistors here but I found out it's a mix of Voltage Regulators and Mosfets, they don't exactly do the same thing so I had to look at a lot of tiny numbers to find an N-channel MOSFET. I have a IRF530 here, that can control 100V-14A and the pinouts are the same as the example. Gate, Drain, Source from left to right when viewing it from the top.
I added a 1N4007 diode (1000V-1A) for safety in case I want to use it with motors etc at a later stage. Never hurts to protect a circuit. I used this one because it's what I had in my box of stuff, but didn't have the 1N4001 (50V - 1A) Liza suggested.
I added a 1N4007 diode (1000V-1A) for safety in case I want to use it with motors etc at a later stage. Never hurts to protect a circuit. I used this one because it's what I had in my box of stuff, but didn't have the 1N4001 (50V - 1A) Liza suggested. Emma wasn't sure why Liza would put a diode in series to one of the leads, instead of in parallel across the leads. We asked Liza and she said [...]
**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.
My 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. I opted for the lower end of the range and aimed at 500mA. Ohm's law tells me:
* I = 0.5
* R = 17.7
* and V = I*R = 0.5\*17.7 = 8.85V
So the Voltage should be 8.85V. I could power this circuit with a 9V battery as well, since I'm at the lower end of the range. For a smaller battery, I'd need to design a less resistive coil. To use a 5V battery for example, I'd need to reduce the resistance to 10Ohm by making the coil shorter or remaking it with a more conductive material.
I tested it with the Lab Power Supply and YES! The pad was getting nice and warm but not hot. Lovely.
**Experimenting with thermochromic pigment**
We managed to get our hands on two kinds of thermochromic pigment: black that turns grayish/white and green that turns white. I looked up [Kobakant's suggestions for thermochromic ink](https://www.kobakant.at/DIY/?p=3183) and understood that any dye/pigment/ink you might use for textile, you can use as a binder by just mixing in the pigment.
The only thing to think about is that a pigmented binder might outshine the thermochromic pigment. Using the pale army green with a bright turquoise will just annihilate the effect. If it creates a third color when you mix them, it will probably work. E.g.
The black pigment was very dried out, but I could easily dissolve it in a little bit of hot water, and crushing it gently until pasty and then dilute some more
* green pigment + yellow acrylic paint = light green > yellow
* black pigment + clear binder, like water = black > clear
* black pigment + pearl cream color = grayish pearl > cream pearl
* black pigment + well almost anything lighter than black works really nicely actually! Have a look at Bea's swatches, gorgeous.
###VIDEO HERE
I also experimented a bit with stenciling and stamping patterns onto the textile. The acrylic is a bit thick so allows for this quite well on a tightly woven fabric. When just using water, or using acrylic paint that is diluted a little bit more, its nice to paint by making paint strokes with a brush. The creases of the cling film also left interesting marks on the swatch I painted with heavily diluted yellow acrylic paint.
It could be nice to do these measurements a bit more precisely, but for now this will have to do....Still have many circuits to make this week.
####PICS HERE
##Emma's tutorial on motion & sound actuators
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@@ -281,7 +329,6 @@ Plays audio files from an SD card. OMG YES!
