@@ -45,20 +45,52 @@ I think I might be able to make a better contribution there because I enjoy solv
###Understanding softpot basics
**Varying resistance across**
The basic idea of a (soft or hard) potentiometer is to align a very conductive material with one that has resistance, and designing a physical sliding connector that connects them across. The shape or design can be straight or round or even meandering as shown on this swatch from Kobakant:
![]()*Embroidered potentiometer, screenshot from [Kobakant](https://www.kobakant.at/DIY/?p=2331)*
The sliding connector can be any conductive object or material. The further away you put the sliding connector - or: *conductive pointer finger* from the source, the more resistance there will be. If you know the the minimum resistance value and the maximum value, you can even map out pretty precise in-between states (as long as your resistive material increases in a linear way, not all materials behave like that).I started out with some conductive and some resistive thread and tried sewing some lines on my sewing machine. It has a lot of patterns preprogrammed and some of them are pretty nice! So I tried a few of those.
Liza Stark's slides made things very simple.
![]()*Screenshots of Liza's slides for reference, 2019*
**Tension and test traces**
I wanted to sew some test traces with resistive and conductive thread so I could measure how the resistance changed across (and perhaps consider a voltage divider).
The resistive thread was ok to sew as long as I went very slowly (my machine has a limiter for this, called "langzaam naaien" that you can toggle on. Pretty nice. I also had to lower the tension a little. I learned that you can adjust the tension on top with the wheel on the left of my machine, and mine has a front loader spool on the bottom that has a little screw you can loosen or tighten to adjust the tension of the bottom thread.
It wasn't easy to sew in one continuous line without breaking the thread, but I managed at least one lines. Especially when doing patterns it's annoying when it breaks because you break the pattern and will not be able to continue in exactly the right place. Disrupting the continuity of the patter you're trying to make.
The tension between the threads should be equal so each thread keeps to its own side of the fabric :)
[INSERT VIDEO]
Sewing with the conductive thread was a lot harder to do! I didn't quite get the tension right but did sew a zig zag line which for testing purposes was enough. So I connected my multimeter, put it on the Ohm setting and put my Danish krone across to get some readings!
**Coated vs. uncoated conductive thread**
**Sewing machine dramarama**
I thought I was crazy and/or my multimeter was broken because the readings were super erratic. After taking some distance from it (of course this was late in the evening) I realised the conductive thread may have been coated. This means it's still conductive – on the inside - but it's hard to connect to that conductive inside because there's an insulation layer around it.
###Testing a bikini clip/switch
Cecilia and I tried to melt away a bit of coating from a piece of thread, using a lighter. After removing the coating on two sides I was able to get readings from a piece of thread. It's easy to break this thread while burning it though, it's so thin. I tried melting some off the stitch I'd already done, but this didn't really work. Also, I would need the stitch to be connecting to the slider all across (so I would need to undress the entire length). I drew the conclusion that uncoated conductive thread would probably be better for making this softpot.
**Sewing machine dramarama**
I found a new thread, barely got one stitch done....and then my machine broke. It has this thing with the pedal that it creates shorts sometimes, driving my machine cray cray. I will have to open it up and dust off the insides and check the connections or connect another pedal (I think I have one somewhere). Ok, well. I see how the basics will work. Moving on to designing the circuit for now.
###Testing a bikini clip/switch
I found this metal bikini clip that I cut off a bikini once. It's really nice! My multimeter says I can use it (beep beep). Great! Off I go to prototype the digital circuit. Emma Pareschi, our electronics miracle worker at the Amsterdam lab provided us with the basic schematics that helped me quickly put together a circuit with a the digital switch and an LED. I'm not sure why she's opted for a pullup resistor here, maybe because the Arduino has an internal pullup so it's easy to switch between. But I'd say it makes more sense to use a pulldown that keeps the buttonState LOW unless pressed. I know you can change it in the code too, so whatever. But basically it would mean putting the resistor on the other end of the button, the one that connects to GND. @Emma can you explain why you use a pullup and not a pulldown? Does it matter?
##Building the digital circuit
###Using Arduino Uno
Prototyping this with an Arduino was a breeze. I started with a Blink sketch, and then added the code from the Button example
**Tone() for my buzzer**
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@@ -87,8 +119,62 @@ This code is a bit lower level, programming the chip directly instead of using a
```
CODE CODE CODE
/*
Code from http://www.technoblogy.com/show?20MO
Playing Notes on the ATtiny85
31st January 2018
This article describes a simple function for playing notes on the ATtiny85.
I've called this function note, and it can be used to play notes on the ATtiny85 pins 1 or 4.
The note function uses Timer/Counter1 in the ATtiny85,
leaving Timer/Counter0 free for delay() and millis().
It doesn't use interrupts, so the sound output is unaffected by other interrupt-driven processes,
and it includes a lookup table for the well-tempered scale divisors, so you don't need to remember frequency values.
It's an improved version of my earlier article Simple Tones for ATtiny.
For a similar routine for the ATmega328 or ATmega32u4 see A Lightweight Alternative to tone.
The note function takes two parameters:
A note number, from 0 to 11, representing the note in the well-tempered scale,
where 0 represents C, 1 represents C#, and so on up to 11 for B.
The octave, which can be from 0 to 7 with a 1MHz clock,
@@ -110,30 +196,90 @@ command. If it wasn't the issue then it's at least good practice.
Faulty wiring. I am shorting my circuit everything I connect the switch ends together because the switch is directly between VCC and GND. The + wire should be connected to VCC not directly, but via the 10K pullup resistor. Errrp my bad. This solved the issues though and I have a working circuit using the components I'd intended. Wahoo! Ready to start crafting it into a textile swatch.
###Powering the circuit
Now, powering this stuff with a USB cable (5V) is usually fine, but will it blend with say, a 3V coin cell, is what I want to know. The Lilypad Buzzer datasheet says yes, as the operating voltage should be 2.5-4.5V. The ATtiny85 datasheet says 1.8-5.5V for the ATtiny85V and 2.7-5.5V for the ATtiny85. So let's take the latter to be on the safe side. ([ATtiny85 Datasheet](https://html.alldatasheet.com/html-pdf/175195/ATMEL/ATTINY85/151/1/ATTINY85.html), and the [datasheet of the buzzer used on the Lilypad Buzzer](http://cdn.sparkfun.com/datasheets/Components/General/CCV-084B16-CUI-datasheet-29139.pdf)). Ok now that I know this I will try power the buzzer and IC with a 3V coin cell. Went back to simple tone sketch I stole, and...Success!
```
CODE CODE CODE
```
/*
Code from http://www.technoblogy.com/show?20MO
###Powering the circuit
Playing Notes on the ATtiny85
31st January 2018
This article describes a simple function for playing notes on the ATtiny85.
I've called this function note, and it can be used to play notes on the ATtiny85 pins 1 or 4.
The note function uses Timer/Counter1 in the ATtiny85,
leaving Timer/Counter0 free for delay() and millis().
It doesn't use interrupts, so the sound output is unaffected by other interrupt-driven processes, and it includes a lookup table for the well-tempered scale divisors, so you don't need to remember frequency values.
**Power without a computer?**
It's an improved version of my earlier article Simple Tones for ATtiny.
For a similar routine for the ATmega328 or ATmega32u4 see A Lightweight Alternative to tone.
The note function takes two parameters:
A note number, from 0 to 11, representing the note in the well-tempered scale,
where 0 represents C, 1 represents C#, and so on up to 11 for B.
The octave, which can be from 0 to 7 with a 1MHz clock,
0 to 10 with an 8MHz clock,
and 0 to 11 with a 16MHz clock.
*/
const int ledPin = 0; // the number of the LED pin > has PWM
@@ -15,12 +15,15 @@ We prepared alginate plastic that we cured with calcium chloride, and lastly we
My favourites? The egg shell/gelatin potluck foam, my alginate earring and button (and piercing and hand stitchingalginate in general). And the *process*! What a sensual week this was. I did not know what I wanted from these unfamiliar goos and mushes so felt a little lost, but eventually embraced and appreciated the fact I did not need to control the output for this week, just play, explore, and document findings.
*Some later results, the sheets I made with Bela and Bea, wowwwww.... Top and left: agar/gelatine foil with (cooked) tapioca, blue foodcoloring and blauwhout. Bottom: Agar and gelatine biofoil with foodcoloring. Loes Bogers, 2019*
*Conclusions and more questions/urges*
* Making/growing materials is not like making instant soup. It takes a good amount of time and each period or gesture requires dedication, due consideration, and careful observation (I found out after the fact, unfortunately).
* Time is like a box of chocolates: you never know what you're going to get or: how my voluptuous, satisfying blobs turned into dry wrinkled raisins (with some exceptions!)
* Making materials is a very sensual and satisfying, yet stinky experience. And then everything starts to shrink.
* I am now known as the left-over queen (and couldn't cast a bioplastic sheet to save my life)
* I am now known as the left-over queen
* ~I couldn't cast a bioplastic sheet to save my life~. Nope not true! I *can* and did cast some beautiful sheets with Bela and Bea! <3
* Making a bioplastic bottle appear out of an erlenmeyer bottle is a pretty good party trick
* Further research urges: practice casting larger sheets so I can give myself surfaces and options to further craft with. Larger egg shell foams (formulate a non-potluck recipe). Making some of materials conductive, then insulating the conductive materials with alginate plastic.
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@@ -288,15 +291,10 @@ I forgot to do this when using the wheat flour and got huge lumps. I thought it
Thicker ones are still moist and cold, squishy/rubbery. The thinly casted foils with rice flour are rigid, and pretty brittle, whilst still a little flexible.
[](https://gifyu.com/image/kJYz)*Agar-based biofoils with raw stiffeners (left to right:) wheat flour dumped in without dissolving, rice flour and tapioca dissolved cold and mixed in, Loes Bogers, 2019*
**Attempt to cast a large sheet of foil**
The raw rice flour made the mixture thicker and easier to pour without making elaborate frames, but also shrank loads. This could be because of the rice flour, or because I poured it out onto a bigger surface, and a bit thinner, I'm not sure.
We also made a leftover pot with tapioca that we mixed into the recipe and then continued cooking a little longer so the tapioca was no longer raw. We added some natural inks that we didn't mix and Bela and I had a glorious pouring experience in purple. The next day it turned a light blue. It's now partially rock solid and partically sticky, so it's still curing...
*Bela and me trying to cast a large piece of foil with cooked tapioca as stiffener and natural ink. It turned light blue since and is still drying, Loes Bogers, 2019*
[](https://gifyu.com/image/kJYz)*Agar-based biofoils with raw stiffeners (left to right:) wheat flour dumped in without dissolving, rice flour and tapioca dissolved cold and mixed in, Loes Bogers, 2019*
###Agar/gelatin biofoil
...
...
@@ -324,6 +322,42 @@ Brittle and rigid, very little flexibility. The tapioca sample dried a lot slowe
[](https://gifyu.com/image/kJYH)*Gelatine/agar biofoil with food coloring and raw rice flour (left) and raw tapioca (right), Loes Bogers, 2019.*
**Leftover pot thickened with cooked tapioca**
We also made a leftover pot with tapioca that we mixed into the recipe and then continued cooking a little longer so the tapioca was no longer raw. We added some natural inks that we didn't mix and Bela and I had a glorious experience pouring it onto a sheet of acrylic. The next day it turned a light blue. It's now partially rock solid and partically sticky, so it's still curing...
* 300 ml water
* 14 gr tapioca (dissolved in a little liquid before adding to the pot, then cooking it until thick)
* 100 ml agar/gelatine foil mix
* blue foodcoloring & blauwhout in ethanol ink (not mixed together, mixed slightly during slow pouring.
*Bela and me trying to cast a large piece of foil with cooked tapioca as stiffener and natural ink. It turned light blue since during the drying process, Loes Bogers, 2019*
*The blue result, video of releasing process, Loes Bogers, 2019*
**A fresh batch to make some sheets**
Bea and I cooked another batch of gelatine/agar foil to make some thin sheets we could play with and try different fabrication techniques on. Like making interlocking modules with the laser cutter. We cooked a batch that we dyed with food coloring. The stove didn't quite reach 80 degrees like it should so it took quite long to thicken. You can turn up the cooker slightly higher just making sure it's not bubbling and boiling (then I turn it down again, and go up and down like that).
We cast one sheet while the mix was still very liquid, which turned into a beautiful lightweight foil with a very shiny back. (Video's below shot by Bea, while Cecilia is releasing the foil.
The other sheet was poured when the mixture was properly thickened and became a beautiful strong and shiny sheet. WHOA! They even sound nice. Satisfaction all around.
Using a thinner sheet allows you to bend the acrylic in different directions (slightly), which creates a surface tension that helps the foil release, as shown by Cecilia in the video below. Once a little edge is off the rest is easier. For example the blue tapioca foil was really brittle, so the edges (that are thinner) cracked easily. A stanley knife helped me creep below the thinner edges and allowed me to salvage the foil quite well (see video above).
Alginate plastic is bioplastic that is heat resistant up to 150 degrees celcius. It can be made using the technique of *spherification* – where you drop liquid that contains sodium alginate into a calcium chloride bath, resulting in perfect balls if that's what you're after. Or through *reverse spherification* – where a high acid/alcohol/calcium mixture such as lactate is dripped into a sodium alginate bath, typically resulting in blobs. But this all depends on your recipe I guess. Related techniques, using the same two components:
