Familiar Materials for Unusual Circuits

Over the past couple weeks, it has been great to check out the rebelmouse page for inspirations and innovations from participants in our coursera course as they build scribbling machines, sewn circuits and other electricity-minded projects.

I was intrigued by Marlene's coin cell battery holder using a key cover and a metal brad. It's super simple and and looks like it works great. I especially like how these materials are much cheaper than the sew on battery packs and show evience of tinkering in the design.

It reminded me of another novel approach to attaching motors and batteries for a electric vehicle activity from the Ecsite conference earlier this summer. Xander from the TrashLab used pushpins and paperclips soldered to the components to make homemade switches.

These connections could easily be adjusted and reconfigured to turn the propeller on and off. I like how both of these examples use extremely common materials to create electrical connections. These types of solutions can inform what kind of materials to use with different activities and can really make circuits more approachable.



rain-sensing umbrella

We are always looking for new ways to experiement with circuits in the Tinkering Studio, and when you're looking for inspiration, it's hard to beat Forrest M. Mims III's books. He uses simple, familiar materials to build sensors and circuits, with really clear illustrations and explanations to boot. I love his hand-drawn illustrations, too. They are inviting and accessible, which is not something I usually think when I see circuit diagrams. 

I was particularly inspired by this rain-sensor, and I had to try it out.

rain sensor

I started by building a simple version of the sensor with copper tape and LEDs. It's tricky prototyping in the rain, so I tested the circuit out in our workshop first, where I used a pipette to simulate the raindrops.

When the drops bridged the gaps between the strips of copper tape, they completed the circuit and the LEDs lit up. I was really surprised how responsive the LEDs were. The amount of water bridging the gaps between the strips of copper tape really affected the brightness of the LEDS. The more water was on the sensor, the more electricity flowed through the LEDs, and the brighter they glowed. As the water evaporated, the LEDs slowly faded. The result was really lovely.

The next step was putting the sensor to some practical use, and trying it out in the real world. I thought it would be neat to have a rain-activated umbrella that would light up when it rained. The greyer and gloomier the day, the brighter the umbrella would glow. 

Luckily, the copper tape has a sticky side, so it was easy to attach the circuit to an umbrella. I made the sensor larger on the umbrella, to increase the chances of detecting raindrops. I soldered on a lot of little blue LEDs, and I added some rhinestones for flair. Then I waited for it to rain, and I took it outside . . .  

Rain Umbrella

And waited . . . 

Rain Umbrella

And it worked! I love that it's possible to make an environment-responsive circuit with something as simple as copper tape, raindrops, and LEDs. It makes you wonder what else is possible . . . 


toy taxidermy

One way to construct knowledge is by deconstructing something to see how it works, and one of our favorite things to take apart in the Tinkering Studio is mechanical toys. There are some really interesting mechanisms inside, and it's a great way to play around with and learn about circuits. One thing that has always bugged me, though, is what to do with the toy after you've taken it apart. After all, that's where it really starts to get interesting. It might be because I'm from Texas, where taxidermy is pretty common, but I thought that might be a good (if slightly twisted) way to display the inner workings of a mechanical toy. 


Toy taxidermy



Stop Motion Deconstruction

Dan Riles, a participant in our Coursera class - Fundamentals of Tinkering, created this nice little stop motion animation that shows how he deconstructed his prehistoric Goodwill find.

He remixed the innards into something new:

We think of taking something apart as a tinkering rite of passage and Toy Take Apart in particular is a Tinkering Studio favorite.  If you haven't tried it yourself - What are you waiting for?  Grab a battery operated toy and get going!


Copper Tape & Conductive Thread

One of my favorite parts of working in the Tinkering Studio is the challenge of hunting down all the quirky, weird, and sometimes hard-to-find materials we use for activities and prototyping. As Materials-Nerd-in-Chief I often try to find several different sources for materials since items from different vendors will have varying strengths and weaknesses. Two materials we frequently get questions about are copper tape and conductive thread. Here's a quick summary of a few types we've tried and their pros and cons.


Copper Tape

Copper tape is a material we discovered during Jie Qi's residence with us a few years ago. She introduced us to it for making paper circuits, although it has all sorts of other uses, including keeping snails off your potted plants! 

JVCC tapeJVCC Copper Tape from Amazon.com (link)
This is my favorite copper tape to order for two main reasons. As some background, we cut all our 1/4" copper tape in half down to 1/8" wide for use on the floor. We get twice as much from each roll and the thinner strands are easier to bend and curve when desiging circuits. I love this tape because, first, when you cut it in half the protective backing stays stuck on, and second, because the cut edge is less sharp than other brands of tape. The biggest downside of this tape is the price, but it's worth it for visitor safety. 


sparkfun tape Copper Tape - 5mm from Sparkfun.com (link)

This copper tape is a great value and works really well. My only downsides for it are the slightly sharper edges and that the protective backing comes off more easily (both happen only when cut lengthwise). Using a bone folder or popsicle stick to press down the copper tape solves the sharp edge issue.


slug tape Corry's Slug & Snail Tape from Amazon.com (link)

This tape is great because you can find it at your local hardware store. It's inexpensive and because it's thicker (about 1.5" wide) you can cut it into interesting shapes (although for us, that means a LOT of prep work to get it ready to use on the floor). 


Conductive Thread

We love using conductive thread for making sewn circuits. Most threads are made of either silver or stainless steel woven with other non-conductive fibers. Stainless steel is better for durability over time becasue it's more tarnish resistant and silver is generally better for higher conductivity and better thread texture.

lame lifesaverLamé Lifesaver (link)

This is my all-time favorite thread for making sewn circuits. It sews most like traditional threads, is durable, and is highly conductive. Even though it's silver, we haven't had any issues with tarnishing yet. Truly, the only downside of this thread is that the ordering interface is a little cumbersome. 


sparkfun thinConductive Thread (Thin) - 50' from Sparkfun.com (link)

This thread is a great place to start if you're curious about sewn circuits and are already ordering other materials from Sparkfun. Generally it sews nicely, but can get tangled into itself at times. It also has a slippery feel which can make it hard to knot.  It's very conductive and is a good value thread. 


sparkfun cone Conductive Thread - 60g (Stainless Steel) from Sparkfun.com (link)
I ordered this thread for the first time when we were looking for something that we could solder to. It's tricky and takes some practice but is totally possible with this thread (others just shriveled up and burned away). It's fairly thick thread and, as mentioned in Sparkfun's description, has a slightly 'hairy' texture. 


less emfSilver Plated Nylon Bulk from LessEMF.com (link)
This was the first conductive thread we purchased for the Tinkering Studio. It sews more like traditional thread and can be loaded into some sewing machines. We've had a lot of success with this thread over the past few years, but lately we've had some spools that were 'duds' and not conductive. This is probably because they were older rolls that got tarnished over time.


I love to share resources for finding materials and enabling people to start tinkering at home, in schools, or in informal learning environments. Have a question about a material? Let us know! We may not always have the answer, but we're happy to share what we do know.