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Squishy Circuit Bending

  • by Rebekah Nelson on July 8, 2014
    Have you ever heard of circuit bending? No? Neither had we before we developed our new Hands-On Science Workshop, Squishy Circuit Bending! In this exploratory workshop, inspired by the REBOOT:music exhibit, guests tinker with the insides of electronic devices to create new sounds or movements. These new sounds (or movements or light patterns) are called “bends.” Bends are created by connecting various parts of the circuit board with conductive material, creating short circuits that do cool things. Our conductive material of choice for this workshop is salt dough. 

    The recipe we use is an adaption of the Squishy Circuit Dough, developed by the University of St. Thomas’ Squishy Circuits Program. We love the accessibility of the dough (it’s nice and easy for little hands to manage), but most of all we love its variable resistance! Because the alignment of the salt ions changes everytime you touch the dough, you can play around with an huge range of resistance- just like if you were soldering potentiometers (knobs) onto your connections! 

    To make a batch of conductive dough at home you’ll need:

    1 cup hot water
    1 1/2 cups flour, reserving 1/2 cup
    1/4 cup salt
    3 Tbsp cream of tartar
    1 Tbsp oil

    Optional Ingredients:

    glitter, just for fun
    Kool-Aid packets, for scent and color 
         (As a kid, one of my favorite parts of making salt dough at home was getting to pick the “flavor.” But please, do not eat the conductive dough, no matter how nice it smells!)

    Making the Dough-

    1. In a large bowl, mix 1 cup of flour, salt, cream of tartar, Kool-Aid and glitter.
    2. Add the hot water and oil to the dry ingredients.
    3. Using a spoon, stir the mixture until the dough begins to clump up.
    4. Using your hands, begin to knead in the remaining flour. Be careful- the dough might be very hot! Let the dough cool down a bit until it is comfortable to work with. 
    5. Continue kneading and gradually adding flour until the dough reaches a soft, but not sticky, consistency. You may end up needing to add more than the reserved 1/2 cup of flour. We’ve had batches that need as much as a whole extra cup of flour!
    Now you have your conductive dough! When stored in an airtight container, the dough can last around two weeks or so before drying out.
    The next step is taking apart a toy. Good circuit bending candidates are sound generating, battery operated toys. NEVER ATTEMPT TO CIRCUIT BEND ANYTHING THAT PLUGS INTO A WALL. It is very dangerous! It’s also a good idea to use older toys that you aren’t attached to; circuit bending has the potential to permanently damage the preprogrammed functions of a toy. If you do plan to reassemble your toy after you’re done circuit bending, take lots of pictures as you disassemble the toy so you’ll remember how to put it back together. 
    Tools You May Need:

    various sized screwdrivers
    something to store all the screws in
         (We use magnetic dishes in the workshop!)
    hot glue gun and glue sticks
    safety glasses
    disposable gloves
         (Old toys can be pretty dirty inside!)
    Taking Apart Your Toy-
    1. Put on your safety glasses and gloves.
    2. Remove the batteries.
    3. Unscrew all the external screws.

    4. Carefully open the toy. Be gentle with the wires that connect the two pieces- those are usually the wire from the batteries! Warning: Fairly often, toy casings will be stuck together. If the toy halves are really stuck, check for any screws you may have missed. Sometimes they’ll be hiding under lables or in handles. 

    5. Check out the inside of the toy. If you can see the colored side of the circuit boards, great! If you can’t see the side with all the solder points, keep unscrewing. You can disassemble the entire inside if you want! Just keep in mind that the more taken-apart a toy is, the more fragile the circuits become. Without the plastic casing, it becomes really easy to accidentally pull a wire loose.

    6. Once you’re happy with the state of your toy, it’s time to do a little spark prevention. While sparks are fairly unlikely to be generated by connections made using the conductive dough, it is still a good idea to cover know hot-spots. Trace the wires from the battery holder to where they connect to the main circuit board. They may pass through a switch first, of so, follow the wires from the switch. 

    Once you've found the connection points on the circuit board, use a drop of hot glue to cover the connections. Hot glue is an insulator, which means electricity can’t pass through it.

    At this point, your toy is ready to circuit bend!
    Making Your Toy Last Longer-
    If you've really gone to town taking apart everything, or you just want to beef-up your toy’s connection points, use some hot glue to support all your wire connection points. Make a blob of glue around the base of the wires, and any other components that might bend repetitively.

    Circuit Bending Your Toy-
    1. Insert the batteries into the toy.
    2. Using some conductive dough, poke around the solder points on the circuit board until you find a fun effect. Sometimes having the toy actively making sounds as you bend helps. Try turning on any pre-programmed songs while you investigate with the dough. Don’t be discouraged if you don’t find a bend right away, some toys just take longer than others.

    Placing the dough on or around chip-on-boards, those black blobby things on the circuit board, usually produces interesting bends.

    Capacitors and resistors are also good spots to try.

    If at any point your toy stops making all sounds, it has probably shorted out. Which is no problem! Most of the time all the toy needs is a hard reset- which is just a fancy way of saying pull out the batteries then put them back in.
    And that’s it! Anyone can circuit bend with conductive dough! Have fun exploring your toys in new ways! And come join us at the Hands-On Science Workshop at the Tech!
    Rebekah Nelson is the Programs Development Lead at The Tech Museum of Innovation