sketchpad

Circuit Board Prototyping

21
Apr/15

Out classic design for circuit boards has worked well for many years. Some of the features of the set that we value are the natural wood blocks that feel approachable, the nails that make for easy connections with alligator clips, and the transparency of the simple battery packs, light bulbs, and switches. But with our current facilitation schedule, the activity set has to do more duty as a 'self-serve' activity. We think that this works okay in terms of the experience of visitors who can get started on their own and have a good time messing around with circuits, but it makes us think deeper about how the design can best support this role on the floor.

The Art of Tinkering Workshop – Day 1

The biggest thing that we've had to make adjustments for, is the possibility that the battery packs get left short circuited for a long time. We've learned that this can lead to batteries heating up, popping and creating a possibly hazardous experience. Once we started having the circuit boards out in the tinkering studio without constantly present facilitators (who can periodically check and unclip any short circuits) we needed to rethink and tweak the design.

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So over the course of six months or so, we tried lots of different things. First we experimented was a new covered battery pack. We started to test out this black one, but didn't like how you couldn't see the batteries. Finding a transparent battery pack solved that problem, but the plastic used in this piece was brittle and more likely to break, so that was out for the museum floor as well. Also, both of these packs had to be unscrewed to change the batteries which meant that explainers who have limited time might be less likely to change out dead batteries.

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Our next idea was to mount an acrylic cover to the board. This solved the transparency and sturdiness requirements, but made it much harder to change the batteries and we felt like having four screws to undo instead of one would make changing out dead batteries too onerous.

Battery heat from The Tinkering Studio on Vimeo.

We remembered about a year ago, we had been experimenting with resettable fuses in circuit boards. We ruled them out at the time because we didn't want to hide the piece, yet since it got really hot, having it exposed was also not a good option.

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But after going back over the design options, we came back around to the PTC and wondered if a simple clear acrylic cover would do the trick to prevent visitors from touching the hot part, yet keep the component visible. We put together a board and short circuited it for a while to test out how it worked. The battery didn't rise in temperature and the acrylic cover just got a little bit warm to the touch. So this seemed like a good solution.

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I built ten or twelve boards to make a test run on the floor to see how they held up (I also added a bit of a back stop to some of them to see if it would help with breakage). Everything seemed great, although it still felt a little odd to have a mysterious part on every battery pack. We're hoping that we can make a sign, maybe with an illustration from former artist-in-residence Iris Gottlieb, explaining how the component works and why it's there on the circuit board.

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On a brilliant suggestion from Wendy, one of the Field Trip Explainers, we started trying out rechargable batteries with the new set up. We had ruled those out before because something about the recharging made them more likely to explode when short circuited. But with the new system in place we could try them again.

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So by some amazing coincidence, today, on Earth Day, we started to test out what it would be like to have the rechargeable batteries in the Tinkering Studio with charging stations near by to switch out dead batteries as needed. We can't wait to see how this experiment works and are really excited to go green in the circuit workshop.

In addition to the battery pack refurb, we're starting to think of ways that the circuit boards set can be 'plussed' when faciliators are present in the space with interesting materials for homemade switches, more complex parts, and other ways of going deeper with the activity. We'll keep you posted on the next steps for evolving this venerable activity.

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