Modified Light Sign
As runner up for the “Red Bull Creation” challenge, we were given a sweet booth at the World Maker Faire in New York 2012. Red Bull made us some nice retro looking carnival signs with 50 incandescent bulbs surrounding the border. We made a quick video when we got it working. During filming 43 seconds in, Steve notices that a few connections were switched on the bottom, and we fixed it promptly. Even with the error in wiring, you can clearly see the nice effect this modification has!
How we did it:
We started with a simple plug in sign with all lights on. It was cool, but a little boring. We got back from Maker Faire, and we got to work on fixing that.
We quickly realized we had most of the supplies at our place already: An Arduino UNO and a Relay shield. We had been using the same relay shield to activate 12v winner lights on our spinning Centrifury game. We started by checking out the specs on the individual relays to see if they could take the load of the old fashioned bulbs. The 4 relays on the shield could handle 120v & 3A and could turn on the whole array when combined.
We had the idea of using simple persistence of vision. Wire every 4th bulb in a sequenced chain around the sign. To clarify, the actual wiring is done in parallel. This was the tedious part: lots of wire extensions, cutting, and combining. Our test program simply turned on one light at a time in sequence, leaving the other 3 off. When a sequence is completed, it gives the illusion of continuing down the chain as the loop starts over. Once we got that working, we switched directions for another effect. Then we added increasing/decreasing amounts of lit bulbs. For a final effect, we flashed all on/off in a slow strobe. Final connection of relays being done:
The relays should reliably handle 100,000 cycles. At the programmed rate, they will last for at least 48 hours! It’s great for short events, and relay boards aren’t that expensive.
We used the lazy man way of connecting due to time constraints. We still had blisters by the end from adding all of the extensions.
Here is the code for someone who wants to make something similar: RELAYtest
Thanks for reading!