STEAM Carnival Countdown Clock

Steam Carnival Countdown
The STEAM Carnival is coming up October 25 & 26th at the Port of Los Angeles. Two Bit Circus wanted a sign for the outside of the venue that would both tell how many days were left and grab people’s attention. Since it had to be daylight visible I suggested we use electromechanical flip displays.

Alfa-Zeta sells 7-segment displays that are perfect for the job. They’re 18″ tall and use an electromagnet on each segment to flip it between blank and white. We got 3 modules and their individual controllers. The controllers have an RS-485 interface and a pair of mosfets for each segment and another line that controls the polarity of the pulse to flip the segment. I used a DS1307 realtime clock module, a Teensy, and an RS-485 transceiver to drive the displays. The clock module isn’t really necessary since the Teensy has provisions to add a crystal and battery to use the internal clock.


The serial protocol supports two different modes. One lets you send characters to the display, the other lets you use binary numbers to represent which segments are flipped. I had the display show the number of days left until The STEAM Carnival but every 20 minutes it will display a random sequence to grab people’s attention. The display makes a delightful clatter. My coworkers Miya and Gretchen did the awesome design that wraps the display. Come see it at the Carnival. Use the Promo 5OFF to save $5.

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