5 Minute Signal

For the past year and a half I (Mark) have been part of an Ann Arbor, Michigan based group named GO-Tech. The common thread among the group members is that each of us is interested in making things using technology (combining hardware, software, metal, wood, etc.). I refer to it as “Do It Yourself Tech” (DIYTech). The group meets monthly to present projects and have interesting discussions. I attend when I am able; it is a fun, enriching after hours activity.

At the most recent meeting that took place on January 13th, there was a contest in which everyone was invited to build a device and demonstrate it at the meeting. As Dale (the group organizer and leader) described it:

The Five-Minute Timer Contest goal is to design a timer to time presentations at our meetings. It should semi-accurately time the presenter, and give some audible or visual indication when their time is up. Portability, coolness, and robustness will be helpful. Cool prizes supplied by O’Reilly, publishers of Make.

I created a traffic signal based timer that I named “5 Minute Signal.” The time is actually settable to one minute and up (in one minute increments). To build it, I hacked an inexpensive plastic traffic signal (about one foot tall) that I purchased from Oriental Trading Company. To control the signal and provide accurate time keeping, I used my trusty Bare Bones Board (BBB) Arduino-compatible microcontroller board. The hardware is fairly simple (the BBB, a pushbutton control switch, and 3 relays to control the red, yellow, and green lights) and the software was fun to write. I put the whole thing together the weekend before the GO-Tech meeting.

Basic operation is as you would expect: Push the button to start the timer. When the time interval is set to 5 minutes, the green light will stay on for the first 4 minutes, followed by one minute of yellow, and then red at the end of 5 minutes (the green and yellow intervals are shorter when the interval is 2 minutes or less). More details are available in these documents:

The other contest entries included a very clever and well-made artificial sundial timer (by Jim) and another with a large servo-driven dial (by Don) that, if the presenter went too far over the allotted time, popped a balloon to get everyone’s attention. The meeting attendees voted and in the end I tied with the sundial for “Best Timer” and the sundial won the “Coolest Timer” award. I walked away with a copy of the Best of Instructables book (thanks O’Reilly).

There was one more 5 Minute Timer project presented at the meeting (it arrived too late for the contest). Peter put together a traffic signal based timer similar to mine that uses a full size (reclaimed) traffic signal that he purchased on eBay. His impressively polished project includes a wireless remote control (something I considered but did not have time to include), a custom printed circuit board, and a wooden project box. Schematic (PDF).

The meeting also included an interesting talk about EMC and some other presentations. Overall, it was a creative, fun and informative evening. If you are in the southeast Michigan area, I highly recommend that you attend an upcoming GO-Tech meeting