A Mechanical Stopwatch Made of LEGO
A LEGO enthusiast built a mechanical stopwatch with four seven-segment displays that is accurate to 0.01 seconds.
If you are fully committed, almost anything can be built with LEGO bricks. Take YouTuber Banana Gear Studios’ seven-segment display, for instance, which was made with nothing more than LEGO bricks, gears, and a motor. But as impressive as that LEGO creation is, Banana Gear Studios recently decided to take it even further.
Way further. A set of four linked seven-segment displays were turned into a stopwatch. Not just any stopwatch — but one that measures down to hundredths of a second, is accurate to +/- 0.01 seconds, and rivals the precision of a phone. And amazingly, it is made entirely of LEGOs — although it does get some help from Mindstorms parts.
The seven-segment display was not originally built for high speed use, so to keep these modules from flying apart, Banana Gear Studios had some upgrading to do. He started by changing the gear design, which ultimately made it possible to flip the display 50 times per second.
That was only half as fast as the last digit needs to change, but Banana Gear Studios couldn’t eke out any more speed. Rather than resort to any “cheats” like gluing parts together, he just went with it. The final digit was modified to only show even numbers so it could run at half speed. This does impact accuracy a bit, but since it’s moving faster than the eye can detect anyway, it doesn’t make much difference, really.
With that worked out, the display itself was good to go. But there was still the not-so-small matter of flipping the digits at the exact right times. A motor alone couldn’t be tuned precisely enough to keep accurate time, so a Mindstorms programmable brick and motor were introduced for more precision. This was not entirely straightforward either, but with some trial and error, Banana Gear Studios eventually got the right formula worked out.
Testing the LEGO stopwatch by running it alongside a phone stopwatch and stopping them at the same time (or as close as possible with manual button presses) showed that the device worked exceptionally well. The result was often correct right down to the hundredth of a second — at least if the last digit was even, anyway.
Be sure to check out the video above to see how LEGO bricks can be transformed into a working stopwatch.