LED Bubbles from the 1970s Tell the Time
By Al Williams
[CuriousMarc] is nothing if not curious. Finding some old TI timekeeping chips to reverse engineer, he set out to make a clock using old-fashioned “bubble LEDs.” You can see the result of his tinkering in the video below. For the uninitiated, bubble LEDs are 7-segment LEDs with magnifying bubbles over each digit. These were popular in calculators, watches, and other places that used LEDs before LCDs largely displaced them.
The history of these has to do with the power required to light an LED. You don’t technically need a magnifying lens, but larger LEDs take more power. These displays were relatively low power and used tiny LEDs with light pipes to make each dot a full segment. The lens made the segments larger and easier to see.
Beyond the TI chip and HP displays, there isn’t too much else needed. [Marc] just wired the whole thing using the IC as a substrate. Sort of dead bug construction using enameled wire. At first, it didn’t work but it turned out to be a battery issue. The device really wanted 2.5 V and not the 3 V provided by the battery. The solution required a little detective work.
We know this isn’t a very practical project, but we love seeing this old tech again and while the dead bug construction isn’t beautiful, there is something appealing about the look of it. Maybe one day people will build steampunk things and discopunk will be for the 1970s?
We’ve seen bubble LED projects before. If you want something more in a watch form factor, that exists, too.
January 11, 2022 at 01:00PM
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