As CuriousMarc’s video under reveals, in 1976 Texas Devices premiered their LED watch, taking such know-how from an costly oddity to one thing that may very well be extensively carried out. Per the restricted electronics of the day, the know-how behind the precise LED show unit is sort of attention-grabbing, that includes small LEDs, with a “bubble” magnifying lens over every digit and segments fashioned with tiny gentle pipes.
After discovering the chip that powered this watch, the TI AC5948N, throughout a restore, Marc set to work establishing a timepiece with it and a bubble LED show. Relatively than rigorously designing some form of watch housing, he merely soldered elements collectively immediately. The chip itself is used as the bottom of the design, with a coin-cell battery glued to the underside. For consumer interface, pushbuttons straddle the chip, and attachments are made with a mixture of wire wrapping and soldering. The ensuing timepiece seems to be nice along with his assortment of different oddball clocks.
Whereas it’s pretty easy connections-wise, the large problem was getting the voltage ranges appropriate. Because it seems, the CR2032 battery provides an excessive amount of voltage for chip-happiness. After some experimentation, Marc was capable of get it functioning correctly by including a diode in sequence with the set pin, dropping the voltage to the right vary. It is a enjoyable construct and one thing to remember when you discover an AC5948N within the wild!