Making an IBM PC real-time clock chip replacement

tebl on GitHub posts a circuit that can replace a Dallas DS12887 real-time clock chip in a vintage IBM PC or compatible. DS12887s had an integrated battery that is long past its usable date.

(A replacement may be made with) a Dallas DS12885, a 32.768Khz crystal (3x8mm, 6pf if you’re lucky enough to find one with a datasheet) as well as a CR2032 battery holder. Assembly is easy – all you need is to put the PCB on top of your chip, then bend up and over any pins that have a corresponding solder pad on the top. Solder it in place, add crystal and wire the battery holder leads in the indicated places.

The printed circuit board files and details are on GitHub.


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