Dr. Scott Baker Goes Back in Time with a Raspberry Pi-Powered Hayes Chronograph Replica Build
Having failed to find an original for sale, Dr. Baker decides to create his own serial-connected stackable real-time clock box.
Maker and retro electronics enthusiast Dr. Scott M. Baker has published a clock build with a difference: It's a remake of the long-out-of-production Hayes Stack Chronograph, originally designed to fit in with the company's better-known modem products and provide real-time clock functionality to desktop computers without one fitted internally.
"I always wanted a Hayes Chronograph," Baker explains, "but I seem to miss the opportunity to acquire one, every time the opportunity presents itself. So I decided that in 2020 I would just have one … or else. A raspberry pi, a GPS, a 3D printed case, and an old soviet vacuum fluorescent display tube combine to finally yield me my Hayes Chronograph."
Originally developed in the 1980s, the Hayes Stack Chronograph was designed — as the name implies — to be stacked with one or more of the company's modem products. The device was more than a mere desk clock, too: While the front-facing vacuum fluorescent display (VFD) did indeed show both the item and day of the week, a serial port at the back enabled the Chronograph to act as a real-time clock for machines which lacked internal timekeeping hardware.
While Baker's recreation is a match aesthetically, its internals couldn't be more different to the original. While a vintage Soviet IV-28B VFD panel provides an era-appropriate display, the internals are a major upgrade: "To drive this display, I Googled around a bit and eventually settled on the MAX6921. That brings us to the brains of the clock," Baker notes, "a Raspberry Pi.
"Again, we’re going for 1980s look and feel but with 2020 convenience, and a Raspberry Pi is pretty damn convenient. It’s able to keep up with the data rate necessary to multiplex the display, while still allow such modern conveniences as the ability to login via SSH and program it.
"Finally, the clock needs a … clock. I had two options — 1) going with a battery-backed clock IC like the Dallas 1302, or 2) using a GPS for automatic time setting. I decided to design both of these options into the board, but populate only the GPS option. Having the clock be able to set itself, and having the superior accuracy that comes from GPS synchronization is pretty nice."
Baker's full write-up, which includes imagery of the replica 3D-printed case, can be found on his website; the source code, meanwhile, is available on GitHub.