One Moving Needle Holds the Hours, Days, and Seconds on This Digital Watch with No Screen

Wearing this watch provides an initial feeling of surprise, as a single needle glides across a printed scale to reveal the exact time or date without a flashing screen or ticking hands. Sahko transformed an idea drawn years ago into a polished item that fits easily around the wrist and seems both old and new at the same time. He desired a digital watch that depended solely on analog mechanics for display.

Early drawings depicted many scales crammed onto a single dial, each controlled by a button on the housing. He then built numerous prototypes to test different housings and circuits. The first version included a compass, which was a complete failure because the meter’s own magnetic field continuously threw off the readings. The functionality was then entirely dropped in favor of simplifying the design and ensuring that everything actually worked correctly.

The meter movement is simply a salvaged 1970s amplifier component that lies in the middle of the entire setup. A current flows through the coil and interacts with a magnet, swinging the needle left and right in a smooth motion. The Raspberry Pi Pico microprocessor turns time into voltage, which is then passed to the digital-to-analog converter and, last, to the meter coil, ensuring that the needle always lands exactly on the mark. They use the same needle and arc in all modes, but the information shown differs depending on which button you press.

The Pico, converter, battery, and charging circuit are all housed on a customized board that takes up little space. Sahko had the idea of printing the dial scales directly onto the board, making it incredibly durable and visually beautiful. On one side of the case, there are three buttons: one to cycle through the hours, one for the day of the month, and one to show the month or day of the week. Holding the proper combination causes the needle to sweep over the scale, marking off each second in real time.

The case is machined from aluminum and has a smooth matte texture from bead blasting, making it fingerprint-resistant and comfortable against the skin. You can even put a pocket watch-style cover on the dial to protect the needle and keep it looking good. The wire spacers keep the needle perfectly level, so it never scrapes the underlying surface. The strap is made of leather and features an elastic bit in the center for easy adjusting. The leather ends simply attach to the case via magnets, making them exceedingly easy to put on and take off without the use of traditional pins or buckles.

Power comes from a little rechargeable battery that can easily last the entire day. The casing includes a USB-C socket for charging, and the Pico’s programming does an excellent job of keeping the time accurate and determining which voltage range to map each reading to, ensuring that the needle always reacts swiftly. If you want to see the schematics of the whole thing, Sahko has even uploaded a set of files to GitHub that contain schematics, board designs, and the actual firmware.
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