Most of us don’t ever need to know the exact time, down to the second. Heck, many of us would get by just fine as long as we could find the time within 10 minutes or so. But precise timekeeping is incredibly important for a wide range of scientific and technical endeavors. Beyond that, it can be cool to see the exact time with both extreme accuracy and precision. Six years ago, Tim Alex Jacobs (AKA “Mitxela”) built the Precision Clock Mk II-1/2 to achieve exactly that. Now he’s back with the Precision Clock Mk IV (don’t question the version number scheme).
The previous Precision Clock Mk II-1/2
The Precision Clock Mk II-1/2 was very impressive and could display the date and time down to the hundredth of a second, which is two decimal places after the seconds.
The new Precision Clock Mk IV
The Precision Clock MK IV is better by an order of magnitude, increasing precision to the thousandth of a second. It also has a few other tricks up its sleeve, including a folding frame, a flicker-free and jitter-free display, battery-powered and quartz-backed timekeeping, a more STM32 powerful microcontroller, and display precision that mirrors the clock’s actual accuracy.
That last feature is very interesting and not something I’ve seen before. In engineering, the number of significant digits is an indication of the precision or accuracy. If a technical drawing specifies a length of 52.00mm, you might have a corresponding tolerance of 0.01mm. If someone gives you a QA measurement of 52.0mm, it is safe to say that they didn’t use an instrument capable of the required precision. The Precision Clock Mk IV displays the time in a similar way, disabling the most significant digits if the current accuracy doesn’t match their precision.
The time, and that accuracy, comes from GPS. The clock’s GPS module lets it determine its location and therefore time zone, which is convenient. But more importantly, GPS satellites provide extremely precise time — something that is critical for accurate positioning. In the event of power loss, the clock will continue to keep pretty good time with a quartz crystal and watch battery.
Because the most significant digits increment so quickly, Jacobs also worked hard to eliminate all flickering and jitter. Flickering is a common problem for LEDs and it occurs because of the use of PWM (Pulse-Width Modulation) brightness control. PWM works by modulating power very quickly in order to lower the average voltage, resulting in less perceived brightness. But that modulation makes the LEDs flicker, which you’ll often notice while recording them with a camera. Jacobs solved that by controlling a voltage regulator with a DAC (Digital-to-Analog Converter), giving the LEDs true analog voltage for dimming.
The flicker-free display, combined with the high precision and accuracy, making the Precision Clock Mk IV genuinely useful for scientific purposes. Put the clock next to something while recording in high-speed or capturing a snapshot, and you’ll get a great in-frame timestamp.
Finally, the whole clock folds in half. That’s cool because it is very long in its normal configuration. Not only does the folding make transportation (and shipping) easier, but the clock still functions when folded. That means users can set it up in whichever of the two configurations they like best.
If you want a Precision Clock Mk IV, Jacobs is selling them on his personal shop. It is out of stock now, but you can sign up to receive an update when more are available. A kit costs £250 GBP, while a fully assembled clock costs £350 GBP.