The construction of the Derby Swissonic is different than anything you have seen so far. It reminds you of an old bedside flip clock, doesn’t it? In reality, it is an ingenious plastic speedometer “drum-machine” powered by a 7-jewel transistorized electromagnetic module.

7:55 on the Yema Digital

From jumping hours to jumping minutes

The Derby Swissonic might bring back fond memories of typical ’70s jump-hour wonder watches. They are available in tons of (mostly bulky) case designs. You can easily recognize them by two or three digital concentric discs showing hours, minutes, and seconds. As the Yema Digital video here shows, the minutes are usually constantly running, and only the hour jumps.

Derby Swissonic

Mitch Greenblatt, known for Horolovox and his book Retro Watches, introduces the Derby Swissonic as a driver’s watch housing the most awkward jump-minute movement devised for mass production. This movement is the ESA 9176 Dynotron, which belongs to the group of early transistorized watches with a balance wheel. It was introduced at the Basel Fair in 1974. Besides Derby watches, you can find versions by the French brand Jaz. The watches came in chromed or gold-plated versions with a semi-leather strap or a stainless steel bracelet. Pieter Doensen, the author of History of the Modern Wrist Watch, says Jaz offered them in six different case designs.

How the Derby Swissonic works

I found an amazing website that describes the Derby Swissonic in the tiniest details. Tons of pictures show what the naked Dynotron movement looks like. “The battery activates an electromagnetic coil which operates a balance wheel with permanent ferrite magnets, exactly the same way as in other transistorized watches. The rotating roller jewel on the balance moves an escapement wheel which transfers torque to a long metal rod on the drum-machine filled with a row of teflon-type gears.”

Derby Swissonic

“Corresponding gears move the seconds-drum, which gradually rotates/jumps the first minute-drum every 60 seconds, then the second minute-drum every 10 minutes, and all of the drums including the hour-drum every 60 minutes. The jumping functionality is obtained by means of a tiny and delicate spring installed permanently on a light-blue wheel combined with the seconds-drum. This ‘invisible’ spring is a major issue with these watches and results in 50% of malfunctions.”

Well, I guess I’d better not take the Derby Swissonic on a bike ride to the office.

Buying experience

Whatever book you open, you will read that the Derby Swissonic was a smart but shaggy invention, not only due to the use of plastic parts. The movement was also not tested sufficiently before it hit the market, which means that finding correctly operating Derby watches is not easy. “Plastic gears and the caseback might be broken if abused, especially if it has been screwed in too tightly, causing the movement to stop,” says the author of

Derby Swissonic

Buying a Derby Swissonic can be more painful than buying any other watch. I have a friend that has two Derby watches, but both need the same part to bring them to life. Careful due diligence and a real understanding of the weak points are essential when buying a Derby Swissonic, especially extensively worn ones. “It might be sold as working, although the electromagnetic motor-module might work alone after installing a battery, but the drum-machine will not advance the time. The easiest and very uncommon reason will be jammed gears, but the deeper we go, the more issues we might experience,” warns

Derby Swissonic

Wrist experience

Unless you sport a Girard-Perregaux Casquette 2.0 daily, you might find the Derby Swissonic a bit “hostile” on your wrist. I have to say, I’ve got a pretty crazy lineup that includes watches like the Toyota Orient Puma, but the Derby Swissonic is really challenging to wear. The hat-like side shape is pretty organic, but the frontal view gives more of a brick-like experience.

Derby Swissonic

I like that the crystal runs across the full width of the case. The rotating drums are sunken quite deep, but they are legible enough. I think that the apertures over the drums could be slightly bigger, but I guess the designers kept them so tight for a reason. They wanted to make it so you just see the current time and nothing else. No matter how hard you try, regardless of the viewing angle, you can’t spot the previous numeral or the next one on the minute drum. And that is pretty astonishing because it makes the jump-minute effect seem even more miraculous.

Last thoughts on the Derby Swissonic

If we can rightly call the visual experience “epic,” the same applies to the sound of the watch. I don’t remember a watch ticking this lively and loudly. If you combine it with the “clicking” jumping sound every 60 seconds, you almost feel like you have a minute repeater.

Derby Swissonic

By the way, when I photographed the watch, I put it on my desk randomly. I guess you won’t like this, but it looks so good resting on the table next to my computer. It really looks like a tiny desk clock. So if you are afraid of beating the life out of it on your wrist but you find it too cool to have it sit in your safe, there you go! Happy hunting.