Making a dumb watch smarter

As a watch enthusiast, I feel like you almost have to own a Casio F-91W at some point. Mine never got that much wrist time, but I’ve always liked it for what it is: simple, ridiculously light, cheap and pretty much unchanged since 1989.

I’ve also always liked modifying watches. After building a Seiko mod before, I eventually came across the Ollee Watch One Kit, a replacement circuit board that gives the F-91W a surprisingly smart upgrade.

I’d had one on my radar for a while, so eventually I ordered it.

A new brain

The idea is simple. You keep the original case, LCD and buttons, but replace Casio’s original circuit board with the Ollee board.

That adds Bluetooth, automatic time syncing, step tracking, weather forecasts, multiple alarms, timers, temperature logging and quite a few other features. There’s even a heart-rate function using a pulsometer.

All while keeping the original F-91W display.

Fifteen minutes later

Installation was surprisingly easy. Four screws remove the backplate, the original board comes out and the Ollee takes its place. No soldering required.

I also put the included programmable NFC tag behind the LCD, which lets the watch trigger whatever NFC action I decide to give it.

After putting everything back together, I enabled Bluetooth, downloaded the Ollee app and paired the watch. About fifteen minutes after starting, my ordinary F-91W had become a deliberately dumb smartwatch.

Still an F-91W

That’s probably what I like most about it. It still looks and feels exactly like an F-91W. There’s no touchscreen, giant display or constant stream of notifications.

Instead, I can now look at the same tiny LCD Casio has been using since the eighties and somehow check a five-day weather forecast on it.

Battery life is still around ten months with normal use, so it doesn’t suddenly need charging every few days either.

It’s still tiny, simple and unmistakably an F-91W. It just does quite a bit more now.