Casio FW-91 replaced with smart internals
(crowdsupply.com)68 points by sponno 3 days ago
68 points by sponno 3 days ago
I agree with your points.
Where are you getting a genuine F91-W for 5€? A replacement 71604002 band costs me €8!
They do, albeit without a heart rate monitor.
https://www.casio.com/us/watches/casio/product.ABL-100WE-1A/
With a heart rate monitor it's considerably more expensive.
I respect these developers spending months and months to do something really not necessary and just for fun. I doubt they would make millions selling this so it is purely for their entertainment. I hope to find a hobby project to dedicate myself like these people one day.
Bluetooth could have such a tiny power draw if they would just have lower update rates.
I don't see any reason things like watches and tracking tags in some couldn't have 10yr life on a coin cell, or like 30 years with an LTO you charge monthly.
Deep sleep currents can be in the nanoseconds, and we only need power for a few milliseconds every minute to transmit an "I'm here" beacon.
Step counts and heart rates are different, but even that can be optimized a lot if you don't need 100% perfect data
If you missed this detail, they've also designed a replacement LCD which adds a few carefully-chosen segments and symbols. The end result still looks very similar to a stock watch, but is much more flexible: https://www.crowdsupply.com/oddly-specific-objects/sensor-wa...
This is sensorwatch.com and it is nice. It has been around for a while.
I get the fun part of engineering this but can't put aside that it doesn't bring that much new feature, a thermometer, international time, more advanced chronometer. That's all thing that I don't really care about.
On the downside, you loose the cheap aspect of this watch and the battery life is divided by 7. From 7 years to supposedly a full year.
I buy a f91w because it cost less than 5€ and I don't care to break it or get it stolen.