Winging it

(* in the M50 category) So. On the Bad Boy running podcast they mentioned a 1 mile run called the " Killer Mile " running up Mow Cop in Staffordshire, a famous hill that hits a 25% incline in places. They had been given a place, did anyone want to do it? Well, duh, obviously! That's my kind of thing! The place was offered on the condition that there was some fancy dress element involved - details to be decided later. Hah. Costume? I can do costume... As it turned out the podcast were as useless and disorganised, as always, and didn't actually come up with any suggestions, so I used my imagination... and went for... Caffeine Bandit. Caffeine Bandit Only later did I actually figure out this event was happening on a Thursday evening, OK, that's a long way to go for just a mile race! So I came up with a plan, go up with Hugo, do the mile, head over into the Peak District, then we could spend the weekend running around, up the Pennine way etc, then head back to Surrey...

After the last tinkering with CO ₂  sensors on the VO₂ max device, Sensirion released an updated chip the STC31-C with finer resolution (0.2% vs 0.5%) and a more "raw" reading mode. The idea had been to use the CO₂ sensor to calculate the respiratory quotient, the VO₂ max device uses the O₂ sensor primarily to determine consumed oxygen. The O₂ sensor appears to be more accurate, reliable and consistent than the CO₂ sensors, however being electro-chemical, the O₂ sensors have a fixed lifespan. So the other idea is to see if it's possible to calculate the VO₂ max based on the expired CO₂ volume instead. The initial attempts had used the SCD30 sensor, however, despite being ridiculously accurate these sensors can only read up to 4% CO₂ levels, well below expired breath CO₂ levels and no use for exercise levels. So I ordered a few of the new STC31-C  to play with and built up a new module to test. PCB with an STC CO₂ sensor and SHT temp sen...

Following on from the last post  which was about the process and building, this is just an overview of the latest design. The kicad project files along with the schematic , layout , and BOM can all be found on github . The future Firstly, and I think I've expressed these comments before - but I'm still absolutely dumbfounded that the software and facilities are available for a basic hobbyist to be able to design and create something like this now. Yes it wasn't simple and took a while, but still, a few years ago this would have been impossible/unthinkable. New new design This is the new design. I spent some more time tidying up and redesigned the charger module again since the original one was too basic/primitive. The new new There are quite a few changes and improvements on this new design.  USB connection I changed to a USB-C connector, and the USB connection can be switched between the NRF and BG96 chips, most of the time the NRF will be useful but if you need/want to d...

 After the success of " Tracker Two " I decided, as I mentioned at the end of that previous write up, that it was time to see if I could build my own custom hardware. How hard could it be? 🤷 Evolution Version 0 For version zero of the tracker I tried using off the shelf 'personal tracking' devices, this proved that it was possible to build my own tracking site. Initially I thought I really didn't want to spend any time trying to build my own device, but inevitably concluded that was the solution. Version 1 The first incarnation of the custom tracker was the klutzy A9G based system  - well it wasn't klutzy at first, but after several iterations and enhancements it ended up that way. The A9G was incredibly cheap and worked reasonably well, but the module has some major design flaws and it can't do bluetooth (hence the klutzing). Version 2 The second version switched to using the RAK5010 based board , again it started elegant and ended up with multiple impr...

Testing the first version I constructed the VO 2 max device when I first heard about it on Instructables it was great fun to make and I was really impressed with the quality of design and construction. (I ordered the case parts from an online 3D printing service) All the bits The resulting unit is really professional and fun to use. The finished device I played with the code and made a few tweaks to the software, then saw there were some improvements and modifications that Ulli Rissel had worked on and incorporated those first incorporating a barometer (BMP180) then adding in a CO 2 sensor (SCD30) Since the device relies on calculating gas volume changes it seemed to make sense to include these sensors. I played with the project occasionally although frequently getting distracted by other projects (like my GPS telemetry tracker). After being contacted by Nik Hawks aka "Gristle King" who was also making his own version and improvements to the design (link: GristleKing ) thi...