I have to say the presence sensor is nice for things like backpacks and purses, but when it comes to putting it on your keyring, the thing is huge!
I noticed it uses a CR2032 inside and that is taking up the majority of the board space. Around it, however, seems to be more plastic than is really necessary. I think if you went to a super durable plastic you could shrink the overall size by 1/3. Perhaps later on, moving to two CR1632’s side by side wired in parallel could take the size even smaller.
I’d be interesting in replacing the housing on the presence sensors.
@Ben any way to increase the polling times on these? 30 secs is causing the alarm to go off when someone opens the door before ST notices presence chance. Or maybe I’ll get a motion sensor plugged in to increase the range so it tracks it sooner.
@Ben, please consider offering the new enclosures (no guts) for a small price so current users can convert their existing ones to the new, smaller size. I might consider that. I could also see different versions of the enclosure. Maybe one that is magnetic, different colors to help identify them, etc. Given their different usage scenarios (keychain, pet collar, car, backpack/purse, etc), I can definitely imagine different form factors using all the same guts.
If you check the quick browse lists in the community – created wiki, in the project reports section look on the list for “animals” or “pets” projects. There are a couple that discuss dog collar options.
The least expensive receiver is likely to be some kind of raspberry pi, but that requires some technical skills to set up. @ogiewon or one of the other Maker type folks might be able to say more about this kind of hardware option.
The easiest would be a refurbished unlocked iPhone 5s operating only on Wi-Fi. But those are going to run about $120 each.