My $0.02 as a response to several comments I read in this thread: I was diagnosed with ADHD in my 40s and got Concerta. My belief is that ADHD is not a disease, nor a disability (even though it acts like one very frequently) and in fact there is evidence that ADHD is an important part of our evolution as a species.

The problem(s) mostly relies with the modern way of life and what is expected from the society at large. In that context I try to feel ok when I daydream while I have countless of boring things to take care of as I totally feel ok when I hyperfocus in a creative endeavor.

The meds are just a tool that I use no more than two times per week in order to take better care of myself and others. It is not a therapy and it's not me. I believe that Sensitive Rejection Dysphoria is very real for people like us, but the worst version of it is when you reject yourself because you are different and you try hard to be someone else.

> The WHY2025 badge was designed to be powered by 2 Li-Ion 18650 battery cells connected in parallel.

Wait, what?

I was under the impression that Lithium batteries were really difficult to put in parallel without a LOT of engineering work.

The discharge curve for Lithium batteries is super flat. If you put them in parallel, even a small differential between the two means that one battery will completely discharge simply trying to bring the voltage of the other up to match. This is very different from the discharge curve from alkaline which has a nice slope and the batteries can equalize without burning up very much of their capacity.

These don't look like they're matched in any way. The connection between them doesn't like very big--I suspect a non-trivial voltage drop if one battery tries to empty into the other.

If you need the power, it's much better to put them in series and use a buck converter to bring the final value where you want it.

This seems more like a fundamental engineering flaw rather than a fault in the boards (although, to be fair, the creepage and clearance don't look great).

Wood expands and contracts with moisture content. More moisture makes the fibers "fatten up".

The interesting thing is that this is anisotropic: the expansion/contraction occurs across the grain, NOT along the grain. The rate of expansion also depends on the local characteristics of the grain itself (hence the effects of warping due to uneven expansion) ... Also there's a big difference between the direction "across the growth rings" (i.e. radially when it was still a tree) and tangentially to the growth rings. And these surfaces are curved, of course. But one thing we can always say is: the wood doesn't significantly change size along the grain.

Design and construction methods can make wooden artifacts more or less susceptible to cracking and distortion from this. For example dovetail joints can be pretty good as all the wood expands/contacts together the same way. Especially if the pieces are joined together from the same piece of wood. Stuff like that. Or at the other extreme, metal fixings like nails don't move with moisture at all, which can cause problems with relative movement and stress can accumulate.

Edit: and the repeated cycling of moisture content induced stress can eventually lead to cracking, in a similar way to metal fatigue. Old wood just cracks sometimes, this is probably why.