And don't forget that you have to balance the physical shape and arrangement of components and traces with frequency and surrounding components otherwise you've created a transmitter spewing out noise at tens of MHz.
Or the corollary: if you aren't careful you can receive radio signals that will corrupt your data.
Oh, you think your wire can handle the 0.5A your widget needs? Let me tell you about transients that spike to tens of amps for a few hundred nanoseconds. But it's okay, that problem can be solved with a bit of trigonometry.
On the plus side, if you forget to connect your ADC to something, you now have a surprisingly decent random number source.
I love the absolute chaotic insanity of electronics. On the surface things make sense, but one level deeper and nothing makes sense. If you go further than that, at the bottom you'll find beautiful and pure physics and everything makes sense again.
I feel the same way about software. It's a hot mess, but under everything there's this little clockwork machine that simply reads some bits, then flips some other bits based on a comparison to another set of bits. There's no magic, just pure logic. I find it a very beautiful concept.
