I've tried to do some basic circuits, but I always strike the same issue: resistors. Most basic books just say "add this resistor here", meaning that whenever I've tried to make changes I either kill my circuits or don't give them enough power (you can have hours of fun debugging electronics when you have a dead circuit and you don't know it).
Is there a simple equation I'm missing somewhere? And perhaps more related, is this issue covered in one of these books?
There is a simple equation, Ohm's law. Resistors are usually there to drop voltage, but there isn't enough detail in the problem you're facing to know exactly what the answer should be.
I'm not very proficient in hardware, so I'm about as confused as you, but clarifying your question can help. I bought these books (not the plus bundle, though) and they explain things a lot, so there is a very nice explanation for what resistors do in them, and hopefully why they're used where they're used. I mean, for $2 or so, there's no question about it.
Ohm's law is a important starting point (and will explain a lot of the basics if you branch off from there search terms you don't know).
However, I think the biggest problem for why resistors / capacitors / inductors / transformers are confusing for people coming from a software background is that they tend to (a) have to do with power circuitry, (b) be backed by physics that are non-digital, & (c) be fundamentally parallel/functional in nature. So a lot of intuition we have about digital state wrt imperative languages makes analog power circuitry design / function seem bizarre.
If you're really curious, I'd try and find an introductory text to basic power circuitry design (good starting point: how to build a passive & active AC/DC transformer). Most of the components get used in that context and if you can understand them there then you can understand them anywhere.
Relatedly, I skimmed one of the Make books (the encyclopedia of parts, part 1), and it goes into some detail about how a transformer works, so that seems like a good starting point (for me as well), thanks.
Ohm's law is simple sure, but applying it hasn't been simple for me. In particular looking up data sheets and figuring out how to properly apply Ohms law to the circuit I want to put together.
One thing that usually isn't mentioned (at least in the projects I have seen) is the wattage of the resistors required. I can have a 200 ohm resistors in 0.25 watt rating or 1 watt rating or something else. Depending on what is required for your circuit it can burn your resister due to excessive current.
Very quickly regarding the topic of dead circuits. The first tool you want to always have with you is a digital multimeter. Anytime there is doubt, simply test the two ends of the component or circuit and you can very quickly "debug" the whole thing
Those basics knowledge are part of the first chapter of the Make Electronics book, and then afterward you'll get the full explanation about why chose this or this component. I can't vouch for them enough !
I've tried to do some basic circuits, but I always strike the same issue: resistors. Most basic books just say "add this resistor here", meaning that whenever I've tried to make changes I either kill my circuits or don't give them enough power (you can have hours of fun debugging electronics when you have a dead circuit and you don't know it).
Is there a simple equation I'm missing somewhere? And perhaps more related, is this issue covered in one of these books?