[Anarch157a]

You can scavenge car's alternators and use a water wheel or windmill to turn it. Alternators can work for a decade with minimum maintenance. Just have five or six stashed, just in case. They can supply 40A at 12V, or using a transformer to up the voltage, 4A at 120V.

[throwaway316943]

Have you successfully run any modern hardware off of the irregular current coming out of something like that? You could charge batteries off of an alternator with a voltage regulator but I doubt any modern electronics are going to work well on current supplied by a jerry rigged water wheel and step up transformer. You’d be reliant on a lot of ICs to do it properly at a small scale.

[cturner]

Would it be viable to use a rig of leyden jars to smooth out power coming from a scrappy alternator/commutator, and to implement cut-outs?

[emteycz]

Alternators are also trivial to build by hand.

[mauvehaus]

Sure. If you have the input materials. If you're at the point of having to build an alternator by hand rather than just taking one off a car, I'd like to know where you're getting magnet wire, the machined shaft, the various rotor and stator parts, the end-bells, and the ball bearings.

[emteycz]

Consider that you're not necessarily building from raw materials, you will be repurposing things you find around. Finding an alternator probably won't be a problem in the populated areas of USA but might be elsewhere - thankfully building it is still sufficiently simple.