I am working on a design (weather sensing) whereby I have a fixed shaft and on that shaft is a platter that spins. There will be some sensing electronics and a RF transceiver mounted that must operate. The original consideration was to use batteries to power this, however I was thinking it would be possible to design in a dynamo/generator which would save introducing parts that require frequent replacement.
I was thinking that if a permanent magnet were installed in the shaft such that the magnet is in the center of the platter (i.e. the magnet passes through the center of the platter), then some coils could be mounted on the platter in a ring around the shaft/magnet, and as the platter rotated I would get pulses of current in the coils, which could then be rectified and smoothed the charge a rechargeable battery to keep everything running.
Does that sound reasonable? Does anyone have any experience on the realities of generator design? I have no idea where to start with the calculations on how powerful the magnet would need to be, how close the coils must be, or how thick and how many turns of wire would be necessary to generate the power needed. The circuit runs on 5V and I can calculate the maximum speed that the platter can rotate at, but beyond that I am not sure where to go, hence I am here.
Any input?