Yeah, if you tax the hamster too much, he probably won't like to run in the wheel. Hmm... this leads to an interesting question about the source impedance of a hamster...
I thought it was a widely known fact that one hamster has a source
impedance of 1 hamps. <chuckle>
On the more serious side, i noticed that in this thread it was stated
by the OP that the generator puts out 10 to 25ma, and the animal
runs for up to 4 hours a night.
Well, given the max of 25ma and 4 hours that totals up to 100maH
(one hundred milliampere hours) and so in order to get 8 hours of light
from a small white LED we can only drive the LED at a current of
100/8/1.4 milliamps, which comes out to almost 9ma. This includes
inefficiencies of NiCd cells, but a super cap would do better.
As far as switching on and off when the little guy runs, a single diode
might just be enough to handle this task using a dc generator.
The diode will only allow current flow from the generator to the
super cap or NiCd cells, with only a tiny loss.
The diode would connect with its anode to the generator plus (+)
output, and its cathode to the NiCd (+) terminal. Generator ground
to the negative of the NiCd cells.
There is some chance he might actually like having to try a little harder
to run in the wheel once the generator is connected. It may take
him some time to adjust however, and he might actually require more
food intake in order to put out the increased energy.
Should be interesting.
Once you get this going it is required that you post videos so we can
all see him run and make light