the cranked flashlight thread,
I have been tilting at this windmill : An "emergency light system" for the house based on white led's.
The power source for it, would be either hand-cranked, or a small battery driven motor culled from a VCR or some such, belted to the little generator. If battery driven, a circuit could be built to make the motor run and recharge the caps when the voltage goes low, and leds begin to dim a little.
This in turn would put the small generators' output - likely not much more than 4.5 useable volts, onto a bank of large scale capacitors, >> low volt 10K - 100K μF >> culled from wherever one can get them.
Base this on the fact that if you hitch your bench supply to a 3v dc motor, and include a large [ 100k ] cap in the circuit, after you disconnect the power supply, the capacitor continues to run that little motor for a good long time.
LED's draw far less current at the same voltage than a little hobby motor, so extrapolate this into a couple hundred K worth of capacitance, being drawn down by led's, properly hitched, led's shouldn't represent a dead short across the capacitors causing a catastrophic instant discharge when they are only charged to the limit of the generators output voltage.
Far from being a setup to produce "perpetual light" it should work for quite awhile, depending on how many leds you wire into the circuit...........
I have been tilting at this windmill : An "emergency light system" for the house based on white led's.
The power source for it, would be either hand-cranked, or a small battery driven motor culled from a VCR or some such, belted to the little generator. If battery driven, a circuit could be built to make the motor run and recharge the caps when the voltage goes low, and leds begin to dim a little.
This in turn would put the small generators' output - likely not much more than 4.5 useable volts, onto a bank of large scale capacitors, >> low volt 10K - 100K μF >> culled from wherever one can get them.
Base this on the fact that if you hitch your bench supply to a 3v dc motor, and include a large [ 100k ] cap in the circuit, after you disconnect the power supply, the capacitor continues to run that little motor for a good long time.
LED's draw far less current at the same voltage than a little hobby motor, so extrapolate this into a couple hundred K worth of capacitance, being drawn down by led's, properly hitched, led's shouldn't represent a dead short across the capacitors causing a catastrophic instant discharge when they are only charged to the limit of the generators output voltage.
Far from being a setup to produce "perpetual light" it should work for quite awhile, depending on how many leds you wire into the circuit...........