Our power for LED lighting, fiber-UTP media converter for the
Internet broad-band connection and the WLL phone comes from:
-
A small solar panel which we have mounted vertically on the south
wall, well in the shade during the summer months. The idea is to
use it mostly with diffused light. If we make do with the vastly
reduced power it generates, we are assured of a similar supply
even during the monsoons or when the sky is cloudy. So no fretting
over `today is a cloudy day..... '.
-
A pedal generator which you
see above - it generates about 28 W at
40 volts - enough to partially charge a 36 V lead-acid battery bank.
We have rigged up a half-horsepower induction motor with heavy
capacitors (70 μF) on the individual windings. These capacitors
allow enough tidal space for a small initial current (started due to
the residual permanent magnetism of the not-so-good core armature
steel) to start oscillating in the stator coils. These create fields
which energise the squirrel cage which in turn causes a cumulative
build-up of the whole process. Some of the induced current in the
stators is bled away via diodes to charge the battery bank. The
efficiency of the system is low, but we do not require any exotic
magnets like the notoriously scarce NdFeB. There are no
brushing contacts.
It seems that the solar panel is necessary - it is always better
to keep a small trickle charge on for battery protection. We have
tried with the pedal generator alone, but the batterys seem to
lose a lot and get damaged easily.
For the WLL phone, which runs on 5 Volts, we have used the buck-converter
IC from Recom, R7805-0.5. It will fail above 34 V input - so we use
a LM317 to reduce the voltage to a safe 30 V before the buck-converter
stage. The original battery of the phone has been replaced by a
4700 μF capacitor which is charged by the buck converter. It seems
to work just fine with very little loss.
