It is possible to wire up the std 12volt ac regulator to a mini bridge rectifier wired in paralell, to then charge a battery which you can then use for your dc supply, I have done this on about 30 or more Lambrettas and a couple of small frame vespas. Using a mini bridge rectifier, the ac connections on the rectifier (mini bridge) are not used.
The negative connection of the mini bridge is wired to the regulator (from the same connection that feeds the loom with power).
The positive from the mini bridge terminal is connected to the battery's positive connection, then the battery's negative is connected through a fuse to earth.
This will give the battery a charging current of about 2 amp hour, under normal use. From what would be termed a "half wave rectified supply". I use this set up as its very cheep reliable and simple, as the ac is already regulated to about 14.6 volts all thats needed is a circuit that turns the ac supply into a dc current, which the rectifier (mini bridge rectifier) does.
Mini bridge rectifiers are available from about £5, and claim to handle current up 35 amps. and up to 400 volts. signified by markings on the side 35/400 these are available from Maplins, and this is the one I use and have used on my GP for the last 11 years, I must admit I have managed to boil the battery when on a Euro rally due to too many revs for too long, over charging the battery. This is not the fault of the rectifier but more the ac regulator supplying too high a voltage at prolonged high revs. I also run this system on my SX and the battery is now 7 years old and still working, but this is a 12volt 7amp sealed battery, much better quality than the Lambretta Item. I hope this little bit of info is of some help to anyone looking for some dc power from standard 12 volt ac system as fitted to all Indian electronic SIL systems....
