Replacing old 6v headlight bulb w/modern brighter bulb - Page 3

 
For what it is worth, I looked around for a DC:DC converter that would give
you 12V from the 6 at about 10A output.  Didn't find one (they all have
higher minimum input voltages).

Unless I missed an obvious product, looks like you're stuck with a 6V bulb.

Converting from 6V to 12V DC requires a device a bit more complicated than a
transformer.

 

Seems like you could almost do the whole electric
system with a device no more complicated than a
transformer if the bike was powered by an alternator.

Put a transformer between the alternator and the
rest of the bike and swap out 6 volt for 12 volt
horn and bulbs.

Lower amps at 12 volt so the wiring should carry
it. How you'd work the regulator I'm not so sure.

Probably not such a great idea and likely to let
all the smoke out but intriguing nonetheless.

 In article


The only problem is that the alternator is probably three-phase; this
makes finding the right transformer tricky. An alternative would be to
rewind the alternator with wire half the cross-section but twice as many
windings ... and then put in a new rectifier and voltage regulator.


Timberwoof <me at timberwoof dot com>
faq:  http://www.timberwoof.com/motorcycle/faq.shtml
Ten Steps to Fascism: http://www.guardian.co.uk/usa/story/0,,2064157,00.html

 
It has been many years since I studied 3-phase power, but I think you may be
able to make a competent 3-phase transformer using three single-phase
transformers where you connect the inputs in the obvious way (A/B, B/C, and
C/A), then connect one wire of each of the outputs together and use the
other 3 wires.

That is just a hunch.  I think that will give you 3-phase power at a
different voltage.

However, I don't know how you'd rectify the voltage.  With single-phase
power, a full-bridge rectifier and a capacitor will do it -- not sure what
to do with 3-phase.

 

Same way as before: the three coils of the alternator are either in a Y
with the center being ground or in a delta. Now consider the diode
bridge for an ordinary one-phase center-tapped transformer: basically
each outer end of the transformer has two diodes, one this way and one
that way. So you add two more diodes for the third leg of the Y. If it's
a delta, then it works the same way, only there's no "center tap".

--
Timberwoof <me at timberwoof dot com>
faq:  http://www.timberwoof.com/motorcycle/faq.shtml
Ten Steps to Fascism: http://www.guardian.co.uk/usa/story/0,,2064157,00.html