dave r
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| posted on 29/9/10 at 03:20 PM |
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moped headlight wiring
a mate of mine has an aprillia rs50
it keeps blowing headlight bulbs
had a quick look the other night, and its the type where the headlight is only on when the engine is running
is this circuit normally thru any sort of regulator? according to my meter, its also ac ?
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tony-devon
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| posted on 29/9/10 at 03:33 PM |
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sounds like the rec/regulator has gone?
normally you got AC coming out of the engine, then its converted to DC and regulated to max of 14.1vDC typically
it must have a battery for the leccy start, so thats probably screwed as well now 
heavy is good, heavy is reliable, and if it breaks, hit them with it
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Stott
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| posted on 29/9/10 at 04:21 PM |
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If it's anything like my KTMs were then the lighting supply is regulated but not rectified so it is AC.
DC is rectified out onto the other half of the system for ignition/CDI
If the bulb is brightening/dimming, or rather, really brightening, when revs are increased then the reg will be gone. It will be one unit (reg/rec) as
stated above but as I said the lighting feed is right to be AC.
All the best
Stott
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dave r
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| posted on 29/9/10 at 05:04 PM |
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didnt notice any voltage change with reving the engine.... maybe he has bought a couple of bad bulbs (cheap)
I'd love to give my imaginary friend a great big hug,
but this jacket makes it impossible.
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tony-devon
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| posted on 29/9/10 at 06:18 PM |
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blimey I never knew that?
learn something new every day
does he need a different bulb then for the AC supply?
intrigued now LOL
heavy is good, heavy is reliable, and if it breaks, hit them with it
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Stott
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| posted on 30/9/10 at 12:19 AM |
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No as a bulb is just a filament current flows in each direction at a given frequency warming it and giving light, just as in our houses, which are
ac.
The electrical principles are identical in that the filament presents a resistance to the supply, when current flows, it heats up and produces light.
It doesn't matter if this is ac or dc in this application, it's a simple device. In our homes, in reality the current changes direction
50-or so times a second, so the glow-dim-glow-dim-glow cycle is inpercievable by the human eye.
I only found out that motorcycle headlamps were ac (and out of a separate part of the reg/rec) when I bought a HID conversion for it and it
wouldn't fire when I started the bike.
I ended up installing a battery on it and changing the reg for a trail tech one, doing a full DC conversion on it, just to get a bright headlamp to
chase the RAC rally around the Welsh mountains. Worth it though!
In fact I'd recommend it, to all you enduro riders, buy a H4 HID kit halves with a mate(4800K so it's not blue) then do a dc conversion
with the trail tech reg, awesome lighting for about £70! 
EDIT: sorry for the school lesson, just explaining y'know!
[Edited on 30/9/10 by Stott]
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