dimming LEDs

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mew905

mew905

New Member
Sep 24, 2012
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Moose Jaw
I'm looking to build my own LED tail lights for my bike due to the ones that I bought are workable, but fragile (and the turn signals on them are hard to use and activate the horn which is annoying to say the least)

My question is if I get a 12v or 6v (I'm not sure yet) mini gen and convert it to equivalent DC power, how would I go about dimming LEDs to use as running lights? I *could* just run 1/2 of the LED's to simulate dimming but I'd prefer to actually dim them.

So the question is Is it voltage, or amperage, that dims an LED light? And does a resistor modify voltage, or amperage? I cant remember haha.
 
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bigbutterbean

Active Member
Jan 31, 2011
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Lebanon, PA
I would get whichever voltage generator you like and get led bulbs to match that for your taillight, as well as a rectifier and maybe a regulator. Tail lights can NEVER be too bright, so I dont know why you would want to dim them. My advice? ditch the cheapo plastic turn signals. No offense. Had two sets myself and the quality just isnt there. I think they would be fine for a pedal bike, but they just dont stand up to the abuse of being on a motorbike. Alternatively to the min-gen, you could just get a cheapo safety blinker on amazon for 3 or 4 bucks. Thats what I did, except I have 3. One for a tail light and two for side safety lights. I did also make my own brake light using an old yamaha turn signal, an led bulb from a flashlight, and a 7.2v nicad from an r/c car. I can go into more detail about the brake light if you like.
 
mew905

mew905

New Member
Sep 24, 2012
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Moose Jaw
I want to dim them to make them running lights and go full brightness when I hit the brakes. I'll be using dual color LED's (red/green, because Red + green = yellow) for the turn signals, but that's a different subject. I just need to be able to run the LED's a bit dimmer for running lights and I can come up with the mechanism to do brake lights.
 
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bigbutterbean

Active Member
Jan 31, 2011
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Lebanon, PA
Oh. The way motorcycles accomplish this is by putting two light bulbs in one housing. One bulb is constant for tail light, the other bulb activates when the brake lever is squeezed, making the light brighter to signal for braking. I have a separate tail light and brake light.
 
Greybeard

Greybeard

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Feb 8, 2011
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Sequim WA
rohmell said:
Best way to dim LEDs is by PWM.
Click to expand...
Haven't tried this yet, but it's kinda a pwm. I have an old Schwinn tail/brake light on my HD/Solex powered bike. The light has a ball bearing that rolls forward in a trough and activates a brake light. The lighting source on the HD is 6v ac. Im planning using a retifier on the brake and just the ac input to the led when the brake isn't on. In theory, the led get twice as many pulses through the rectifier and should be somewhat brighter. Maybe
 
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