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Old 03-19-08, 04:37 PM   #1
sffuji
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Bulbs for Generator Lights

Does anybody know where I can find 6V/2A bulbs for my old generator lights?
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Old 03-20-08, 03:53 PM   #2
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Are you sure it uses 2 amp bulbs? Most dynamo or generator lights use a 6V 2.4 watt bulb with a .6 watt taillight or a 6 volt 3 watt bulb without a taillight connected.

A well stocked bike shop will have them or visit a few large online bike shops that stock them.
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Old 03-20-08, 03:58 PM   #3
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Anybody hook up an LED light to a generator?
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Old 03-20-08, 04:33 PM   #4
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lumotec makes LEDs that hook up to dynohubs.

also you can get replacement bulbs from sheldon's shop, harris cyclery (link)
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Old 03-20-08, 04:46 PM   #5
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Anybody hook up an LED light to a generator?
Not yet, but you would need a full wave rectifier and a capacitor to turn the ac output of the generator to steady DC that the LED could use. You would also need a current limiting resistor for the LED. Depending on the voltage output, you may also need a voltage regulator.

This circuit looks interesting, but may be too complicated for some to tackle themselves:
http://www.elecfree.com/electronic/r...ynamo-bicycle/

But it handles recharging NiMH batteries and the LED light and looks like it would be just perfect.

Here is another design:
http://www.gobike.org/feat_lights.php
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Old 03-21-08, 08:35 AM   #6
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Dynamo-Powered LED Light Circuits for Bicycles.
http://www.pilom.com/BicycleElectron...moCircuits.htm


My circuit and the description. My new LED headlight and USB dynamo circuit.
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Old 03-21-08, 04:21 PM   #7
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I assume you mean the common 6V 3W halogens that are common for generator systems that are not powering a taillight. An expensive solution would be to order direct from the UK at reflectalite.

Depending on whether your generator's output is DC or not, you can go with various LED conversions as well. I'm not that familiar with generator systems. Do they tend to be DC, or AC? Also, are they constant voltage, or constant current (what happens when you go too fast?)

FWIW, I have two 6V 2.4W halogen bulbs I'd gladly sell for $5 a piece, $8 for both.
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Old 03-22-08, 07:26 AM   #8
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Do they tend to be DC, or AC? Also, are they constant voltage, or constant current (what happens when you go too fast?)
The German government in the 1950's set the requirement that all bicycle dynamo lighting systems be 6-volts AC 3-watts. Everyone followed this standard with with few exceptions. It's still with us today. A bicycle dynamo is an exceptionally simple device consisting of a rotating magnet and 4 or 8 poles made of layers of thin steel with a coil of fine gage magnet wire. Hub dynamos typically have 28 coils and 28 magnets. There are no brushes so there extremely reliable. All tire driven dynamos are sealed and not serviceable. There's nothing in them that you can repair anyway considering how little they cost to replace. Dynamos appear to be constant current devices in that current is limited by design to about 500mA. Voltage varies with speed. Quality dynamo systems include Zener diodes to prevent high voltage when the bicycle is traveling at high speeds from burning out the filament in old style bulbs. Modern LED lights do not need high voltage protection. New high power LED's from Cree and SSC can sink 1,000mA or about twice the maximum current a standard dynamo can produce. Until about a year ago dynamo lighting systems utilizing standard or halogen bulbs were considered inferior to battery powered systems. This is no longer true. A Cree or SSC LED used with good optics can produce as much or more light than battery powered systems costing hundreds of dollars.

Last edited by n4zou; 03-22-08 at 07:35 AM.
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Old 03-23-08, 03:56 AM   #9
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Anybody hook up an LED light to a generator?
Yep.
See my dyno link in sig for state of the art in batteryless bike lighting.
Easy to build a good system.
...mounting lights is the hard part
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