Hi. Can anyone tell me which red LED's are the brightest for a given current. As a little project I want to make a rear light for my bicycle and might as well use the 'best' LED's I can find. I'm totally confused by beam angles, Lux, Lumen, Candela etc. I'm not looking for suppliers address's etc, just general information. Many thanks for any help. Keith (London U.K.) Sorry if you get asked this ten times every day!
Best led for bike rear light
- Thread starter Keith Y
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The Bull LED (http://www.strobe.com/products.asp?id=89&view=product) seems to be one of the brightest bike tail lights available at the moment. You would need to figure out how to wire up an appropriate battery pack to it and how to mount it. It uses 3 Luxeon I LEDs and optics and is supposed to be visible from the back as well as the sides. There is a good thread on it here: http://www.bikeforums.net/showthread.php?t=202062&highlight=bull+led+taillight
Tritium
Enlightened
1 red/orange luxeon 3 puts out 190 lumens + (translated: excessively bright). It is ideal for a bike tail light that is VERY attention getting. One of these with a small reflector and a faceted lens is spectacular. At around 3 volts you can run it from 350ma to as much 1A+ if well heat sinked.
Thurmond
Thurmond
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Thanks for the fast replies, but what I really want to know is, what is the brightest light for the least current? (most efficient). How many discrete red LED's (and of what type) equal the brightness of a red Luxeon-1 for example. Many thanks again for any help.
Varroa
Newly Enlightened
I just bought some of these 5mm rec LEDs in 15,000 mcd and 25,000mcd (LINK). The 15k versions are only a slitely brighter than the LEDs in a brand new blinky I just bought but they are alot brighter than the 2- 5 year old blinkies I have. The 25k versions haven't come in yet but I am very anxious to see how bright they will be.
markus_i
Enlightened
Keith Y said:
Depends on how exact you want to know it, then there's no way past the manufacturer's specs. It would help a little if you told us what your 'given current' would be - LED efficiencies will vary with the current. In addition, the brightness of the bare LED is only one part of the picture - once you want to use the LED in real life, the final brightness of LED + any type of optics inside the viewing angle which is interesting for your application becomes much more interesting.
The two extremes will be more or less completely useless for your application: A LED laser is extremely bright, but will only illuminate a very tight angle. On the other hand, a bare lambertian LED will illuminate one half sphere, but the brightness in each part of the sphere is much less. In both cases, the visible emitting area is very small.
For practical purposes, my standard setup is now a single red luxeon with an elliptical Fraen optic (long axis mounted horizontally) inside a b&m Toplight XS case, run at 20..40 mA (way below maximum). That gives a bright red light (comparable to a car rear ligtht) which is focused where it's needed (wide in the horitzontal, narrow in the vertical), has some side visibility at night and has a visible emitting area of around 1" diameter.
Bye
Markus
Varroa
Newly Enlightened
markus_i said:
What type of batteries are you using on this light? Is it regulated, direct drive or resistored? I am interested in this idea and I would like to build myself something similar. Thanks
Maplin in the UK (www.maplin.co.uk and shops) stocks a 5mm red led that puts out more light per Watt than a red Luxeon, and as it is a 5mm led, it needs no additional optics and is easier to mount.
Order Code N49AT: Hyper Orange L-53SEC-H
Kingbright description: L-53SEC-H (this is Kingbright's old numbering system)
Viewing angle: 20°
Forward voltage: 2.5V
Forward current max.: 40mA
Reverse voltage max.: 5V
Wavelength @ peak : 630nm
Power dissipation PT: 150W (I suspect this should be mW)
Light output min.@ 20mA: 7000mcd
Light output typ.@ 20mA: 10000mcd
I bought a few, and the viewing angle and brightness are such that it is brighter wider than the supposedly wider N48AT
The hyper orange is pretty close to the European standard rad rear light red. - not as deep red as the US standard car rear light.
I used six of them in a dynamo powered rear light and it is amazingly bright.
You could by a cheap 2xAA led rear and replace whatever is in there with these.
Steve
Order Code N49AT: Hyper Orange L-53SEC-H
Kingbright description: L-53SEC-H (this is Kingbright's old numbering system)
Viewing angle: 20°
Forward voltage: 2.5V
Forward current max.: 40mA
Reverse voltage max.: 5V
Wavelength @ peak : 630nm
Power dissipation PT: 150W (I suspect this should be mW)
Light output min.@ 20mA: 7000mcd
Light output typ.@ 20mA: 10000mcd
I bought a few, and the viewing angle and brightness are such that it is brighter wider than the supposedly wider N48AT
The hyper orange is pretty close to the European standard rad rear light red. - not as deep red as the US standard car rear light.
I used six of them in a dynamo powered rear light and it is amazingly bright.
You could by a cheap 2xAA led rear and replace whatever is in there with these.
Steve
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Steve K
Flashlight Enthusiast
Always good to hear from Steve, aka Bandgap!
I did a quick look at the Mouser site, hoping to find these leds, but had no luck. Anyone know where these can be purchased in the US of A??
Steve, aka Steve K.
(not very clever at nicknames, eh?)
I did a quick look at the Mouser site, hoping to find these leds, but had no luck. Anyone know where these can be purchased in the US of A??
Steve, aka Steve K.
(not very clever at nicknames, eh?)
markus_i
Enlightened
Varroa said:
Hi Varroa,
no batteries at all ;-) . I'm using a circuit that is quite similar to the one described at www.enhydralutris.de: hub generator, bridge rectifier, one, two or three white LUX IIIs in series for the front light. The rear light is set in parallel to one of the white front LEDs and resistored to ~40 mA, which turns out to be around 20..40 Ohms (IIRC). For a standing light, add a Goldcap somewhere in parallel to the LED. For a battery setup, 2 AAs and a resistor should suffice.
Bye
Markus
