Need ideas.... (warning, about 1mb of photos)

fenix-store
Right, it worked and the photos do show up...

Anyway, I'm new here on the Candle Power Forum and hope to learn more about leds from all of your experiences.

The photos shown above is pretty much a normal cateye bike light without the cateye brand, and without the expensive price tag =)
It probably came off the same production line in china but the folks there just decided to run more off and sell them cheap.

So, to my main point. I'm interested in converting this to an led light. It has fitted space for 2 "C" cells, and quite a lot of extra room near the front half of the lamp.

There are a few things that are on my list at the moment:
1. How many leds am I gonna use? (And how long will they last?)
2. Will I need a step-up circuit?
3. Should I use the original reflector?
4. If I have a lot of leds, then maybe I can have white leds surrounding, say 3 blue ones. Then I can add a little switch to change to just 3 blue (for longer use) or lotsa white ones for brightness. Or should I bother?
5. Another idea is to mount hundreds of leds on the case of the light, thus effectively having a small "sun" attached to my bike blinding other people, and myself. (any excuse to wear my cool sunnies :cool: )

One thing I'm particularly interested in is the circuit in the Arc AAA that I've been reading about. Apparently it keeps the led burning at approx. constant brightness until the battery dies? Is it possible to homemake one, and possibly fit it in the lamp?

Anyway, thanks for wasting your time and brain power for reading this. And I'd really appreciate any ideas that you guys have.

Just one more thing, I live in Australia, and white leds cost aus$8 each, which is about us$4. And there's no where to get them cheaper. Plus I asked the shop, they dunno where/what brand they are, so probably made in china or taiwan. If there's anyone from Melbourne here and know of places to buy leds cheaper, please let me know.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by yclo:

warning, about 1mb of photos
<HR></BLOCKQUOTE>

Your server seems to have a good connection (unlike the CPF server) as they were here in a few seconds....

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
So, to my main point. I'm interested in converting this to an led light.
1. How many leds am I gonna use? (And how long will they last?)
2. Will I need a step-up circuit?
3. Should I use the original reflector?
<HR></BLOCKQUOTE>

If you use one of these Ledcorp bulbs you will have the simplest modification, just changing the bulb.

If you want to do it by yourself you will need a stepup circuit. You may try the Versalux module

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
4. If I have a lot of leds, then maybe I can have white leds surrounding, say 3 blue ones. Then I can add a little switch to change to just 3 blue (for longer use) or lotsa white ones for brightness. Or should I bother?
<HR></BLOCKQUOTE>

You may easily combine blue and white LEDs.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> If you use one of these Ledcorp bulbs you will have the simplest modification, just changing the bulb. <HR></BLOCKQUOTE>

Would it be ok to use in the plastic housing? It's a bit expensive though..
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by yclo:
Would it be ok to use in the plastic housing? It's a bit expensive though..<HR></BLOCKQUOTE>

Yes, you are right. You will have to maintain some heatsinking.
And you get what you pay for. Most people here buy the LEDs from whiteleds but you may ask Gadget about his group buy
 
The idea of using leds for bicycle headlights is usually considered "moot" by most riders, because leds are nowhere near as bright, bulb-for-bulb. The drop-in led Pelu is recommending is the new Lumileds item I believe, which is a great item, but even then you have little more light than what's in your Cateye now. To get a significant usable light output from a solid-state light will take a lot more money, batteries, and also a bigger "donor" light than what you have here. If you just want a bright bike light, why not search out some of the free designs on the Web based on MR11 bulbs. These can give really strong illumination, often for less than $50 if you do it yourself...
 
You won't gain battery life if you build a LED as bright as a halogen. LED have similar efficacy as halogen bulb. LED lights gain battery life only by giving out less light.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> Yeah, it's true I'll get a brighter light if I use a halogen lamp, but battery life is not very long... <HR></BLOCKQUOTE>
This is the area that still confuses me. Unless the new Luxeon Star (or other LEDs) have become significantly more efficient, a halogen actually makes better use of energy. Traditionally a halogen is more efficient than an LED. So, at equal brightness, a halogen lamp will use less electricity than an LED lamp. I love LEDs, but I've never seen definitive proof on this forum that LEDs can outperform halogen when you need a bright light. Someone, please prove me wrong so I can justify a new high power LED flashlight! (Of course I am aware of their long life and ruggedness)
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by RonM:
Traditionally a halogen is more efficient than an LED. So, at equal brightness, a halogen lamp will use less electricity than an LED lamp.<HR></BLOCKQUOTE>

Perhaps this is true, but usually LED lights have a boost converter, so that way the battery is "good to the last drop." While I suppose that this is possible using a halogen bulb, I have never seen one using a regulator. So, while a halogen may be as efficient, the LED is still running while the halogen would be yellow and fading.

Why don't they use boost regulators with ordinary bulbs???
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> Why don't they use boost regulators with ordinary bulbs??? <HR></BLOCKQUOTE>
My guess would be that incadescent lights aren't as voltage sensitive as LEDs. Of course their output drops with voltage, but they probably provide light over a wider voltage range. It also seems like LEDs can't be designed for a specific voltage. Otherwise we'd see white LEDs made for two battery flashlights. It's probably easy and cheap to design an incadescent for almost any battery voltage. Step-up and step-down circuits also create inefficiency. So why gum up a simple device like an incadescent flashlight with circuitry if you don't need to. That's my guess.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Harrkev:
Perhaps this is true, but usually LED lights have a boost converter, so that way the battery is "good to the last drop."
<HR></BLOCKQUOTE>

Actually the vast majority of LED lights just use 3 alkaline cells (of different sizes) and a couple of LEDs.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
While I suppose that this is possible using a halogen bulb, I have never seen one using a regulator.<HR></BLOCKQUOTE>

A halogen bulb needs a regulator even more than a LED. Read Willie Hunt's page.
 
So leds are taking over incandescent for low power lighting, such as hand held torchs.

But halogen's are still winning the battle?
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by yclo:
So leds are taking over incandescent for low power lighting, such as hand held torchs.

But halogen's are still winning the battle?<HR></BLOCKQUOTE>

Again and again:
It depends what you want to have. You tell who you want to win and I tell you how to manage it.

A good halogen bulb with 5W (and we all agree that the SureFire assemblies are good ones) brings about 12lm/W out of the lens with ~100 hours filament lifetime. You may overdrive it a little and getting 15lm/W at a lower lifetime.
But this is only true when you drive it at it's perfect working point, which is never accomplished unlike you use, for example, a Willie Hunt LVR.

If you use a Nichia white LED and drive it with no more than 2-3mA a piece, you may easily get more than 20lm/W, when driving them at nominal 20mA you will get 15lm/W (good heatsinking provided). If you take selected ones, even somewhat better. Lifetime will be 10,000 hours.
When you overdrive them (as most lamp manufacturers do) efficiency goes down. At 100mA you will get 6 lm/W at 200 hours life.

Luxeon Lumileds are at some 9 lm/W at nominal current (their datasheets are not very accurate).

So when you can afford hundreds of LEDs and do not need a real spotlight, you can get better efficiency.
 
Just a note -

the "converter circuitry" (actually various dc/dc converters used by LED lights) can be applied to halogen lamps as well - I recently put together a video light where a constant color temperature (and 100W output) were desired, even though the battery voltage was draining during the operation of the lamp - the solution was a constant voltage supply (a dc/dc converter) which was 90% efficient - it also drained the batteries dead while still giving white light instead of that yellow-orange light you get as the batts die. As a side benefit, it had an output to indicate the charge status of the batteries (with leds) so you could judge how much time was remaining on the lamp.

I looked at LEDs, even the future of LEDs, and when you need ALOT of light, unfortunately, LEDs are not as efficient as some of the high pressure filament bulbs, which are not as efficient as the discharge bulbs (metal halide, etc) - a MH lamp assy would do nicely, but the added cost and complexity of a driver for it offsets the gains today in using that lamp - batteries are cheaper than MH drivers!

There is supposed to be a 10W MH assembly (complete with driver and reflector and bulb) comming soon that will run on 7, 9 or 12 VDC - but with a price tag over $100, it's likely to find very few buyers.

(as a side note - in my video light application, the ability to select the voltage the dc/dc converts dished out was a real asset, since it directly determined the color temperature of the light, and made for a constant color exposure - for photographic work, this is critical, whereas for flashlight work, it's not nearly as much of an issue)
 
I did a simple conversion of a similar light...
The pictures show my simple resistor voltage dropper. I still havent gotten around to making up a true voltage converter. However, even with this inefficient setup, I still get approximately 15 hours of light on low and about 8 on high... It dims so slowly that one cant tell...

-Daniel
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by hmmwv:
There is supposed to be a 10W MH assembly (complete with driver and reflector and bulb) comming soon that will run on 7, 9 or 12 VDC <HR></BLOCKQUOTE>

Actually there are ballasts available for 8, 10 and 11 alkaline/NiXX cells.
 
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