LED noob here with a simple question - 76 LED head light

I have started looking into a head light for a bike (a trike recumbent w/electric assist actually). So naturally I went looking into LEDs, off to ebay, lots of stuff from china.

I am curious, is something like this just as waste of money?

http://cgi.ebay.ca/76-LED-Bicycle-Torch-Head-Flash-Light-Bike-Lamp_W0QQitemZ150302461210QQcmdZViewItem?hash=item150302461210&_trkparms=72%3A1215|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14

As I read more about Luxeon, Cree, etc I realize that more leds must not equal better/more light.

*And it also looks like it would be fun to build my own headlight

UPDATE: hyperloop asked for some photos, so here they are:

Just read your post, could you post a pic of your trike?? Havent seen one of those before. And, a picture of your trike may assist in recommendations for lights and mounting systems as not everyone (speaking for myself) has seen a trike.

And yes, more LEDs doesnt mean brighter and better.

You might want to check out this thread in another part of CPF

http://www.candlepowerforums.com/vb/forumdisplay.php?f=86

Thanks for the quick reply.

Well the trike is a homemade job, and we are currently working on a fully enclosed body (for the wet cold days we have here). The head light will be nested into the nose of the body.

I am now looking at building something with a BuckPuck 1000mA and 3 Luxeon III's or the K2 (but of course now I read that the newer Cree's are better).

The 'master' plan is to have headlight, front/rear signals and a tail/breaklight all running off a 12V battery.

As for pictures, I don't have any new ones of the body yet, but I will soon (I hope to have it on the road by the end of the month)

I know I have some pics of the trike itself around here, I will post one when I find it.

And thanks for the link to the Bicycle sub forum.

maybe these pics can give a slight help:

lights:


that "showerhead" light:


Showerhead to the rear tyre, + the L1D:
(for Your application: an underdriven Cree)


all getting kicked by a Cree @ upper spec current (~ 850-900 mA):


Your 70+ Led showerhead might be brighter than this multihead here, but only good for a space of 3 meters and lost against a single powerled.
With 20 mA per Led, it should run on ~ 1,5 A, which equals to almost full power of two Cree/Seouls.

For your purposes, 3 cree's running off a 350ma buckpuck should be enough, or go to the 700ma version which will be easily enough to light your way, especially at street level, and probably too much to use full power without dazzling other road users. I certainly don't recommend white luxeons (though the red-orange ones are pretty good for rear lights), and IMO driving an LED beyond 700ma gives very little additional light, and uses a lot more power and makes a lot more heat. Alternatively you could get the dimmable buckpucks, wire up a couple of resistors and a switch so it runs at 150ma/700ma for low/high. This will give you over 100 lumens on low, and about 500 on high (with cree R2's... halve these values for luxeon III's)

FYI ryancr, there's a bicycle-lighting section under "Transportation Lighting" where you might get more cycling-specific answers and ideas.

Those showerhead lights aren't that good compared to high power ones.

Don't use Luxeon IIIs, they are last gen LEDs. That means half or less the output at the same power compared to current gen LEDs.

You probably don't even have to assemble a whole new light. An easier way might be to get two of these drop-ins for the headlight. Make sure they get the right heatsinking and place a piece of glass, plastic, whatever to prevent the reflector from direct impact.

:welcome:

Thank you all for the great replies.

I can see how one could really get into this LED thing. Some pretty cool stuff out there, and I am sure I have only scratched the surface.

Gunner12 said:

Those showerhead lights aren't that good compared to high power ones.

Don't use Luxeon IIIs, they are last gen LEDs. That means half or less the output at the same power compared to current gen LEDs.

You probably don't even have to assemble a whole new light. An easier way might be to get two of these drop-ins for the headlight. Make sure they get the right heatsinking and place a piece of glass, plastic, whatever to prevent the reflector from direct impact.

Click to expand...

These drop-ins look great, just have to build a housing to hold 3 of them. If I do use these I think I will have a switch that has 1 on for low and 3 on for high. Seem reasonable?

Oh and thanks for the link to dealextreme, looks like a fun site.

Gunner12 said:

:welcome:

Click to expand...

Thanks!

Maybe you guys can give me a couple of ideas for the rear of the bike body.

So I am in the process of create a fully enclosed body for my recumbent. This is what the rear of it looks like:



What I would like to do is have a strip of yellow/amber on the left and right side for turn signals and a strip of red in the middle for tail/brake light.

Would something like this be bright enough:
http://www.dealextreme.com/details.dx/sku.5211

or these:
http://www.dealextreme.com/details.dx/sku.11304
(Its to bad this one doesn't have a yellow/amber)
(I wonder if I could mix some of the green and red to make an orange)

For the blinking I was just going to rob the innards of a standard bike blinker but since I want to run 12v I don't think that is possible. So I assume I have to find/build a blinking circuit.

The other thing I need to figure out is if a run a red strip for the tail light, can I "over-volt?" it to increase the brightness for when the brake is on?

I guess I could just run a second strip that only comes on when the brake is on, so It would be twice as bright.

ryancr said:

Would something like this be bright enough:
http://www.dealextreme.com/details.dx/sku.5211

or these:
http://www.dealextreme.com/details.dx/sku.11304
(Its to bad this one doesn't have a yellow/amber)
(I wonder if I could mix some of the green and red to make an orange)

Click to expand...

If you're using it for a bike, I advise something a bit more reliable. Orange lux 3's or K2's wouldn't be a bad idea for this application. The DX strips may fail on you, which would be bad! Also, something I saw and think is a good idea is to have the indicators form an arrow. So the left indicator points left (rather like < ), rather than just lighting up on the left.

As for mixing colours, no way. The drivers will just see green and red and be like "What?", not to mention the horridness of finding multiple circuits to run the LED's.

ryancr said:

For the blinking I was just going to rob the innards of a standard bike blinker but since I want to run 12v I don't think that is possible. So I assume I have to find/build a blinking circuit.

Click to expand...

Correct. I very much doubt those circuits will take 12V

ryancr said:

The other thing I need to figure out is if a run a red strip for the tail light, can I "over-volt?" it to increase the brightness for when the brake is on?

I guess I could just run a second strip that only comes on when the brake is on, so It would be twice as bright.

Click to expand...

In a word, no. You might be able to increase the power slightly, but red doesn't handle high power very well. I advise the second strip method.

You can probably also use two switches, one for turning on one module and the other one for turning on the other two modules. Make sure that the modules get some heatsinking though or they might over heat(you might not need that much since moving air will help a lot with cooling.

The LED strip seem pretty simple, but it is always possible to have bad solder joints.

You can probably build something similar with separate LEDs or a single high power LED in a translucent tube.

You would probably have to find a blinking circuit.

As for the break lights, you can drive the LEDs and 1/3 or half current for normal and full current for braking.

Gunner12 said:

You can probably also use two switches, one for turning on one module and the other one for turning on the other two modules. Make sure that the modules get some heatsinking though or they might over heat(you might not need that much since moving air will help a lot with cooling.

Click to expand...

This is what I am thinking for the head light from deal extreme:
Qty 1
Desc 3*Cree Reflector - Orange Peel Aluminium (18mm x 50mm)
SKU 11921

Qty 3
Desc Cree XR-E R2 (WG) Emitter on Premium Star
SKU 15943

Qty 3
Desc MR16 1*3W 320~350mA Constant Current Regulated LED Driver (12~16V Input)
SKU 13557

Sound reasonable?

The only thing I am not sure of is the Driver, if I would be better to get a single buckpuck instead w/ Dimming Control

Gunner12 said:

The LED strip seem pretty simple, but it is always possible to have bad solder joints.

You can probably build something similar with separate LEDs or a single high power LED in a translucent tube.

Click to expand...

Yeah I am thinking high power LED now, the translucent tubes gives me some other ideas too, thanks.

Gunner12 said:

You would probably have to find a blinking circuit.

Click to expand...

I think I will just make one using a 555 timer chip, I am still going to look for a premade one, but the 555 setup doesn't look to hard to build.

Gunner12 said:

As for the break lights, you can drive the LEDs and 1/3 or half current for normal and full current for braking.

Click to expand...

That makes good sense.

The simplest thing to do might be to buy 3 of the prebuilt drop-ins and use them, but then you have less control on the exact output. You'd have 3 levels, 1 module on, 2 module on, or all three modules on.

I don't know much about the driver for the headlight if you want to build from parts because I haven't made one myself. The Biking section and Homemade/Modified section might have the info you need.

Just a quick update, I like to thank everyone for there help with my LED questions. I have everything 'on the way'.

See the very first post for pictures of what they are going on.