Student seeking some basic LED help for a design project.....

[tommyortom]

I am a Industrial/Product design student and I am working on a family of low voltage lighting products. I am doing a flashlight, lamp and ceiling light. The flashlight and lamp will be LED powered and I would like it to be ran off of small batteries like AA's? Also, It will be rechargeable off of a household 120v or a 12v outlet in a car. I am looking for probably 2-3 hours of runtime for each product. As far as the ceiling light, it will run off of 120v household only, since it isn't mobile. But I'm wondering if there are LEDs out there that are bright enough for a ceiling light to be effective, yet still operate on low voltage?

Here are a few sketches of what my lights will look like if this helps. I am imaging I will need at least 20 LEDs for the flashlight and the lamp. I am looking for a good website to buy the LEDs from as well.

This is the flashlight.....It is a basic triangle shape with a flexible handle/hook. The bottom and the 2 front sides will light up via LEDs. There will actually be three of these that will all dock together for storage and to charge.
http://i22.tinypic.com/2qdrjix.jpg
http://i24.tinypic.com/2l80f4.jpg

This is the lamp......it is a three sided pyramid that provides lighting on all sides, but the sides will fold out to provide a more focused output of light. i am looking to include the same LEDs and power source as the flashlight.
http://i20.tinypic.com/6916b7.jpg
http://i20.tinypic.com/fok7sh.jpg

This is the ceilling light.....this uses three retractable lights to provide a spread out light output, and they will retract in to provide a more focused light output. This product will probably need brighter LEDs since it will be mounted on a ceiling and must shine down farther.
http://i24.tinypic.com/34dt0uv.jpg
http://i20.tinypic.com/vfwc2p.jpg

 

[tommyortom]

One more thing.....I took some LEDs from this display at my work that are pre-wired onto small individual circuit boards and these run off of 4 AA batteries for a while, and are pretty bright. Once I decide what LEDs to use, I'm wondering if they can be bought on these little circuit boards? It makes installing them real easy, just drill a hole and glue them in!

http://i24.tinypic.com/25qxlaq.jpg

 

[tommyortom]

I am a Industrial/Product design student and I am working on a family of low voltage lighting products. I am doing a flashlight, lamp and ceiling light. The flashlight and lamp will be LED powered and I would like it to be ran off of small batteries like AA's? Also, It will be rechargeable off of a household 120v or a 12v outlet in a car. I am looking for probably 2-3 hours of runtime for each product. As far as the ceiling light, it will run off of 120v household only, since it isn't mobile. But I'm wondering if there are LEDs out there that are bright enough for a ceiling light to be effective, yet still operate on low voltage?

Here are a few sketches of what my lights will look like if this helps. I am imaging I will need at least 20 LEDs for the flashlight and the lamp. I am looking for a good website to buy the LEDs from as well.

This is the flashlight.....It is a basic triangle shape with a flexible handle/hook. The bottom and the 2 front sides will light up via LEDs. There will actually be three of these that will all dock together for storage and to charge.
http://i22.tinypic.com/2qdrjix.jpg
http://i24.tinypic.com/2l80f4.jpg

This is the lamp......it is a three sided pyramid that provides lighting on all sides, but the sides will fold out to provide a more focused output of light. i am looking to include the same LEDs and power source as the flashlight.
http://i20.tinypic.com/6916b7.jpg
http://i20.tinypic.com/fok7sh.jpg

This is the ceilling light.....this uses three retractable lights to provide a spread out light output, and they will retract in to provide a more focused light output. This product will probably need brighter LEDs since it will be mounted on a ceiling and must shine down farther.
http://i24.tinypic.com/34dt0uv.jpg
http://i20.tinypic.com/vfwc2p.jpg

 

[Derek Dean]

Howdy tommyortom, and welcome to CPF,
My first stop would be over at the 'Homemade and Modified lights' area of CPF:

http://candlepowerforums.com/vb/forumdisplay.php?f=17

My second stop would be the 'Flashlight electronics, batteries included' area:

http://candlepowerforums.com/vb/forumdisplay.php?f=9

There are 'Threads of interest' at the top of each area with lots of information to get you going. Good luck with the project, and I'll look forward to seeing what you come up with as a final product. We love new lights!

BTW.... you might want to consider resizing your photo, it comes out a bit large to really see well.

 

[LukeA]

12V is enough to run 4 modern high-flux LEDs (SSC, Cree Q-bin, Rebel100) at about 350mA in series, which would give you somewhere in the neighborhood of 400 lumens at around 4.2W of draw off the battery. A setup like that would give you about three hours of runtime off of a 1Ah lead-acid battery, or 8 hours off of 8AAs.

For the ceiling light, a series of 4 LEDs at 350mA in each triangle will get you about 1600 lumens, or about the equivalent of a 100W incandescent bulb with a total draw of 17W, or 12V @ 1.4A. You will need resistors to limit the current to each string so that one string doesn't hog all the current and possibly get into thermal runaway.

Also, you could easily run these LEDs at higher currents (up to ~1A each), but efficiency suffers and heatsinking becomes a serious concern.

 

[LukeA]

All high flux LEDs are available on stars, which are basically this same concept, premounted emitters with easier soldering contacts, except that the stars are made of aluminum and are meant to help in heatsinking. They are ready to be mounted basically anywhere.

Please don't double post.

 

[serious sam]

you might want to consider resizing your photo, it comes out a bit large to really see well.

+1

 

[Lyndon]

Hi tommy:
Those are amazing drawings. Wish I could do that stuff

Like LukeA said, you can get high wattage LEDs mounted on hexagonal "stars" but they will still need leads soldered to them and proper power supplies, not to mention proper heat sinking. Power supplies can be purchased easily, or DIY is not hard.
Can you solder? Smaller LEDs like the ones in your photo (T 1-3/4) are not available already mounted to circuit boards in single units, but if you have soldering skills, it's pretty easy to buy a few of the tiny boards from Radio Shack and solder LEDs to them. Or depending on how you want to mount them, you can purchase panel mount sockets for T 1-3/4 LEDs.

One of the "concepts" I'm working on offering at my website is rapid prototyping supplies for LEDs so basic lighting systems can be designed easily without much electronic skills. But the site's not ready for prime time yet. You can take a look at www.cedarlakeinstruments.com/products & www.cedarlakeinstruments.com/products/led.html if you'd like to see what I'm working on (ignore the HDPE stuff: I just put that up there quickly so someone could order that specific item).

Since questions like yours are just the kind of thing I want the site to answer, I would really welcome your feedback

-l

 

[tommyortom]

Hi tommy:
Those are amazing drawings. Wish I could do that stuff

Like LukeA said, you can get high wattage LEDs mounted on hexagonal "stars" but they will still need leads soldered to them and proper power supplies, not to mention proper heat sinking. Power supplies can be purchased easily, or DIY is not hard.
Can you solder? Smaller LEDs like the ones in your photo (T 1-3/4) are not available already mounted to circuit boards in single units, but if you have soldering skills, it's pretty easy to buy a few of the tiny boards from Radio Shack and solder LEDs to them. Or depending on how you want to mount them, you can purchase panel mount sockets for T 1-3/4 LEDs.

One of the "concepts" I'm working on offering at my website is rapid prototyping supplies for LEDs so basic lighting systems can be designed easily without much electronic skills. But the site's not ready for prime time yet. You can take a look at www.cedarlakeinstruments.com/products & www.cedarlakeinstruments.com/products/led.html if you'd like to see what I'm working on (ignore the HDPE stuff: I just put that up there quickly so someone could order that specific item).

Since questions like yours are just the kind of thing I want the site to answer, I would really welcome your feedback

-l

I can solder and have a good understanding of electrical stuff to be able to put together whatever parts i order without a problem....i just need to know what a good choice is for a model to build. im actually only building the flashlight with the handle and am looking for some leds to put in it, as well as a small battery source. the bottom of the light and the 2 sides will light up, so im planning on having the bottom of the light which has the most surface area product the most light, whlie the sides will probably be less? i just need to see what an LED setup would be....hopefully this thing is bright, and gives off a spread out pattern of light. but that might not work depending on the lense i use over the leds for my model?

 

[tommyortom]

All high flux LEDs are available on stars, which are basically this same concept, premounted emitters with easier soldering contacts, except that the stars are made of aluminum and are meant to help in heatsinking. They are ready to be mounted basically anywhere.

Please don't double post.

i can solder fine so i should be able to make these work into my model. do you have a link to these pre mounted leds?

 

[tommyortom]

12V is enough to run 4 modern high-flux LEDs (SSC, Cree Q-bin, Rebel100) at about 350mA in series, which would give you somewhere in the neighborhood of 400 lumens at around 4.2W of draw off the battery. A setup like that would give you about three hours of runtime off of a 1Ah lead-acid battery, or 8 hours off of 8AAs.

For the ceiling light, a series of 4 LEDs at 350mA in each triangle will get you about 1600 lumens, or about the equivalent of a 100W incandescent bulb with a total draw of 17W, or 12V @ 1.4A. You will need resistors to limit the current to each string so that one string doesn't hog all the current and possibly get into thermal runaway.

Also, you could easily run these LEDs at higher currents (up to ~1A each), but efficiency suffers and heatsinking becomes a serious concern.

i did a quick search for those leds you listed and their all flashlights....i was hoping to just buy some LEDs in bulb and make them work into my model design that i have to build, which is the flashlight with the handle.

 

[B@rt]

Please read the rules regaring double and crossposting as well as picture size.

 

[frenzee]

For your ceiling light, you can achieve the equivalent of a typical 100W incandescent bulb (roughly 1500 lumens) with 10-20 high-power LEDs, e.g. Luxeon K2s, Luxeon Rebels or Cree XR-Es, depending on how hard you want to drive them, but the harder you drive an LED, the less efficient it becomes and the more heat dissipation issues you have to deal with. As a rule of thumb, for power LEDS, 350mA is a safe level to start with.

You can purchase the Luxeons and some drivers directly from Philips Lumiled's website, and as for Crees and other driver circuits, look in the Buy/Sell/Trade and Group Buys sub-forums. If I may suggest, try to stick with warm white or neutral white tints for indoor applications since they are closer to natural lighting and much easier on the eyes compared to "cool white" tints.

BTW, I really like your designs. Also, AFAIK, the forum rules regarding image size only discuss images "in your post". The way I read this, it refers to images embedded in your post, which if large, could slow down loading of the page and interfere with page formatting. Images hosted elsewhere and linked to here are, technically speaking, not in your post.

 

[tommyortom]

Please read the rules regaring double and crossposting as well as picture size.

sorry about that. im not on my personal computer and cant resize the images right now, but i see that someone linked them, thank you. the images were too large...i agree. i will resize and rehost them later on.


just wondering....would buying a batch of white LEDS like the ones on ebay and just using as many of them as i need be a bad idea? how many of these could i run for 2-3 hours off of a small battery source?


http://cgi.ebay.com/50-PCs-UltraBri...yZ105796QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/New-Product-100...ryZ66952QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/ebaymotors/20X-...015QQitemZ250168433836QQrdZ1QQsspagenameZWDVW
http://cgi.ebay.com/NEW-30X-5mm-BRI...yZ105796QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[LukeA]

just wondering....would buying a batch of white LEDS like the ones on ebay and just using as many of them as i need be a bad idea? how many of these could i run for 2-3 hours off of a small battery source?

You could, but it would be more difficult and the result would probably not be as good as with a few high flux LEDs.

SSC stars
Cree Q2 stars

 

[Melchior]

5mm Array

I think for a prototype an array of 5mm LEDs may actually be a good choice.

If it only has to work for short periods, than buy a pile of cheap wholesale Chinese LEDs.
Cut out several PCB boards and get soldering. All you would need extra would be resistors, a battery holder and some wires / switch.
With a 4AA battery back, 20 run of the mill 5mm white LEDs would last about 2 hours.

However for that Triangular "Flashlight" I would use a Production setup like this:

21 x 5mm (T 1-3/4) White 40,000mcd Nichia LEDs

2 x CREE XR-E P4 Series 1 Watt Power LEDs

Each small side of the "Triangle" has 7 Nichias in a line.

The two Large faces each have a CREE XR-E on a heatsink.

I'd use 4 Li-Ion Cylindrical 18650 cells for power and a constant current regulator chip.

Would give a bit more than 1 and a half hours. With PWM dimming it could go MUCH longer.

However; Myself I don't think this design lends itself to the strengths of LEDs... a CCFL tube would be much better for the sides.

 

[tommyortom]

Re: 5mm Array

I think for a prototype an array of 5mm LEDs may actually be a good choice.

If it only has to work for short periods, than buy a pile of cheap wholesale Chinese LEDs.
Cut out several PCB boards and get soldering. All you would need extra would be resistors, a battery holder and some wires / switch.
With a 4AA battery back, 20 run of the mill 5mm white LEDs would last about 2 hours.

However for that Triangular "Flashlight" I would use a Production setup like this:

21 x 5mm (T 1-3/4) White 40,000mcd Nichia LEDs

2 x CREE XR-E P4 Series 1 Watt Power LEDs

Each small side of the "Triangle" has 7 Nichias in a line.

The two Large faces each have a CREE XR-E on a heatsink.

I'd use 4 Li-Ion Cylindrical 18650 cells for power and a constant current regulator chip.

Would give a bit more than 1 and a half hours. With PWM dimming it could go MUCH longer.

However; Myself I don't think this design lends itself to the strengths of LEDs... a CCFL tube would be much better for the sides.

yeah, this is just a model for my project, it doesnt have to light up exactly how i would envision it looking as a real production product. I'm trying to not spend too much money on the LEDs...maybe 30-40 bucks at the most for the LEDs alone? I will probably have 100 bucks and a lot of time into the model though once it is finished.

oh...and the top of the flashlight doesnt light up where hte handle is....that would just shine up in your face while your carrying it hahaha. just the bottom side and the 2 smaller sides pointing forward will light up.

 

[tommyortom]

You could, but it would be more difficult and the result would probably not be as good as with a few high flux LEDs.

SSC stars
Cree Q2 stars

those both look like they may work well for my model, they are pretty cheap, shallow and seem easy to install into my model.....

how bright is one of those? i may be using 2-3 on the sides and 4-5 on the bottom maybe?

lets say i use 10-12 of those in my model....what type of small batteries like a 4 AA setup would these be able to run off of and for how long?

 

[tommyortom]

my model itself will mainly be built out of 20lb modeling foam and/or some polystyrene that i will have to vacuum form into whatever shape i need and im not sure what im goin to do about the rubber/flexible handle.

 

[Melchior]

lets say i use 10-12 of those in my model....what type of small batteries like a 4 AA setup would these be able to run off of and for how long?

Are you talking about the CREE or Seoul SSC Star emmitters??

AFAIK nobody has used more than 6-7 CREE based lights, and even then with crazy giant heat-sinks and runtimes measured in minutes.

If you have not actually seen a Power LED in operation, and know their electrical and thermal properties, then I really would not recommend their use for anything with a plastic/foam body. It would MELT. Each 1 Watt LED, emits alot of light and alot of HEAT as well.

Of course here on the CPF sanity can often take a hike... as it were.

So without further ADO your potential shopping list:

EMITTERS:

CREE XRE P4 (older but still quite powerful):
http://www.dealextreme.com/details.dx/sku.1302

Power supply:

A 'Buck-Puck' -- may need several
http://www.ledsupply.com/02009a.php

Or This -- drives the LEDs hard, but more in line with what you want:
https://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=2982

Heatsink:

Basically you need a big chunk of Aluminum or copper to stick those LEDs onto. Bigger is better, go for overkill. Use thermal paste.

Batteries holders and wires / switches -- local stuff (try auto parts shops)

I would use this simple rule:

1 NiMH 2500 mAh battery for EACH CREE emitter used, with a appropriate drive circuit.