Author Topic: LED's for task lighting? (Read 7667 times)

Mike in Utah · « **on:** January 27, 2006, 07:12:58 PM »

Hi there,

I just signed up for this forum and may place this question in the wrong area. Please forgive me if that is the case.

I want to make a task light for my lathe using super bright LED's. I can design the circuit okay but don't know what LED's to use. Can someone suggest a part number?

Thanks in advance...

Mike

willib · « **Reply #1 on:** January 27, 2006, 02:10:08 PM »

Luxeon(tm) are the brightest available today , i believe..

http://www.luxeon.com/

ghurd · « **Reply #2 on:** January 27, 2006, 02:34:08 PM »

Other companies are making similar LEDs now.

They are bright, but not efficient. A 'regular' bulb can do better.

LEDs last longer if that's important.

The 5mm LEDs are more efficient, cheaper per lumen, and will last longer than the high power LEDs.

I'd suggest a 40 degree 5mm.

Don't push them too hard, maybe 15ma. Heat kills.

If efficiency is the goal, use twice as many LEDs at half the amps each. It will be brighter with the same power.

Measure the amps. Generic internet LED math is usually wrong by a long way, overpowering the LEDs, meaning a much shorter life, and not as efficient.

Start at 3.2Vf calculated circuit design for modern white 5mm LEDs.

If it's too good (cheap) to be true... It's junk.

G-

Mike in Utah · « **Reply #3 on:** January 27, 2006, 02:52:33 PM »

Thanks for the responses so far!

I notice that super bright LED's have a rating from lets say 500 mcd to 18000 mcd. Should I buy the highest rated mcd ones to get my desired "brightness"? I'm confused because the 500 mcd one cost only a few cents less than the 18000 mcd ones.

Thanks...

ghurd · « **Reply #4 on:** January 27, 2006, 03:27:40 PM »

You need to know the viewing angle too. AKA- 'two theta one half'. 20 degrees is standard.

Thats how it is focused.

Like a 'mag-light'. The bulb is just as bright as it is. If it is set for a tight focus it is very bright, and reaches a long way. If it set for a wide focus, it 'seems' not as bright and doesn't reach out very far.

It is making the same amount of light, just putting it in different places.

The bulb did not magically get brighter!

About 8000mcd is around standard for good LEDs at 20 degrees now. 3-4000mcd is good for 40 degrees. Premium LEDs are higher mcds, but they are hard to get.

Surplus houses often list the MCDs of premium LEDs while selling seconds, or list the 'max mcds' instead of typicial mcds. Like if the data sheets say 'min 5000mcds, typ 6000mcd, max 9000mcd', you can bet the max mcd units were sorted out (thats why they are surplus), therefore expect less than 6000mcds. They buy my rejects.

I have a knee-deep 'surplus' of genuine first quality 50 degree white LEDs right now. Chinese New Year messed me up. ghurd1 at yahoo

G-

Mike in Utah · « **Reply #5 on:** January 27, 2006, 03:50:40 PM »

Would Mouser.com be a good place to get the super bright LED's?

terry5732 · « **Reply #6 on:** January 27, 2006, 05:17:51 PM »

I'm perfectly happy with the 10,000 MCD white LEDs I bought from a Hong Kong dealer on Ebay .They take 8 -14 days to arrive from there. About 1/10 the price of Mouser. You can usually find a listing for these at about 20 for $8.00 or so. Or compare to the 500 MCD ones at Radio Shack for $6.95 EACH.

Mike in Utah · « **Reply #7 on:** January 27, 2006, 06:07:43 PM »

Okay...let me rephrase my question.

To get quality LED's do I buy by brand name or is it the supplier that needs to be the deciding factor? If it's the brand name than what is a good name? If it's the supplier, can you recommend someone?

Thanks...

Mike

wooferhound · « **Reply #8 on:** January 27, 2006, 06:32:07 PM »

Why don't you use a compact fluorescent bulb? They are brighter, more efficent and have better color.

Mike in Utah · « **Reply #9 on:** January 27, 2006, 07:23:55 PM »

Woof,

The task light I'm replacing is a halogen. The trouble with this light is that it is too hot and being on a lathe, coolant can splash on it. I'm hoping that LED's will do the job and I won't have to worry about the bulb exploding from the errant coolant.

If the LED's don't work out, I might very well take your suggestion of using a fluorescent bulb.

Thanks...

Mike

Tom in NH · « **Reply #10 on:** January 27, 2006, 08:49:58 PM »

I have a bunch of 20Kmcd and 35Kmcd white leds as well as nice circuit boards. --tom www.altenergyweb.com

Mike in Utah · « **Reply #11 on:** January 27, 2006, 09:27:55 PM »

Tom,

I went to your website. Pretty nice!

I don't know how many LED's I would need to add to get a good task light. I have a halogen light on a lathe that has a lamp holder on it that is 2.125 inches in diameter. I would remake this and add the LED's necessary. I guess I will have to experiment a bit to see what they can do.

What brand are your LED's?

Thanks...

Mike

terry5732 · « **Reply #12 on:** January 28, 2006, 12:36:26 AM »

As a side note:

Notice how many new traffic lights are now LED and how bright they are. Then look closer and you will see some are out already, when they may have only been in use for weeks or months. The sellers of these lights tout their efficiency and longevity. Then they scimp on costs and overdrive the LEDs for more light at less cost. Result is very premature failure. With this overdrive on them, as soon as about 10% burn out the rest cascade. Lights sold as long lasting often last less than a year. Then the unknowing buyers will be going back to incandescent. All because of some shysters trying to cut corners for a few extra cents per light. In this area, I noticed my first LED traffic signal less than two years ago and have seen catastrophic failures already. You only get longevity at the rated power or under. Far better to halve power and double quantity.

Mike in Utah · « **Reply #13 on:** January 28, 2006, 01:34:10 AM »

Terry,

Good point!

Mike

ghurd · « **Reply #14 on:** January 28, 2006, 07:50:10 AM »

I like Nichia products. They sell direct now and the prices have come down a lot. Not very cheap yet.

Nothing LED at Mouser impresses me, especially the 'LED replacement bulbs'. Yuck.

I don't believe most retailers know much about the LEDs they sell.

G-

Tom in NH · « **Reply #15 on:** January 28, 2006, 01:04:50 PM »

Thanks for the nice comments about the web log. The LEDs are a nameless generic Hong Kong brand. My opinion is a LED is an LED is an LED. The important thing is to use care in designing the circuit they will be in so as not to overdrive them. The high current luxeon type leds do vary in quality by brand. They are very prone to overcurrent abuse and can get amazingly hot. The plain old T1 leds don't get hot. --tom

scottsAI · « **Reply #16 on:** January 28, 2006, 01:51:01 PM »

You will thank your self later if you follow what wooferhound said.

Based on efficiency: Based on SAME light output.

If incandescent bulb is a 1

Long life incandescent bulb is 1.1

halogen is 0.9

LED is 0.7 voltage drop resistors will make it even worse, 0.8 to 0.9

CF is 0.25

CF is much cheaper than LED for 120v on par at 12v.

Quality CF runs cool, not affected by coolant.

Have fun,

Scott.

dinges · « **Reply #17 on:** January 28, 2006, 02:58:23 PM »

I'm using a CFL on my lathe; no problems yet (for about 5 years now). The odd splash of coolant doesn't seem to harm it.

What Woofer said holds. LEDs are nice for SMALL task lighting. But when it's efficiency you want, go for CFL.

As far as the Luxeon/Lumileds go: anyone ever had a look at the cooling flange & cooling fin they need? IMHO, if it needs something big too cool it, it can't be too efficient...

Peter.

ghurd · « **Reply #18 on:** January 28, 2006, 04:14:41 PM »

For task lighting, LEDs are good if you want to run them from DC. Not really a great choice for 120/240AC. Not a great choice for a LOT of light either.

Did you see this...

http://www.fieldlines.com/story/2005/12/17/33433/804

G-

hobot · « **Reply #19 on:** January 28, 2006, 04:26:08 PM »

Interesting and educational disscussions as usual.

I have one comment to consider beyond the energy/life time factors.

For some reason I've found that LED's as a task light for

tight fine details gives a fuzzy disfuse light without good contrast.

I much prefer even a weak indcandescent or flourescent lamp.

Better barrow a LED flash light and see if it satisfies your vision.

hobot

Aaron · « **Reply #20 on:** January 28, 2006, 08:02:14 PM »

http://www.superbrightleds.com

these guys have a lot of choices

aaron

wooferhound · « **Reply #21 on:** January 28, 2006, 08:11:59 PM »

If you make an LED light, this page will help out a lot with the electronics.

http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm

Mike in Utah · « **Reply #22 on:** January 28, 2006, 08:43:08 PM »

Thanks again guys for the help!

I'm kinda stuck with the type of light to use. The head of the lamp is a cylinder approx 2.125 inches in diameter and 3.00 inches in length. If I try and use CF's the bulbs are just too large. I can always go back to halogen, but I was hoping to try something different.

My thought was to try and use LED's as they seem interesting. I'm going to start with a 12 volt DC circuit. Since I'm haven't any experience with LED's I was hoping to get some advice from you all as what type to use and about how many.

I saw the link to superbright.com. Have any of you had any dealings with them?

Again, thanks for all the help!

Mike

ghurd · « **Reply #23 on:** January 28, 2006, 10:05:11 PM »

The dimentions are not important.

Imagination and the reflection/2ThetaHalf is all that count.

willib · « **Reply #24 on:** January 29, 2006, 10:02:28 AM »

holy crap Ghurd ,someone is really into LEDs..

are those yours?

hydrosun · « **Reply #25 on:** January 29, 2006, 05:32:58 PM »

I've gotten leds from superbrightleds.com The individual leds have been great. Some of the multiple leds have had multples of three quit. I think they use one resistor to limit all the parralel strings instead of one resister for each string of three. I was using the leds in headlights with 12 volt nickle metal hydride battery packs. I think the initial high voltage of a freshly charged pack may have overloaded them. I still use them even if the light is dimmer with 15 leds instead of 21. I have a 30 led unit with an older nicad battery that I've never had a problem with. So if these units are used on a controlled 12 volt supply they seem to last a long time.

Chris

ghurd · « **Reply #26 on:** January 29, 2006, 06:26:29 PM »

Yep. Made in an off-grid shop too!

Mike in Utah · « **Reply #27 on:** January 29, 2006, 06:35:32 PM »

hydrosun,

If you don't mind...What was the part number of the LED's that you got from superbrightleds.com?

Thanks

willib · « **Reply #28 on:** January 29, 2006, 06:40:43 PM »

Is that one in the center bottom for 12V ? a car taillight/ brake light?

and those that screw into to 120V sockets are neat,how did you drop the voltage to a useable level for the LEDs , and what how many watts do they use?

ghurd · « **Reply #29 on:** January 29, 2006, 07:33:23 PM »

Bottom center is a reworked #1156 tail light bulb.

The '120V sockets' are actually fed 12V. It lets the bulbs be used in any standard lamp. Desk lamps, swing arm lamps, table lamps...

Some use 6V spring tops, depends on what the user wants. The tiny LED bulb is probably a 4.5V for a camping lantern. We even make them to run with cordless tool batteries.

These, including resistors, use between 0.05 and 1.75W, but we make another bulb that uses 0.024W for a nightlight!

RobD · « **Reply #30 on:** January 29, 2006, 09:44:19 PM »

I've done lots of work with LEDs and high efficiency supplies. I like LEDs and the Luxeons and Crees are getting better efficiency every improvement but they have there limits.

For one thing LEDs don't have great forward projection unless you use the high power ones and the power supply efficiencies lower the overall efficiency.

The best bet is, as Woof said, CFLs and I've used them on my lathes for years. The color is better and the light is better.

If you want then get the 12v volt CFLs for off grid but even with a small inverter they work well using the 120 AC bulbs. A $29.95 inverveter at 400 watts will drive a string of them.

I've bought the nine year life bulbs at Home Depot and gotten six bulbs for around 10 bucks. That's hard to beat and the LEDs can't touch that price. Just make sure you get the ones that say fit for enclosed places, they have higher heat ratings.

RobD

zyewdall · « **Reply #31 on:** January 30, 2006, 12:09:18 PM »

LEDsupply.com has good ones. I'd go for the Luxeon 1 watt or 5 watt LED's. The Elara and Io Moon ones also seem to be good -- they use the nichia LED's. They are much brighter per watt and cheaper than trying to cobble something together out of even the brightest 5mm LED's. They also have the drivers you'll need to run them (you can also just use a dropping resistor, but you get better control, and higher lumens per watt if you you use the current regulating driver).

There is also a 7 watt Luxeon -- I haven't seen it for sale commercially yet, but the US military uses it with some optics for a tactical weapon (blinds people temporarily).

I don't think a CFL would be real happy on a lathe -- too much vibration. LED's are much better with that.

Zeke

zyewdall · « **Reply #32 on:** January 30, 2006, 12:13:46 PM »

One additional thing. Make sure you heat sink the 1/2 watt and above LED's. They'll burn out pretty fast if you don't.

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Author Topic: LED's for task lighting? (Read 7667 times)