General Lighting with LEDs

AC? No, they would flash at best, but you must observe the maximum current requirements for each LED.

The best LEDs for normal lighting are going to be white. You could blend red, green, and blue to get different colors and temperatures.

White light is not white light. There are different temperatures for light. Most interior lights are a soft-white, about 3,000 Kelvins. Daylight is 6,000 Kelvins and looks harsh inside your home.

Reflectors and lenses help put the light where you want it. Standard LEDs tend to have a forward cone of projection, but the angle of that cone varies among the different LEDs.

High output LEDs for lighting usually require a heat sink. Heat will shorten the life of LEDs.

The LED bulbs you buy at the store have an internal power supply to drive the LEDs.

Thank you for taking the time to answer my question. My approach is to use wall plug-in battery eliminators to power an array of LED's. I'm looking at using small LED flashlights that sell for around 99¢ each and operate off 4.5 V. They contain 9 LED's and are quite bright, although the beam is rather narrow, about 30°. Incandescent lamps are being phased out and the prospect of having to spend hundreds of dollars for LED lights or even CFL's, will create problems for many people. I'm pretty sure a DIY lighting project is going to be a topic of much interest in the coming future.

I had a project at work to add light in a restricted place. I chose to use LED flash light parts.I found out the hard way, flash light LEDs are not meant to be used on for a more than 10 to 15 minutes. They get exceedingly hot, and will burn out very quickly. As a bench test, I turned a flash light on and left it on my work bench. After 15 minutes, it was almost too hot to touch.

There are 120 vac LED's you can buy that should work, however.

Ronseto, Much thanks for the great topic and its' massive response. I just started playing round with entry level solar power generation. After getting the system to run a few simple AC items [lights, TV], I think the next step up is to perhaps link this little solar unit to LED lighting. I will use the info in this thread when I get to application of LED's. I am process engineer. I'm getting to learn a bit of basics in electricity, solar, etc. The cheapest solar power generation system I can find with the 4 basic units costs around 850 850 [about $100 US] - cheap parts from China. The battery is 12 Volt, DC. For the typical LED's, in-house, what would a typical current be? And do I run the LED's off the 12 volt battery or do I need transformers? What protective devices can I put in for the LED's?

regards Derek

I must subscribe to this thread as one of my projects is to investigate Hi-Bay LED lights for our shop. From my initial research, they are more expensive to buy but have a quick ROI do to much lower electrical usage and not having to change a bulb often. 1000 w Metal Halide bulbs are not cheap.

I tried high bay LEDs in a compressor building we built last year, overall they were very dissapointing ended up adding a couple of MV fittings just to get enough light. However the LED "fluoros" installed under the floor were brilliant and have saved considerable time and expense in maintenance over the standard fluoro. Highly recommend them but unless it's a small area or you want to install a whole roof of high bay LEDs I would be very wary.

JPool, I want to be careful to not sound too commercial here, but I want to share our experience with LED high bays and Wall Packs. You can get junk imported from the many AliBaba-type connections on the web.

Years ago, I went to China and made some connections at the factories. We needed a special light for a special tour. We got the light and we also got some great connections with good component companies. As a result, we import parts from several places, and build up the fixtures we need.

We have 120 watt LED high bays that replace 1000 watt Merc Vapors.

We have 70 watt high bays that replace 400 watt Halides and HPS fixtures

We have 30 watt LED wall packs that replace 150 watt HPS packs.

All have CRI of 70 or higher.

We import the parts (case, UL power supply, heat sinks, LED circuit boards, and reflectors) and assemble them for out the door at less than $200 each. We are proof testing a new design by cycling on-off every three seconds. We have one in a 155 degree hot box with its heat sink trapped in the hot space to simulate an attic space while the reflector and LED are outside the box allowing room air to enter. It's been running for 3100 hours and is still at 92 percent of initial brightness. Another is rated IP56. It seems to be fine so far.

So, the industry perception that LED is more expensive is only true if you have six layers of middle-man markup.

When we refit an arena last year the ROI was 3 years. If you have access issues (lifts needed, scaffolding, outside contractors) then of course the ROI will shorten. Our next project will probably be a church that has an undersized service entrance for the entire physical plant. When we change the down lights in the sanctuary and all the can lights in the hallways to LED, they will be able to build their new building addition without installing an upgrade to the service entrance. The ROI on that project is negative.

This is happening more an more as we find situations where we can pull out 200x250watt incandescents and replace with 100x90 watt LED and give the customer more light and more control than before.

Remember to factor in your BTU heat load savings on airconditioning.

txmedic3338, You seem knowledgable about LED lightning so I am wondering if you have any tips concerning full spectrum LED lighting to grow vegetables in the greenhouse I plan to build. I plan to have 2- 3 by 16 foot grow beds raising a variety of vegetables. Can you build a lighting system to adequately provide light over these grow beds? If not can you provide a source of someone who can?

Best bet is to use Fluor T-8 Daylight dual lamp 8 footers with reflectors and suspend them as high as you can directly over the rows, if you get the type than can dim you can set them up on automatic timers/controllers to mimic the sun moving across the sky.

First, I think this might take on off another full discussion, but I strongly disagree with the term "full spectrum" LED. There is no such device in existence, and until some chemical physics change, there won't be. Second, all the experiments I've done so far indicate that LED is too costly and inefficient (yes, inefficient) to compete with fluorescent grow lamps. Discharge lamps are even better, having far more UV energy than either LED or fluoro. I have another bit to post about this as soon as I can. I am not anti-LED at all, I am just against using the wrong tool for the job. Improvisation and experimentation are fun but expensive, and I am reluctant to encourage anyone to dive in head first to the LED pool, when the waters are still so shallow.

I have to say I´m a bit dissapointed with LEDS: they are supposed to outlive other types of lamps by far.... but the LEDS one can buy are mainly cheap generic stuff and quality is as low as their price. Where I live, bulbs / lenses on traffic lights have been replaced by round disks with about 40 to 50 LEDS per color. Less than two years later, a 10 to 15% of the LEDS don´t work any longer

like averything, you get what you pay for. And with the initial price high, its easy for the cheap imitation inferior product to make inroads on this.

how do you distinguish a good LED from cheap stuff?

yeah, the only thing you can tell on a LED is that the long wire is the + pole...

I had purchase an LED work light from Harbor freight.....it was unbelievably cheap ...... I should have bought a bic lighter instead.

Automotive LED's have a higher spec than common LED's, you could use those or just check the specifications of several makers, osram etcetera

While shoddy equipment must be an consideration, are you certain that vandalism isn't also a possibility? Besides being shot at, Earnest T may be throwing rocks at them as well.

I replaces some of the lighting in our kitchen 2 weeks ago with LED.

We have about (8) in ceiling lighting that was condolences, I replace the one with LED 60 WATT they were about $40.00 ea, not cheap but the price is coming down. The rest I replaced with lighting that was burned out in the halls. Anyways any more I'm replacing with 40 Watt. The light is so white and makes the existing condolences bulbs look pale yellow and dull.

No heat, I love them. They are a little bigger though.

Got some good info here...

http://www.energysmartindustry.com/

The typical White LED is actually a blue LED chip with a glop of yellow phosphor over it, so that the resulting light is a combination of blue + yellow = white. The color temperature is controlled by the mix and the amount of the yellow phosphor. Compared to an incandescent lamp these LEDs have way too much blue emission and not enough deep red emission, so colors can look funky under LED lighting. (It's called the Color Rendering Index.)

There are also Blue + Green + Red tri-color white LEDs, but they are trickier to energize properly and the color tends to drift as they get warm. Some LCD TVs with LED backlights use the B+G+R types to get a wider range of produceable colors. They include a feedback loop for temperature compensation.

The biggest difficulty in driving LEDs is proper heat sinking. A typical LED runs at about 3 VDC at anywhere from 0.02 to 0.3 milliamps, the brighter ones being the ones sucking the most amps. At 3VDC and 0.3 milliamps, one of those little chips uses nearly a watt of power and can have a junction temperature close to 80 C (175 F or so). That's a lot of heat in a small area. Some LEDs have a separate, neutral copper spot on the back just for heat sinking, some use the cathode lead as the heatsink. In either case, improper soldering can damage the chip. The closer the junction gets to 80 C or greater, the shorter its life will be.

interesting,

wasn't it difficult for them to actually come up with a white LED, and white LED is quite a recent thing say 10 years????, and when it was discovered it made headlines.

Yeah, the breakthrough was the blue LED, using gallium nitride, GaN.

The next big breakthrough will be a highly efficient device that mimics the black-body radiation spectrum through the visible light range. Support your local engineering school.

A typical LED runs at about 3 VDC at anywhere from 0.02 to 0.3 milliamps

Pretty sure you mean .02 to .3 AMPS, not mA

I know what you meant, just want to be sure others do, too.

Tom D.

D@mn decimal points! Yes, you are right. Good catch.

I hate picky people with nothing better to do than point out typos, but since this is math, which isn't supposed to be able to lie (unless politicians use it, I mean), milliamps is probably inappropriate here. Shouldn't this be Amps, if its .3?

"3VDC and 0.3 milliamps, one of those little chips uses nearly a watt of power"

I have a LED Flashlight that uses 5 watts.....has a focusable beam of about 300 meters. Cost around $10. Nothing unusual today about it....

I have a Coleman LED and a pocket MAGlite.

love it, turns black into daylight.

I wonder what the LED "limits" are today if you really put out some big cash?

Limts as in what?..... luminus, life.

I like to think that there will be advances in new material that will replace existing, that liminus output will increase will driving costs down. But that like any product.

I was intentionally not specific as both of the points you made are only parts of the whole story.

For example, looking at some modern cars white front lights, there are some pretty powerful LED lights around, far more than my 5 watt Cree chip......

I was hoping that someone with up to date information would reply......

I used a pair of (similar to) these @17W each to replace 2 x 250W halogen lights for a submersible robot. Dimming was required to keep the light to an acceptable level, instead of the struggling to see with the halogens. Big heatsink tied to the alu casing kept heat down.

Submersible robot, heat sink? Why? Wasn't the pond/pool/lake/river (shoot, even the bathtub) a big enough heat sink?

Never mind. I know. Waterproofing. Joking, too!

These LEDs need good heatsinking behind the LED in any environment - I used the casing to keep the heatsink cool (drinking water at 3-6C) - at ambient, a fan-driven airflow would be best.

POOL mentioned 1000Watts metal halide bulb. No, LEDs are not in this league. A car's headlight is in the range of 35Welectric. I have yet to see a low / high beam LED.

On the other hand, they are good in strings for distributed ambient light, like the picture with the stairs show. That light is strong enough to see where you are going. A workplace might require 10-50 times more light.

Hi/Lo singles have been around for a while:

http://betterautomotivelighting.com/2012/05/01/exciting-led-headlight-technology-jw-speaker-brand/1-led-housing/

The off-road world is moving right along with this technology...eager to improve lighting. Conserving power at low RPM's can be critical.

The new Rubicon can be ordered with these direct from Chrysler.

For expertise in wavelengths and lighting at high intensities, you might want to talk to cannabis growers.

"...get some of the Christmas Net Covers for bushes. String one of those matrices up against your ceiling and see if you like the quality and quantity of light."

That's what I was going to suggest but I thought I would get shamed!

I use christmas lights for my attic space and it works great without having to run new wiring and still being able to see all of my crap up there.

A set of nice full-wave lights makes great accent lighting and will last a looong time and save electricity to boot.

Thank you for the treatise on LED's and your offer of your lecture series. I didn't realize all the design and research that goes into LED lighting. I wanted to try it simply as a DIY experiment, but I can see there's more to it than meets the eye. The Christmas LED light strings is more in keeping with an amateur tinkerer like me.I can dream up all kinds of applications for LED's, but lack the knowledge to put it into practice. At 78, it's a bit too late to start.

Somebody my wife knows just finished her PhD at age 98, and a sky diver instructor friend of mine took his great grandfather for a tandem dive also age 98. 78 is too old? As compared to what? Hell, Ron, you're stll a kid!

Thanks europium,I needed to hear that. I'm really a 77 year old in a 78 body.

"AC variations will kill the LEDs very quickly, and any spikes in voltage or forward current will dramatically shorten the life." -- should we say in a Flash!

i'm not so shure how they coupe with revese voltages .. ? i've only 2 datasheets that list such

1. LUW80043-H _/¯ V_R^MAX 6V
2. HLMP-331x to -351x Series _/¯ V_R^MIN 5V

... and some about how fast'ey could be switched

txmedic3338 wrote: "You can see why Phillips and others are choosing to put the phosphor on the bulb surface, and freeing up the ability to put in a larger blue LED photon pump. Get one of those and break open the shell. Pretty blue light inside. This construction also allows a lot more phosphor coating, which does help to extend the life of the lamp's CRI index, but at the cost of efficiency in Lumens/Watt."

Exactly. Philips intro'd the precursor to their award-winning L-series LED bulb a few months before. When I spotted them for the first time on store shelves I noticed the yellow 'lens' and reckoned that inside were blue LEDs. I had to buy several and take them apart ('nerd appeal' having nothing to do with it ).

To wit:

I believe the LEDs are still evolving and the smaller wattages ones you get in the market at cheap rates are highly inefficient. The main issue with LEDs is that they have a concentrated heat flux and therefore need a proper in-built thermal management system which is being side-stepped and overlooked by majority of manufacturers in their hurry to encash the demand which is in fashion. An improperly designed LED system will fail within no time and my worry is that it will lead to some negative propaganda for this highly meaningful lighting technology.

Thermal issues become more critical when you jump to +60W applications and also with 'Chip-On-Board' (COB) LED modules. The challenge is to quickly take away the heat flux so that junction temp is maintained <80°C which will lead to durability and longer performance of LEDs with minimum illumination drop.

Good luck.

Hi Ronseto.

Can LED's operate off of straight AC?

No. They could only flash on the positive half of the ac waveform, giving a very low lighting level (and probably with a kind of flicker, not sure about that though). At least, they need a rectifier and capacitor circuit. In fact, they need more complicated circuits which supply them with constant current (instead of constant voltage) in order to be more efficient.

What combinations of LEDs can be used; series, parallel?

You can use all combinations (series, parallel and any combinations of both). Of course, for any of these implementations, you should always take into consideration the leds' operating current for their proper operation.

Would AC variations of voltage effect LED operation?

As I said, you'll get very low brightness (and, probably, flickering).

Do they require reflectors/lenses to operate efficiently? (bare bulb)

No, they do not require reflectors or lenses, unless you want to concentrate the light in a small area (i.e. spot). However, even in this case, the 'led spots' don't need any reflectors or lenses, because their light is already concetrated enough. In fact, in general lighting applications, this 'light concentration' of the leds is not desirable. So, in order to overcome this 'problem', the led-bulbs' manufacturers usually arrange many leds (led array) in the bulb properly (i.e. the leds are located in different directions), so that to get a uniform and spherical transmission of light.

Thank you for your direct to the point answer to my question.

A 1000-watt LED stadium-light module.

Amazing how far LED lighting has come. In 1985 I paid $60 for my first blue LED, a SiC affair from Siemens (I believe CREE had developed one earlier, but this was the first I'd heard). Not the saturated actinic blue developed by Nichia Chemical Industries, Ltd. some years later, but rather a pastel, almost powder blue, thanks to the broad emission spectrum. Intro'd 14 years after I'd seen my first LED. A red one made by Monsanto. Their green LEDs came out a year later. Very dim and more a 'firefly' yellow-green.

Hi Ronseto,

lots of great answers, but your knowledge simply does not run to using LEDs in the way you wish/imagine. Leave them alone and only buy quality units already designed for the house mains.

Also, for someone with such limited knowledge, you stand in danger of killing yourself (and loved ones/pets) as well......So its simply not worth it.

Some "Wallwarts" are dreadfully inefficient and any possible savings will be used up by them, with the further possibility of starting fires due to bad Chinese designs......

Leave well alone.......

Oh...boohoo...like some one couldn't hack a string of Christmas lights and not kill themselves... Live a little, man

Sadly, you also demonstrate with your post a singular lack of knowledge on the subject such as our OP does....Which of course is why I posted what I did......

A question, did you know that if the circuit breaks at any point, that the full mains voltage appears on at least one of the ends of the break on a string of LEDs/lights attached to the mains directly? One LED/light burning out for any reason will cause just that!!!

Many do not know and/or even understand this possible danger......you are obviously one of them otherwise you would not have written:-

Oh...boohoo...like some one couldn't hack a string of Christmas lights and not kill themselves... Live a little, man

Live and let die being your motto perhaps?

But certainly not mine, I always warn when there is possible danger and let the "recipient" decide for himself! You are not the OP/Recipient.

There is always at least one Nincompoop person that pooh poohs that!!! If that is how he gets his rocks off, so be it!!!!

You give the impression that you probably laugh when someone gets a shock or worse?

If true, shame on you.

Perhaps you could explain further your take on the subject?

Sadly I have had more than my fair share of shocks over the years, AC ones are decidedly "UNFUNNY", none were intentional. DC ones are usually unimportant as long as there is no extra metal present to warm things up......

I even once accidentally tripped a RCB, painful, even though only for a few milliseconds, and that was at around the current needed to light a LED......something that nobody has mentioned, but a RCB brings a vast increase in safety for anyone experimenting....

Most old houses in Europe STILL DO NOT HAVE ONE FITTED as the code law does not require it......I cannot speak about the USA, the same maybe?

Germany still does not require them even for new build houses......sad for what is thought to be a highly technical country.....also their sockets and plugs are as bad as most other European countries and the US as well, as you have to buy extra pieces to install in an attempt to make them a bit safer for when small children are around, whereas the UK's sockets are already safer, small children or not.....

Only the UK (and current & old Dominions and affiliated countries) have to my mind a relatively safe house electrical system (nothing is perfect!), BS 7671: 2008, 17th Edition (currently) since approximately just after the end Second World War with RCBs being required in new builds for around the last 40 years or so if my memory serves me well.....perhaps a UK resident could update that for us all as to exactly when the current 13 amp system started and RCBs had to be installed?

Certainly there is nothing better around today, although I haven't quite given up hope.....

Do have a safe and "not" a shocking day!

Sadly, you have received too many shocks over the course of your life. Therefore your opinion on anything electrical is suspect at best. Your own admissions of failure over the years gives one to conclude that you should not be regarded as an authority due to "experience".

I regard electricity from the same judiciuos viewpoint as I do gun safety. A gun safety instructor who has shot themselves at least one time is no longer a gun safety instructor.

Posts by and discussions with Ronseto in the past have indicated that he is neither a fool nor an "experienced gun instructor".

Further, those shocks and accidents which you admit to may have affected your choice of words in verbal discourse in an unforunate manner which also leaves your opinion to be questionable...again, at best.

Please accept my kind regards for your family and clientele.

--The Nincompoop

Want to hear a funny but true story about experts? ......... well I'm going to tell you anyways.

When I was a freshman in High School (9th grade), one of my classes was Industrial Arts. This was broken into (3) categories.

· Woodworking

· Auto Mechanicals and Metal Working

· and Graphic Arts (Drafting, Photography and silkscreening)

A few years prior and being raised on a farm and that also operated a sawmill, we would do logging in the winter months. We came accross an American Elm, must have been at least 3 feet in diameter, Dutch Elm Disease was just getting to it but it was pretty solid. I was about 12 years old at that time, It sat as a log for about a year, and when I got into High School we could choose our projects to do. I wanted to cut this Elm Log at a diagonal to make a coffee table out of it, and seal it with a (2) part polyurethane, This stuff was expensive but it gave a wet look to the wood. So my brother cut it for me, It was about 3 feet by 4 to 4 1/2 feet and I took it to school.

Well back to woodworking, My instructor thought it was a good idea, he had a lot of experience in wood. And there were some issues about it but he let me go ahead.

Anyways, he was a stickler for safety, and always had everyone copy the safety rules on tools out of a book that you were going to use. I thought this was ridicules, because kids just copied the rules but they never understood them more less actually read them.

Well, I was operated the powered hand planer and surfacing the block of Elm. and the instructor came up to me, and ask, "Steve do you have your safety rules written"

I responded "No!" He then grab the powered hand planer out from my hand and was giving me a verbal lashing, and waving the hand planer at me saying how dangerous this tool was.

Well, when he finished, he lowered the hand planer, and must have squeezed the trigger and got his shop coat he was wearing wound up in it.

I never laugh so hard, his son which was one of my best friends was in the same class with me.........He could not believe that I would laugh at that situation and he started laughing because he knew what kind of trouble I was going to be in, because of it.

Well, the instructor unraveled his now tattered shop coat from the hand planer assigned me to maintaining all the shop equipment for the rest of the school year on top of doing my project ^{(but only after I copied and wrote up all the safety rules).}

Dear Nincompoop,

I guess its pointless to try tell you anything serious about electricity, you simply search for nonsensical reasons to not understand or learn. Not my funeral.

So you may remain completely uninformed as far as I am concerned....

If you gave as much energy to learning about electricity properly, as you use to protest and search to find possible fault (imagined), we would not have as many serious accidents with both electricity and guns........nor would there be so many gun nuts as there are, especially in the USA.

At least I have not heard of any "Electricity nuts", till now anyway!!!

Just about everything you said was 100% inaccurate...... Quite an achievement!!!!

To be safe with guns, you have to both fully understand how they work as well as how they are handled. But there are still accidents!!!! Its the same with electricity.

You appear to me to be an accident seeking a place to happen with either one or the other.

At least you will probably get to die with your boots on...... if a little early maybe!!!

I wish you an accident free day......luck will hopefully help!!! Your knowledge demonstrated here certainly won't....

Hey, you're the one who admitted to getting shocked over the years, not me.

If one has a safe work ethic then one would not get shocked. I guess that's why some people refer to it as having good safety practices.

You appear to be an accident who found a home.

....and you are perfect?

Never made a mistake?

All the gun nuts I have ever met have accidentally let a shot lose when they did not intend to. Most got away with it......at least accidentally giving myself a shock, only works to my own personal detriment......nobody else was in any way inconvenienced or injured.

Only an honest person tells the whole truth, even if it works against him.....if I was in any way dishonest, I would have kept quiet, don't you agree? As most do.....

Remember, the last perfect man was crucified over 2000 years ago......

Okay, Okay...I admit...I have been shocked before...you got me there

I don't make a habit of it...it's been a number of years, like seven.

_{You really got me with that last sentence...}

D'oh...not you too!

If the safety standards for air travel were to never travel by air and live underground...what would my odds of being involved in an air disaster be?

...

That was the problem the last time I ever received a shock...damp floor and ineffective earthing...well...except through me...

It was only about 5kV, but low current...makes one reeeeeally think each time the possibility arises.

Better, until someone goes for the world's record on shallowest dive. :)

As TXMEDIC hinted at, I had already tried. I took a Christmas tree LED light string, drilled out the holes on a peg board, and pushed them through. My intent was to replace fluorescent lights in my kitchen. It seemed like it would work well, but I never took it farther than that. I felt I should probably go to an enclosed housing to insure against fire and do something to disperse the light better. It became a matter of economics and time, and I gave up on it. LED Christmas lights seem like they last long enough to make them a cheap source for the LEDs if you want to take this idea farther.

Sometime you want to say - of course no, other times; why would I answer; so! Google, Google, Google!

Go to Radio Shack and buy a basic electronic kit, and then then the answer will be apparent!

He is asking is it possible to use small LEDs on AC, if you put a series of DC LEDs connected to AC, could you make it work. He is not asking about an AC light bulb with the electronics build in. He is not asking about a rectifier, circuit built in, he wants to us AC as the supply to power DC LEDS. And not possible without other circuits before the LEDs.

Good source of tech info on leds

For a 40 to 70 % led brightness of a 5 watts 220 v ac led lamps ..... Ive been using 30 led lamps in parallel using joule ringer circuit ( laserhacker.com) from 100 to 160 mA setting using one 10 watts solar panels

Compared to candles which can lead to fire disaster...and emergency as power outage and typhoons... this seems to work ...

So it actually depends on how much brightness or application you will use it

thanks

totoalas

Ooooooh! Just found and trying out some 1.4W LED replacements for 35W and 50W GU20 240VAC filament spotlamp bulbs. Totally brilliant!