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LED lighting, no longer a novelty

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  • LED lighting, no longer a novelty

    I have been experimenting with LED lighting for some time now. Up until recently most LED lighting has been more decorative than truly functional. That's about to change. It will only be a short time and you will begin to see LED "light bulbs" that are very satisfactory replacements for incandescent and CFL bulbs.

    I recently purchased 3 ultra bright 5 watt emitters to test as a replacement for a small flood light at our back door. This has always been an issue since we like to leave it on but don't want to waste a lot of energy. We would commonly have a 100 watt incandescent and that can add up fast if it is on nearly 24/7 in the winter. CFL bulbs just won't operate at the low temperatures we experience at that time of year.

    So, I modified a small cast aluminum floodlight housing that I bought for about $5 some years ago. It was intended to use a 300 watt halogen which was out of the question for this application. I removed the innards and the 117 ac wiring and made a small plate of 1/4" aluminum to fit in the base of the housing as a heat sink on which to mount the diodes.

    This is what the emitters look like,

    The heat sink includes a small sheet of copper clamped to the back side of the aluminum mounting plate. That copper is bent around to conform to the housing side wall and fastened to it to allow the housing to act as a radiator for the waste heat of the diodes.

    This is what the flood light looks like with the diodes operating:

    The diodes are glued to the mounting plate with heat sink glue compound. This makes mounting much easier than using mechanical fasteners.

    The power supply is a 1.5 amp 5 volt unregulated wall-wart power supply. It is a perfect match for the three diodes which are wired in parallel. No current limiting was required as the power supply is exactly matched to the load. Each diode draws about .5 amp but can be operated as high as 1 amp at reduced lifetime.

    This is a 1 second exposure of the illumination this light provides. This exposure is subjectively very close to how it appears to the eye, power consumption about 15 watts. The emitters cost $4.90 each.

    Last edited by Evan; 05-23-2009, 06:04 AM.
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  • #2
    Good info! How well would that work for a machine tool lamp? Do these LED's emit a tight beam or a wide flood? I'm needing more illumination for my lathe and mill. Halogens are too hot, and normal LED's aren't quite bright enough to suit me.



    • #3
      Very interesting.

      Is this what you were using?

      Where you able to find a better price than $27?


      • #4

        I picked up something similar as a replacement "bulb" for my 2D MagLight. Holy smokes is it bright, and the batteries last a LOT longer.



        • #5
          $4.90 each from Dealextreme. ( in quantity of three)

          It's bright enough that a lamp with about 9 emitters like that would illuminate a small shop decently. I intend to build a few more such lamps because they will run a long time from a UPS.

          The emitters are unfocused and provide about a 90 degree beam of light with perfectly even coverage. The color is between warm and cool white, very natural looking.
          Last edited by Evan; 05-23-2009, 08:45 AM.
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          • #6
            LED lights are also starting to show up in theater/concert settings. My side job is working for a small audio porduction co. and we've talked about getting some of the new led cans for our setup. 1000 w light output w/ far lower current draw. That's a big plus for our situation. Last summer we did an outdoor show, threw the breaker on a 135 kw genset- and we weren't running everything as far as the lights went, just finally pulled enough juice to trip the breaker. (IIRC, the audio end needs about 60 kw for all the amps- this doesn't include the stuff that a band brings with them)

            Our lighting guy thinks that we could get 48 lights, our standard outdoor rig, and run them on something like 1\3 the power. Plus, no more color gells, supposedly the leds can do all the colors. It's surprising how much light output is lost when the gells are in place.


            • #7
              The biggest issue when working with LEDs like this is to provide adequate heat sinking. While they don't produce a great deal of waste heat that heat is concentrated in a very small area. The power density with an emitter like this is unreal. The active area of the 5 watt emitter is only a few square millimetres. That puts the power density up in the range of 100 watts per sq centimetre so proper heat sinking is mandatory.
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              • #8
                Of course many of the traffic liights in the U.S. have now been converted to LED arrays. They give a much better light at greatly decreased current usage.

                I have some of the small ones on my model railroad to show turnout position and for signals that have been running for many years. If the current is limited properly they really don't burn out in normal use.

                I think the OP's LED lights would be grrat for a shop. I'm tired of buying 8 foot fouorescents every now and then. I will have to look into them.

                Last edited by gnm109; 05-23-2009, 05:44 PM.


                • #9
                  Evan, what has changed to make these a viable primary lighting source?


                  • #10
                    A lot of things are changing very quickly. The main thing is cost. Last year an emitter like this was $20 each. Now it is $5 and by next years they will be down to a buck or two at most. Also, new processes are coming online right now that make it possible to obtain very much better efficiencies. That is absolutely necessary because of the high power density. You can only remove so much heat from a small area without resorting to active methods and that isn't a viable solution for lighting in most cases.

                    There are units now that can compete directly with incandescent in terms of brightness and have much lower consumption. There are also direct drop in replacements for fluorescent tubes but they are still expensive.

                    Go to and search on Cree. Cree is a brand name USA manufacturer of LED emitters headquartered in North Carolina with manufacturing in the US. That's right, you can buy a US made product from Hong Kong cheaper than you can buy it in the USA.

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                    • #11
                      There are some very interesting LED form factors shown here:


                      But no prices.


                      • #12
                        The project is really interesting.

                        You talked about Deal Extreme in the past. I have been hesitant to order. As you know, the total 'true cost' of importing from the US via UPS has has soured me on the process. USPS is OK.

                        For the benefit of the Canadian guys, what might we expect in charges when purchasing from DE.

                        Thanks in advance.


                        • #13
                          I'm convinced that within the next 5 years, LED technology will render both incandescent and fluorescent lighting obsolete.

                          I have a couple of workspaces where I do close work (jewelry) that require cool, even lighting. I'm thinking about trying one of these:

                          I recently read of another new development, something having to do with a layer of "quantum dots" over the LED that provides a "warmer" incandescent-like color without sacrificing efficiency.


                          • #14
                            Dealextreme often has free shipping, and they routinely mark the package as "gift" and then quote a lower value than reality. This avoids some, but not all, customs hassles.

                            I've used LED lights on my small lathe (7x12) and micro mill for several years. They perform pretty well. I have older leds that are only 1 watt and about 30 lumens. Modern replacemnts will be 5 times as bright using the same power.

                            How much is 30 lumens? It uses a reflector, and at 10 inches from the LED it reads the same on my light meter as a 250 wattt halogen 4 feet above my work bench.

                            If you decide to make one, keep in mind that there is a big difference between the low power LEDs found in the real cheap flash lights and the high power LEDs such as Luxeon, Cree and Seoul. A low power LED is used in lights such as the ones with 22 leds running on 3 aaa batteries. You get 1 to 5 lumens per LED.

                            Traffic lights use low power LEDs, but they use a lot of them and the light is focused towards the driver.

                            I highly recommend LEDs.

                            At the end of the project, there is a profound difference between spare parts and extra parts.

                            Location: SF East Bay.


                            • #15
                              I bought an LED floodlight at Costco the other week. Not super bright, and rather blue, so I'm using it in the ceiling mounted can in our pantry; it's plenty bright for that and the instant on is perfect. The kids sometimes leave the pantry open, so I didn't want to go back to halogen, and CFL just take too long to turn on.

                              I think I need to experiment w/ some of these 5W parts...

                              - Bart
                              Bart Smaalders