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  • Welding Light

    Here is something I posted on another site. An attempt to improve bead/puddle tracking. Sort of compliments the "welding helmet light" post last week.
    http://www.garagejournal.com/forum/s...d.php?t=201995

    R,
    HAP
    Who do I think you are...?

  • #2
    Thats a cool idea Im using a halogen type work light so I can see a bit better, but I really like the arm idea. Also like the fact the light doesnt set off the helmet, as I find if Im welding outside its a pain in the butt, as I have to keep using a hand to cover up the sensor until I get myself set up.

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    • #3
      Thanks Stern. The other thing I forgot to mention is there is no additional cord(s) to trip over with the arm set-up.
      Who do I think you are...?

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      • #4
        This is a very interesting post. I learned something that explains a lot that I have not been clear on. If you look at the packaging for the lamp it has two illumination ratings, Lumens and "Scotopic Lumens". Scotopic Lumens is something that I did not know about until now and it is the first time I have seen such a rating. It explains why high colour temperature LED lamps appear so much brighter for the same lumen output compared to incandescent lamps. See here for the explanation:

        http://www.lightenergysource.com/Scotopic.htm

        Basically, the higher the colour temperature (within reason), meaning the more "white" the lamp is the more it involves the rods and not just the central cones in the fovea of the eye. This increases visual acuity and has the same effect as a much brighter light source than the normal lumens rating would indicate. It explains why I find my vision is much better using "pure white' or "natural white" LED lighting at a colour temperature of 6000 to 6500 Kelvin. Incandescent lighting is only around 2500K to 3000K at best. An LED lamp at 6500K will appear about twice as bright for the same lumens rating.

        I like the idea of that lamp. I have several flat plate LED emitters that put out about 5000 lumens at 6500K. One of those mounted on the helmet and designed to turn on when the helmet is down should be just the ticket.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          what kind of heat sink would you need for one of these?

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          • #6
            I get the feeling that the custom lights with a high scotopic index are largely marketing hype.

            Originally posted by Evan View Post
            http://www.lightenergysource.com/Scotopic.htm

            Basically, the higher the colour temperature (within reason), meaning the more "white" the lamp is the more it involves the rods and not just the central cones in the fovea of the eye. This increases visual acuity and has the same effect as a much brighter light source than the normal lumens rating would indicate. It explains why I find my vision is much better using "pure white' or "natural white" LED lighting at a colour temperature of 6000 to 6500 Kelvin. Incandescent lighting is only around 2500K to 3000K at best. An LED lamp at 6500K will appear about twice as bright for the same lumens rating.
            I'm not sure how accurate my research was, but the things I read say that sight involving the rods is LESS acute due to the reduced number of nerve endings outside the center of the retina (the fovea) where the rods dominate. If the rods share nerve endings the end result is higher sensitivity at lower resolution.

            An interesting experiment that demonstrates the difference in rod VS cones; Take a paperback outside on a bright moonlit night with no other light sources. Give your eyes a chance to acclimate. Marvel at how clearly you can see everything. Then try to read the book. For more, read this; http://science1.nasa.gov/science-new...angemoonlight/

            Some people have more sensitive eyes, but not most.

            The less acute vision outside the fovea explains why you can see things in your peripheral vision, but not in any detail.


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

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            • #7
              Originally posted by dian View Post
              what kind of heat sink would you need for one of these?

              One of which? The LED or the CFL?

              The 1000 lumen LEDs are often around 5 watts. Several square inches of surface area are often enough to keep it below the meltdown point.

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

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              • #8
                I get the feeling that the custom lights with a high scotopic index are largely marketing hype.
                It's real as far as the sensitivity index of the rods vs the cones and the differing spectrum. The rods are about 3 times more sensitive to blue light than the cones are to green light according to here: http://hyperphysics.phy-astr.gsu.edu...on/bright.html

                It explains that for the same actual light output the rods perceive the intensity as maximum at 507nm equal to 1700 lumens per watt while the cones see the maximum at 555nm and only 683 lumens per watt.

                That extra blue with high colour temperature has a direct impact on the perceived brightness of the light source and what it illuminates. One result of greater apparent brightness will be that the pupils will constrict more giving sharper vision. That particularly applies to astigmatism as it is directly proportional to the lens aperture.

                The 1000 lumen LEDs are often around 5 watts. Several square inches of surface area are often enough to keep it below the meltdown point.
                Best I have seen is about 120 lumens per watt and that is usually overdriving them. 100 lumens per watt is pretty much the standard at the moment. That will go up.
                Last edited by Evan; 05-27-2013, 11:34 PM.
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  Originally posted by Evan View Post

                  That extra blue with high colour temperature has a direct impact on the perceived brightness of the light source and what it illuminates. One result of greater apparent brightness will be that the pupils will constrict more giving sharper vision. That particularly applies to astigmatism as it is directly proportional to the lens aperture.

                  The 1000 lumen LEDs are often around 5 watts. Several square inches of surface area are often enough to keep it below the meltdown point.
                  Best I have seen is about 120 lumens per watt and that is usually overdriving them. 100 lumens per watt is pretty much the standard at the moment. That will go up.
                  I was fudging the 5 watt figure. My 800 lumen light only pulls 2.8 watts from the battery. Of course I have no idea whether it is 800 lumens.

                  Part of the problem with the scotopic idea is that the extra constriction of the pupil is based on a light level lower than what is optimal for the the cones.

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

                  Comment


                  • #10
                    Not necessarily. It applies when there is plenty of light too. Our eyes are designed to work in full sunlight and not many shops have light that bright. The eye has an absolutely incredible dynamic range. The human eye can adjust over about 24 f-stops range.

                    As far as the ratings on the lamps, don't trust everything you read, especially at DX. I look up the manufacturer LED spec sheets to see what is really happening. It will also tell you when the published rating is far from realistic.
                    Last edited by Evan; 05-28-2013, 12:12 AM.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #11
                      Originally posted by Evan View Post
                      As far as the ratings on the lamps, don't trust everything you read, especially at DX. I look up the manufacturer LED spec sheets to see what is really happening. It will also tell you when the published rating is far from realistic.
                      Oh, I never believe DX. They are optomistic, to say the least. You have to take the spec sheets with a grain of salt too. The output is dependent on so many factors, including the temperature of the die. Take the Cree XML which is rated at 1000 lumens, but almost 30% less light at high temps. The maximum current is 3 amps but that creates a lot of heat. That 1000 lumens is also for the best grade of Cool white. You lose 40% if you pick the best 85-cri model.

                      It's clear to me that most people do not have a 1K lumen single LED light. We speak in terms of a 1000 lumen LED but the reality is that there are virtually none used at their full potential in consumer grade lights.

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

                      Comment


                      • #12
                        Originally posted by Evan View Post
                        Not necessarily. It applies when there is plenty of light too. Our eyes are designed to work in full sunlight and not many shops have light that bright. The eye has an absolutely incredible dynamic range. The human eye can adjust over about 24 f-stops range.

                        As far as the ratings on the lamps, don't trust everything you read, especially at DX. I look up the manufacturer LED spec sheets to see what is really happening. It will also tell you when the published rating is far from realistic.

                        Evan,

                        you are so right about the spec's. The next day after finishing my light, I decided to see what the AMWATT meter showed in terms of amps and watt usage. I was totally surprised to see a reading of 6.8 amps and 800 watts!!! So much for the "Uses only 200 watts" claim. It dose not even come close to the 400 watt equ rating.
                        I compared it to a four bulb High Bay T-5 fixture and found it to draw only 220 watts. Unless they have a totally diferent way of measuring things, thier advertized specs are wayyyy off.

                        R,
                        HAP
                        Who do I think you are...?

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                        • #13
                          Originally posted by HAP View Post
                          I decided to see what the AMWATT meter showed in terms of amps and watt usage. I was totally surprised to see a reading of 6.8 amps and 800 watts!!!
                          I'm afraid the AmWatt isn't giving you the real picture. From the instruction leaflet - "The AmWatt assumes a power factor of 1. The AmWatt cannot provide accurate readings for compact fluorescent light bulbs. CFLs have an irregular sine wave and only a TRUE RMS meter can measure them accurately."

                          In other words it's pretty near useless for anything other than heating (i.e. resistive) loads.

                          A CFL may have a power factor of around 0.5. This would imply the 800W AmWatt reading is double the true watts, however the current waveform makes even the 6.8amp measurement doubtful, so I wouldn't entirely discount the stated 200W figure.

                          On the other hand the high bay fitting is quite likely to be power factor corrected (maybe better than 0.9), so the AmWatt reading will be closer to the truth.

                          Cheers

                          .

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                          • #14
                            Power factor is certainly an issue. Our 230 vac split phase power here isn't even close to a good sine wave anymore. It has major visible distortion on my good HP oscilloscope. I wonder how much error that introduces on my old analogue power meter? I should note that our power is locally produced by an ~80 megawatt waste wood burning plant. It doesn't have the benefit of averaging over a very large load distributed over a very large area.
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                            • #15
                              Barrington, thanks for the informative feedback. I feel a little better about the light now. I was affraid that thing was worse than an equivalent Halogen... Good to know info.

                              R,
                              HAP
                              Who do I think you are...?

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