Some joints beg to be silverbrazed

You'd win that bet, Ted. Microscope ringlight first, though.

I seem to do more projects for others than I do for myself, but I do get around to my own projects eventually.

Last I looked ( a couple months ago) some LEDs were showing efficiencies approaching flourescents and better than any incandescent.

An array of five such would provide 600 lumens, would be much more compact than a flourescent and could easily provide a desireable emmision pattern.

Ted

Thanks for that, Ted. I see that the 'Luxeon V portable' LXHL-LW6C is rated at 24.8 lumens per watt. This is a nice improvement over quartz halogen which is a measly 20 lumens per watt.

Neither compare favorably with: Fluorescent (Halophosphate) 60 lumens per watt Three band (Fluorescent?) 90 lumens per watt Low pressure sodium discharge 200 lumens per watt

Here is one technical challenge to the Luxeon.. We would have to lose over 24 watts of heat through five electrically - isolated heatsinks capable of holding heatrise down to say 10 degrees C per watt. Note that this is not optional because Lumileds stops warranting device life if the device exceeds 15 degrees per watt per device (allowing for the thermal resistance of a Silpad between the device and sink).

The contact area of each sink is a circle measuring about 16 mm in diameter Those aluminum rod sinks would have to be about 40 cm long in order to provide the 10 degree C / Watt performance without liquid cooling or forced convection (and allowing for convection from sink to sink).

Perhaps we could trick the eye with PWM control of current to limit the amount of waste heat. Dunno.

Maybe someone makes a 50W low pressure sodium discharge lamp with a dichroic reflector. That would be nifty.

--Winston

500 lumens would be a 40-watt MR-16 halogen bulb. Four 5-watt Luxeons (20 watts) would produce 480 lumens with half the heat.

I found a 25-watt MR-16 to be plenty bright for a mill light. This would be about 312 lumens.

Further, given brightness level (illuminance) in a small task region can be much higher per lumen with Luxeons because they can produce a much smaller and more evenly-illlumnated spot than an MR-16 can. If the region of interest is 3" dia but the MR-16 produces a 6" dia "spot", illuminance from a 3-watt luxeon producing 80 lumens with a

3" dia "spot" would be very neearly the same as that produced by the 25-watt MR-16, about 17,000 lux. My region of interest on a mill is the immediate vicinity of the cutter.

I therefore think that a single 3-watt Luxeon directed right at the work site (as in a mill lamp) would provide ample illumination. The head would be very small and unobstrusive -- about 1" dia and 1" long including collimator. If the body were aluminum, it would have about 3.14 sq in of surface, more if it had little fins. That would probably be enough heatsink for a 3-watt Luxeon. It would be warm but not nearly as hot as the 25-watt halogen.

Life-cycle cost would actually be lower, because the 3-watt Luxeon has a life of > 50,000 hours. That's quite a few compact fluorescents, and even more halogen bulbs. First cost for the Luxeon and collimator would probably be about $25.

You really wouldn't want to use LPS as a microscope lamp. LPS has one gigantic spike of energy in the red-orange area of the visible spectrum, and that's about it - the Color Rendition Index is bubkis.

Probably why they were never very popular in actual use unless the accountants were driving the purchasing decisions, and even if the efficiency is lower people go to HPS where they get a little spread in the spectrum. The lone holdout in our area still using LPS parking lot lights is a community college with no budget for buying new fixtures.

Or if they can stand a little less energy efficiency they go to Metal Halide lamps to get some fairly decent color rendering, even with the cheaper everyday lamps. Big stadiums and sports venues buy the better MH lamps with the specially blended halide gases for consistent color spectra and a higher CRI rating.

-->--

I'm not familiar with "Three band". Can you give a reference or an alternate name?

I would find the colour of sodium lamps quite unpleasant in the shop.

Why would this help? I would expect the PWM drive to give about the same result as DC at the average current of the PWM drive.

Ted

I think he may be talking about "cool white."

That is a phosphor that generates blue and yellow, which is percieved by the human eye as 'kinda white.'

The halophosphate is a sodium fluorapatite IIRC that has a better color rendering.

Basically cool-white is one of the most energy efficient phosphors but it makes everyone look a bit like an undertaker did a bum job.

Jim

Low Pressure Sodium has two strong yellow lines - often thought of as one. It is almost pure yellow as the lines are doublets and very close to each other. I have a 2000mm F10 telescope and thus must filter out the wonderful LPS lamps. Easy.

The HPS - sucks. This consists of nicer for the human eye to use - blue, green, yellow and red. Sucks because a filter is very complex to make and when done, blacks out much of the sky.

Indoors LPS would give a poor color balance and create a 'black and white' field of play. Whereas HPS would give a richer color balance and create a modified color field of play.

IIRC, Cypress Microsystems makes a chip or has a programmable chip that modulates the long white tubes. It was found that frequency was the way to control them - something like PWM but FM. IIRC 20kc is the max useful value.

Martin

I wasn't playing fair.

What I am looking for is a bright, lower temperature light so that I can see my workpiece through a #9 welding lens. That is going to require significant flux density with very little regard to color.

Don would like a small, low temperature spotlight so that he can see his milling cutter more easily. (I would take one of those, too!)

You, Bruce would like a cool source of light with the same color temperature as the Sun for use on a microscope stage.

I don't think there is one type and size of illuminator that is the best answer for any two of these applications, let alone all three!

--Winston

Invented in '73. Look at this URL under the category "Non-Incandescent Lighting":

I expect that they are talking about 5000-5900 K "full spectrum" lamps. Like:

Yes, but as I mention in another post, color might not be that important. If the lamp lit up my workpiece so that I could very easily see it through my #9 welding lens, that would be very pretty, indeed.

Yup. But if we lowered the actual average current somewhat without affecting the light output 'too much' the LED heatsink would not have to be so huge. The LED spec sheet shows that you can overdrive the part somewhat, for short pulses to modulate the intensity of percieved light above and below the normal D.C. value.

I wonder how many lumens per watt for HPS and if anyone makes a miniature diachroic version in the 50 - 100 W range? Is 'Metal Halide' the same as HPS?

OK. I have two of those in our bathroom. Wanted to try comparison re colour balance.

Is this for general purpose welding? You *really* should try an auto darkening helmet! I bought a Selstrom when I got my TIG and it is truly wonderful. Adjust from 9 to 13 and is about 3 in the light state. Fast enough that if I point my camera at my face and flash it, I don't see the flash. Had to get my wife to confirm that the flash fired.

If you are conserned about power consumption of an LED lamp, a switched mode power supply using current control is the only way to go - just dial up the current you want.

Ted

I saw no spectral distribution comparisons. They must be out there, though.

Naw. I'm TIGing thin steel, requiring less than 150 amps.

I bought and tried three. The latest was a Jackson NexGen EQC.

The trigger light is so far in the noise that the helmets 'flash' on and off by themselves if adjusted to blank out the meager light produced by the low current levels at which I work. I find that very annoying.

These are all fine helmets for say, assembling large battleships.

They also said the NexGen was a good choice for low power TIG. Bah. :)

My thoughts exactly. I was more concerned about keeping the LEDs cool enough to last the entirety of their rated 1000 hours' life, without the comically huge heatsinks that implies.

Heck, right now I am using a miniature 50W quartz halogen flood lamp.

48.25 watts of that are turned instantly into heat.

Power consumption is not my top priority. :)

--Winston

Something is wrong here. My Jackson EQC autodarkens just fine at 10 amps with TIG. The sensitivity control is set about 1/3 of the way between "min" and "max". You may be "blinding" the sensor with high levels of ambient illumination. Maybe that's what you mean by "so far in the noise".

What do you consider "huge"? A heatsink 1.5 x 1.5 x .7 (Thermalloy 375024B00032) will have a rise of about 40C above ambient at 3 watts with convection cooling -- no fan.

The 5-watt Luxeons are very shortlived compared to the 3-watt units, and cost about twice as much. I think using 3-watt units is a better approach for anything beyond a flashlight intended for intermittent use.

Something is _very_ wrong here! My Selstrom has a sensitivity control which I usually have set at about 1/3 of the way up. I have TIG'd a thin (about .015" thick) stainless steel piece from my neighbour's toaster oven at about ten amps. The helmet worked perfectly. This was in my fairly well lit shop - 8 40W flourescents, white walls and ceiling. TIGing outdoors when the wind is calm requires more careful adjustment if it's sunny.

I have also done quite a bit of repair work on 2" diameter, ~0.040" wall irrigation pipe. I do this at about 50amps. Again no problems with the helmet, only weldor incompetence.

I can't comment on NexGen since I havve only used my ten year old Selstrom but I'm sure others will since it is a very popular hat.

Was that 1000 hours a typo? I've read 50,000 to 100,000 hrs estimated life which would be over five years of continuous operation. At a probable usage, I would expect the lamp to outlast me by far.

Nor mine but singed eyebrows gives a bad smell. :-)

Ted

I found a text page on Metal Halide - sounds like a cat meow!

The Metal Halide Story

Metal halide lamps are one of the fastest growing light sources in the United States today.

Metal Halide lamps have gone through a revolution of change and improvement over the last several years. New technology, particularly pulse start technology, now allows users to select among a broad variety of lamp types to suit a wide range of applications. Venture Lighting has developed many unique lamps to satisfy the needs of end users. Advancements in lamp and ballast designs along with the inherent qualities of metal halide lighting account for its phenomenal growth:

1. Versatility: Venture Lighting International has been responsible for developing numerous innovative lamp types. Today there are almost 400 styles available. These new lamps types have made it possible to use metal halide in almost any setting, including industrial, commercial, retail and residential applications.

1. Efficiency: Metal halide is a highly efficient, compact source of white light, available in a variety of different color temperatures to accommodate users' needs. In contrast, high pressure sodium and mercury lamps are very limited in the color and quality of light they produce. The colors they generate are often unpleasing or inappropriate for many applications. This helps explain why the use of metal halide lamps continues to increase dramatically each year around the world. This is best evidenced by Venture Lighting's Uni-FormÒ pulse start lamps.

2. Life: Metal halide lamps have exceptionally long rated lives of up to 30,000 hours, as seen in Venture's MS 400/BU/ER lamps.

1. Color: This light source can be manufactured to produce almost any color of light desired (2700K - 20000K) and also offers an excellent color rendering index (CRI) of 65-85. Specialty lamps of specific colors can also be produced, including; Blue Deluxe, Green Deluxe, Aqua Deluxe, and Pink Deluxe. These lamps are unique in that no filtration or gels are involved in the generation of color; instead, the metal halides in the arc tube are selected for their ability to generate individual saturated colors.

2. Ecology : Metal halide provides a partial solution to one of the most challenging problems faced by our industrialized society - the ecological impact of power generation. It is the smallest high efficiency optical package available, and the most energy efficient white light source known to man. Converting to energy efficient metal halide lighting could save an estimated 10% of the total energy consumed in the United States, resulting in a potential savings to consumers of over 16 billion dollars each year. In addition, dramatically reducing fossil fuel consumption would in turn reduce emissions of pollutants, such as carbon dioxide, sulfur dioxide and nitrogen oxides. Long lasting and compact metal halide lamps can also make a significant difference in the amount of solid waste produced each year. Metal halide lamps provide 45 times the lumen hours that incandescent lamps do so that relamping and lamp disposal need to be performed less often.

extracted in full from :

Martin

Not a typo, even a stretch. . The Luxeon 5-watt devices are short-lived, not yet ready for prime time IMHO. The 3-watt devices are far better at half the cost.

The ambient was provided by about 80 watts of fluorescent in a two-car garage. Hardly 'high levels', wouldn't you agree? Maybe mine is broken.

Let me send you the helmet and you can compare it with your EQC in your copius spare time. No rush. Waddaya say?

Yup, but the Luxeon III Star operated at 1A would require 8 parts to equal the light output of five 'Luxeon V Portable' units, with a heat load of 29 watts instead of 23.7 watts.

Here is some background on the 5 watt parts: I scribbled some figures on an envelope that indicated a need to lose 4.73 W worth of heat from *each lamp* at a temperature rise not to exceed about 12 C / Watt. Each sink attaches to one lamp that is no more than about 16mm in diameter. That would require 17.4 cm2 of sink per lamp. So a solid rod 16 mm in diameter and 35 cm long would be needed for each lamp. Clearly, one would do everything to increase the surface area of the sink to gain 'headroom' but five rods, each 16 mm in diameter and

35 cm long would be a good starting point.

It also struck me as being huge.

--Winston

'Sok. I am going to try to con Don into comparing my EQC with his. We shall see.

Yup, my mistake. Life is claimed at 500 hours, not 1000.

:)

--Winston