Building a short arc searclight

Thanks guys. I thought on how to make the mount for quite some time and I'm actually pleased with how it turned out. Just hope it works as good as it appears to when I actually have a bulbs mounted and all the extra weight it's gonna add. I have several different length and strength springs to fine tune it's performance if need be.

Should work fine. Another option is to focus the lamp with this setup. Measure the height of the adjusting plate on each corner. Then remove the springs and use two nuts on each rod. One over and one under the plate. Since you have the measurement, you will be very close on fist try. That will never move, and you can still adjust it. Just a little bit more inconvenient.

Good idea! That would definitely hold the bulb in the proper place as you said. Ill keep that in mind.

Made the lens holder out of bent L brackets. Used some super glue to glue some rubber onto the bottom of the brackets to keep from scratching the polycarbonate lens. I dont think the outer edges are going to get very warm and thus the super glue should hold up just fine.

So I got really curious and wanted to know exactly how my light with a 35watt automotive HID bulb will stack up against the maxabeam. Since I finally got the lens holder made I was able to take it back outside again tonight without having to worry about beatles going up in smoke from flying into the bulb. Here are some of the images I took. The Maxabeam is on high in all the images.

Maxabeam on the right

Maxabeam on the left

About 150ft away from the lights. Maxabeam on the right.

About 300ft away from the lights. Maxabeam on the right.

The automotive HID is clearly much brighter as is evident in the first 2 pics. The Maxabeam still dominates on throw as is shown by the last 2 pics. I think this reflector is doing a great job at collimating the beam from a bulb with a much longer arc than a short arc. I'm thinking that means this will be a stellar performer once paired with a high output short arc.

That is some beautiful shots! Looks like you have a dark night sky and not too much light polution at your place? As for the beam, you will always get a tight hotspot and a bit of “corona” with a short focal length reflector as yours, but it will definitely collimate a lot more with a shorter arc.

We have the usual what appears to be about a 500watt Metal Halide security light in our yard as well as in several of our neighbors yards. Other than that the nearest bright lights are in the closest town about 5 miles away. Our night time sky is pretty clear. Just after I snapped one of the photos a really bright shooting star went streaking across the sky. One of the brightest I have seen in a while! Wish my camera had still been rolling...

It just kind of suprising to me how the maxabeam's reflector is several times smaller than mine and has a dimmer light yet is still able to out throw it. Arc length must have everything in the world to do with throw.

Just ordered the ballast but I have a few questions that I may have to call the mfg. about. So I found the ballast used on ebay. Its the Lumina Power XLB-300. Its rated at 300 watts. But when I look at the pdf file with the ballast specs it has a maximum output of 23amps and 25volts. If you do the math thats 575watts max output. If that's sustainable for a significant length of time I may be able to power a 500 watt bulb with this ballast. I'll write Lumina power to find out for sure.

I’m 99% certain that is a 300w max output supply. The values has to be separate max values (or a print error) On some xenon lamps, voltage can go down to 12 volt (12*25=300W) so that make sense.

So am I understanding you correctly to mean that if the ballast is outputting a max of 23amp the volts must be 13 volts or lower? And if the ballast is outputting a max of 25 volts then the amps must be 12 amps or lower? In other words it cant output 25 volts at the same time its outputting 23amps?

Correct. But you can of course contact Lumina power and ask them.

That makes sense. I sent Lumina Power a message just to confirm that its right.

Small update. Ballast is here. Got most of it wired up. Might be able to test it Monday!

Think I'm gonna ditch Xenon short arc. Too inefficient, hard to mount, and very big. Osram HMI bulbs look like a much simpler solution and they are more readily available and cheaper. The biggest advantage though is they are way more efficient. Seriously thinking about using the Osram 800W/ SEL but Osram does not list the arc length of the bulb.

I remember reading a post a while back on CPF about bulbs having a tubular arc chamber do not focus as well as bulbs with a spherical arc chamber. At such high lumens as the Osram HMI bulbs and the Phillips MSR youll get extreme throw either way but I was wondering if the Philips MSR bulb, though less efficient and dimmer, would out-throw the HMI bulbs because of the spherical arc chamber they have vs the tubular arc chamber that the HMI bulbs have. Anyone have any knowledge about this?

Have not heard anything about arc chamber shape should have any effect. As far as I know, the key to throw will always be luminance. The higher the better. And short(er) arc usually give you that. The MSR SA lamp (slightly dimmer) will out throw the regular MSR lamp. Different brands have different names for instance Osram HTI 705W/SE, Philips MSR 700 SA and Jenbo NSK700SA are all the “same” lamp with more or less the same specs. The only thing about the arc chamber I would think about, is that some lamps, (all of these) has the fill knob right over the arc. It will give you a slight artifact in the beam. But I have been running the MSR 400 watt SA lamp now, and I can’t say it bothers me at all. The other day I reached 6500 meters/4 mile with only a 7.9” reflector. That’s a decent result, artifact or not :wink:

To bad about your xenon plans :frowning: Didn’t you look into the 300 watt single ended lamp?

This is the thread I was referring too. http://www.candlepowerforums.com/vb/showthread.php?145887-Anybody-change-a-Maxabeam-s-lamp

I didn't look into the single ended short arc lamp. Overall though the effciency of xenon short arc is too low. Most of the regular 300watt short arc bulbs are only 7000 or fewer lumens. My FF4 can output that many lumens lol. I'm looking for something in the +13k lumens range and that'll require atleast 500watts or more in xenon short arc bulbs. I could find some 500 watt ballast but they were all 220volts AC which won't work over here.

Also there are no XSA bulbs t range that could be run in a horizontal orientation. I either had to go well below or well above 300 watts to get a bulb that could, and here again I run into the issue of them being too dim below 300watts, or too big and bulky and using 220volts above 300watts.

Anyway I've ditched xenon short arc and am looking into other means of achieving my goal. HMI, UHP, and MSR lamps all look like viable options that'll be much simpler and easier to deal with. I've emailed a few companies and am waiting to get word back from them before I make a decision on what bulb type I'm going to use.

I would like a light that has extremely long throw but at the same time I would love to have the maximum output possible too. HMI lamps have the highest overall lumens output but they are not short arc bulbs. More like medium arc length. Plenty of ballast options for HMI exist in the 500-1500 watt range and on the upper end of that range we are looking at 110k lumens output. Even if I didnt have the tightest beam out there the sheer output is extremely high. With such a deep reflector as mine I think the throw will still easily beat something like the maxabeam while being much more floody. Maybe I can strike a balance between a super thrower and super high output and still get super impressive results!

If I can get the ballast I want they can power a variety of bulb types (HMI and MSR lamps included) so maybe I can play around with different bulb types to see which ones work best for me. The MSR lamps are not quite as efficient as the HMI but they are true short arc bulbs with very high luminance intensity. In my reflector they would make a killer thrower especially the 850 watt bulbs with a 3mm arc length and 56k lumens output but the problem with them is the CRI is rather low and the CCTs are quite high at ~7500k. Not unusable but still not as great as the 5600-6000k found in XSA and HMI bulbs.

Ahh decisions decisions lol. If I get the ballast I want I'll likely end up with both the HMI and MSR, and UHP bulbs and test all three to see which one produces the superior beam.

Now that was a very interesting read about the arc chamber! Have never thought of that, then again, that maxabeam lamp is also the first short arc lamp I have ever seen with a tubular arc chamber :~ Now some of the metal halide does have it, but for the most part only the longer arcs. And then you of course have a lot of lamps with an extra tubular protective bulb. I guess you should steer away from them if you need that extra candlepower.

Yeah, join the club :bigsmile:

Exactly. That ruled out the HMI bulbs as all of them have the outer protective tube around the inner globular arc chamber.

Yeah LOL! Fortunantly I think I have narrowed it down to two ballast and two bulbs. My first choice is the Osram Lok-it! 1000 paired with the Elettrolab EDB1000 ballast. 85000 bulb lumens with a 5.5mm arc gap should produce some astounding results!! My second choice is the Osram HTI 705 paired with the Rotec ECG 800 ballast (Polari didn't you use this ballast in your vintage light with the MSR bulb? Super nice light BTW). Being that both ballast MFG's are overseas payment seems to be an issue especially for the Rotec. And Elettrolab does not sell directly to the public..sigh..Still got to work their salesman to see what I can get out of them.

Once I determine which ballast I can get then I'll know which bulb I can use. After I get the bulb I can resume building the light as I have done about all I can without actually having the bulb in hand. Deciding to go with a single ended bulb certainly made the build a whole lot easier. No troublesome returns wires or cumbersome mounts to deal with as supporting the bulb end near the glass widow would prove to be a HUGE pain LOL!

85.000 lm over 5.5 mm give you 15454 average lm pr mm… You won’t get that Xenon cathode peak, but it will be a killer light no matter what. You will get some spill, but also a massive throw! :party:

I know all about hunting for a ballast. (BTW, yes, I have both the 800 AC and DC from Rotec) So if you don’t get that 1000 W, I do have a suggestion for you. Since we are in overkill territory anyway, why not go for 1200 watt? Philips has a lamp called MSR gold 1200 SA/SE. 93.000 lumens, 5.5 mm arc length…
And here is a ballast: http://www.ebay.com/itm/Mac-2000-Electronic-E-Ballast-1200W-part-06100011-/291299571267
Note, you still need an ignitor for electronic ballast.

The lamp: http://www.usa.lighting.philips.com/main/prof/professional-lamps/special-lamps/entertainment/touring-stage/msr-short-arc/928174605114_NA/product
One more thing, and that goes for any lamp. Make sure you have enough clearance where the lamp pass the vertex hole. Running 4-5 kV cold start ignition, you also need 4-5 mm clearance from the return wire to avoid an arc over.
PS, you need a glass lens running this much power, tempered or boro plus good cooling. Not only the lamp, but also the reflector as the aluminium coating doesn’t like to much heat.
EDIT: Max temp for the reflector coating is 250 F. I sent you a PM.

The automotive HID bulb I used has a 4.2mm arc length. So Ill to get a slightly wider beam with this bulb than with it.

Okay Okay. I was originally going with a 300 watt XSA, then I bumped up to 500, then back to 300, then up to the 700watt HMI, and now I'm at a 1k watt HTI. And you now you're trying to talk me into 1200watts! By the time the light is complete Ill be at 20kw!!! LOL JK

Any way that is a good suggestion! I had wanted to go with the Elettrolab EDB1500 watt ballast and the Osram Lok-it 1400ps. 120000 lumens with a 4.5mm arc length, but the 1500 watt ballast is 220 input so thats why I dropped back down to the 1000 watt. That ballast you linked to though has 105-264 voltage range so I will definitely keep it in mind! Thanks!

The vertex hole on my reflector is 35mm. The Lok-it 1000 has a 21mm arc chamber width plus probably 2-4 more mm for the return wire. Thats gonna put it right at 4-5 mm away from the edge of the hole.......lets hope it doesn't arc. Otherwise I may have to find some high temp electrical insulation to prevent that. Wouldn't electrically insulating the ballast from the rest of the housing prevent the bulb from arcing though? If so I could just mount the ballast on some rubber pads to insulate it from the housing.

Regarding the arc, there is another important factor at play here, and that is arc width. The arc will be much wider on that 1-1.2 kW lamp compared to the tiny car HID, so a big part of the arc will be out of focus, meaning more spill. But either way, the throw will still be colossal, don’t worry about that!

As for HV, I’m no electrical engineer, I just like to make things… The 4-5 mm distance is the normal rule of thumb for a cold start system. When it comes down to the HV stuff and my lack of knowledge about that, I prefer a little bit extra insulation and/or distance, and never have to worry about any issues. I prefer it that way :wink: As for the vertex clearance, you can always cut/file a small groove or use some extra insulation if you not comfortable with the way it looks.