Wednesday, October 13, 2010

DIY searchlight housing for 1000W xenon arc lamp

Original test run of 1000W arc lamp:
http://benkrasnow.blogspot.com/2010/04/first-test-run-of-1000w-osram-xenon.html

I finally finished the 1000W xenon searchlight project that I started earlier this year. The power supply is a slightly modified arc welder coupled with an automotive ignition coil for the starting pulse.


This is the searchlight's beam shooting skyward behind a large pine tree in my back yard. The beam is very difficult to capture on video.

32 comments:

archeleus said...

You explained that pretty well and it's awesome.

patman2700 said...

Impressive project! Now the only thing left to do is add a swivel mount. ;)

Are you an electrical engineer? Where did you learn how to build these high-voltage circuits?

Anonymous said...

You know you can get those lamps with up to 7kW power? :-) :-) Could ask a cinema if they have some left with ignition problems. Then you just need to increase your ignition voltage and they will ignite anyway... And make shure NEVER to stand in front of the device. Those short arc lamps tend to explode quite regularly.

Anonymous said...

you cannot see anything beyond 30hz. what you were seeing are the beats created between output light and the ambient light at (60Hz). most likely the flicker is still due to mains 60hz cycle (but is actually 120hz on the output due to a full wave rectifier). filtering the mains input AFTER the full wave rectifier of the welder circuit should work as well. cool project none-the-less.

Ben said...

Thanks for the comments. I have a BS in mechanical engineering, but often do circuit design for my day job. Unfortunately, college engineering curricula don't really prepare students to actually build anything. The vast majority of coursework covers background information and theory, which is useful, but only in moderation for most engineering jobs. I think many professors feel that teaching practical design is only for technicians and vocational schools. It's a shame. However, there is so much useful information available on the internet, anyone who wants to learn practical design can do so very easily and just get the college degree to make employers happy.

I think there are even 15KW bulbs for iMAX projectors. The bulbs are water-cooled and truly massive.

Humans can definitely "see beyond 30Hz". Set a strobe light to 30Hz, and the flashes will be extremely apparent. In the early days of CRT monitors, the low refresh rate of 60Hz (or less) caused a great deal of eye strain, and the monitor flicker is instantly apparent to most people. Likewise, fluorescent tubes run by a magnetic ballast flicker at 120Hz and this can cause eyestrain too, but many people cannot immediately detect the flicker. Tungsten lights do not flicker because the filament doesn't cool down between AC cycles. I measured the output of my high-current supply, and there is almost no 60Hz ripple under load. The problem was definitely the high frequency pulses from the inverter circuit.

Anonymous said...

If you can't spot deer with that, you're blind!

Anonymous said...

@Anonymous: The deer will be blind before.

Anonymous said...

I'd love to see how this light performs over some distance. Could you do another video where you actually light up the environment?

Anonymous said...

Ok....
so take one of those 32 inch LCDs apart, mount the LCD in front of the "reflector", and create the most powerful DIY-projector of all times... maybe some giant lenses are needed ;)

Dave J. said...

This might sound silly but why did you not go High Pressure Sodium? Been pricing Xenon bulbs and comparing Lumens per Dollar. Found some 1,000watt HPS bulbs that put out 110,000 lumens for $23. Would not not see the beam at the color temp of HPS?

Ben said...

I will try to get some more videos of the searchlight in action. Stay tuned.

Dave, yes this would work well with HPS, metal halide, mercury vapor, etc. Xenon arc lamps do not have an inner glass envelope, so it better approximates a point source of light, but the main reason that I chose xenon is because I already had the bulb from a surplus sale. I paid almost nothing for the bulb, and eventually got around to building a supply and housing for it.

Herdir said...

can we call batman with it ?

Ben said...

I tried the bat signal idea a couple nights ago and found a problem with my mirror. I bought the parabolic mirror from Edmund Scientific, but it turns out that the shape is not a perfect parabola. It has a slight discontinuity in the curve, and so the searchlight output beam is not perfectly collimated. When I place something (like a bat-shaped piece of wood) in front of the searchlight, the beam just becomes a little dimmer without holding the shape. I need a more perfect parabolic mirror.

KingJacob said...

Hello Ben,
My name is Jacob Shiach and I am putting together a magazine for "amateur" scientists. Would you be interested in putting together something for the first issue? If so, my email is kingjacob (at) gmail.com

Anonymous said...

Is there a printable version of the instructions?

Ben said...

Anonymous, there aren't really any instructions. This is simply a blog post describing something that I have made. I'm afraid that I do not have time to write detailed instructions, but if you have a specific question, please feel free to post.

Tim said...

I've been involved with a Haunted Hayride for 11 years now for our non-profit club. I've look for a search light several times, GLAD I looked again. I have an old 220 arc welder, can it be used? Is there any other bulbs that can be used with similar results?

Ben said...

Tim, you could build a great searchlight with a high-quality parabolic reflector and any bulb that has a very small light-discharge area. I got the reflector from Edmund Scientific. You could try a metal halide, mercury vapor, or even high-pressure sodium lamp. It might be possible to run a HID lamp from your welder, however the ballasts are not too expensive. Good luck!

Anonymous said...

Hi Ben,

You're absolutely right about flash rate perception. I'm the IT guy in a neurologic research lab. I was surprised to learn that the eye and the first layer of processing by the brain (L1) can handle rates of 90Hz and beyond. Its the later stages of our brain that limit our conscious perception to the lower rates.

I should also warn that arc lams emit a *LOT* of UV, and are harmful to the eyes. If they feel dry or itchy after exposure, it's time to turn it off!

Awesome work on the lamp. Ever since I was a kid I was fascinated by klieg lights. Every time I saw on I'd make my parents drive until we found it!

Anonymous said...

Hello Ben. We have been using the parabolic reflectors from HB opticals for our 1000/1600/2000W Xenon searchlights. (http://www.hb-optical.com/English/reflectors/parafl.htm)
The P400-60 and the P356 are giving the perfect beam for these lamps as well as for the HMI 1200/2500W SE G38 lamps. There are also manufacturers in the US like Phoenix Electroforms which produce high quality nickel-rhodium coated parabolic mirrors up to 20" which works good for these applications.

Anonymous said...

Nice to see your Light Ben,its great!We are also making Search Lights for the marine industry and now are struck up in one project in which we are using a 1KW Xenon Lamp and want to achieve a 80Mn cd spot beam and with a 2KW Lamp an 120Mn cd power is desired.We have tried a lot of reflectors and result is not coming,can some one suggest us which reflectors to be used.

Ben said...

Anonymous, finding a parabolic reflector that has high optical quality and can withstand the heat of the xenon lamp is difficult. I bought an anodized aluminum reflector from Edmund Scientific. The reflection was slightly diffuse, so I removed the anodize coating, then polished the bare aluminum. Unfortunately, the reflector's geometry was not perfect, and the resulting beam was somewhat collimated, but it could have been better. I also found plastic (acrylic) parabolic mirrors, which might work, but could melt in the heat of the lamp housing. The Edmund product was the best result from my searches.

Anonymous said...

To "Anonymous" January 23, 2011: It is not a problem to reach 80 Mn cd through a 1 kW lamp but the size of the reflector is the limitation. To reach such power output you have to go for a reflector of a min. 20" diametre size (even if you go for the nickel-rhodium plated version) instead of the normally used 16" for the marine 1kW Xenon searchlight units. Which make the construction not suitable for high vibration mounting conditions etc. You can also forget about reach 120 Mn cd power from a "normal suitable size" marine searchlight through a 2 kW lamp. The reflector size will be too big. You can read more about light outputs from one of the leading manafacturers of marine searchlights of this size Francis. http://www.francis.co.uk

Jens Birch said...

Awesome Searchlight project. I think I could manage the electronic part but I have searched all over the www for a parabolic reflector... May I as where you got yours?

Thanks for a veri inspiring video!

Cheers, Jens

Ben Krasnow said...

Jens, I bought the reflector from Edmund Scientific. It is anodized aluminum, and is fairly low in terms of optical quality. The surface finish causes a fair bit of light to be scattered. I laboriously removed the anodization, and polished the bare aluminum. This helped a little, but having a true parabolic mirror would be better.
http://www.scientificsonline.com/large-parabolic-reflectors.html

Jens said...

Thanks Ben.

They are less expensive than i thought and you are right, they look a bit matte even on the promotional photo.

I have tried polishing anodized Aluminum before and my experience was that the a shinier surface could be obtained but it oxidized quite fast and became worse than before.

Anyway, I think I'll get one and see how it performs. It should be possible to judge how small (large) the focal point is by focusing the sun onto a piece of ground glass. If it is larger than the discharge, then it might be better suited for e.g., s halogen lamp.

Cheers, Jens

Anonymous said...

I second what the above said. A LOT of UV! I assume by looking at the raw design you have no UV filter in place. Really anyone near that thing needs protective eye ware, and cover every inch of skin... These lamp produce massive amounts of UV A, B and C! All will do damage to any exposed tissue especially the eyes. Even being behind the the reflector isn't safe for any period of time.

Manolo Maravillas said...

hello very good system, I have 2 lamps osram xbo 3000,,, operating at 30V and 100 amps, you think you could feed a dc inverter welder 160 amp,,,,???
there are any modifications apart from the ignition system that I have.
email: solucionesopel@hotmail.es

Brandon said...

Hey Ben, I'm looking to build my own spotlight for my company, thanks for all the help! I know you don't have time to write out all the instructions, but do you happen to have a shopping list of all the equipment you used? Between that, your excellent video, and my BS in Electrical engineering, I should be able to take it from there (although what you posted about College degree's being all about theory is absolutely correct, so if there's anything particularly dangerous, I would love a heads up)

Thank you!

Ben Krasnow said...

Here's a rough shopping list:

Xenon short-arc lamp (eBay)
DC arc welder (Harbor Freight)
Reflector (Edmund Scientific)
Ignition circuit (car ignition coil, toroids, etc)
trash can
cooling fan

The lamps are under high pressure, and are an explosion hazard. Of course, you are also working with high-currents and high-voltages, so the usual warnings apply there.

Anonymous said...

Hi Ben, great job! Can you please clarify how did you insulated high voltage ignition circuit from main power circuit? Did you put a secondary winding of an ignition transformer in series with power supply and lamp or in parallel with lamp? Does a welding machine power supply has any high voltage protection in it? Thanks in advance!

Ben Krasnow said...

Anonymous, the ignition transformer (custom toroidal thing that I wound) is in series with the main power circuit. I put a capacitor across the output of the welder to prevent short, high-voltage spikes from reaching it.

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