1000W Search Light – Now Build A Bat Signal

Forget flashlights, and leave those burning lasers at home, [Ben Krasnow] built a search light using a 1000W xenon arc lamp. That box you see on the side of the trash-can housing countains a starting circuit that shoots 30 kilovolts through the xenon lamp to get it started but it is separate from the power supply. [Ben] started experimenting with the lamp back in April but recently finished the project by using the inverter from an arc welder to get the 50 amps at 20 volts needed when the lamp is on.

The insert on the left of the image above is an outdoor picture of the beam. You can make out a tree at the bottom. Take a look at the video after the break for a full walk-through of the circuitry and some test footage of the finished product.


41 thoughts on “1000W Search Light – Now Build A Bat Signal

  1. Retina burn – you’ll enjoy it.

    Funny thing about laser galvos – they don’t know where the light comes from. It won’t be well collimated, but he can build a pretty decent pixel writer using this and some galvos, or do moving signs using bulk r/c servos and stick on mirrors.

    If he wants to be seriously old school, a bunch of 12″ x 12′ mirror tiles with a bit of black hi-temp paint can be assembled like a ferris wheel and will allow him to project “moving pictures” on the sky.

    The mechanics of this aren’t complex, but the demo I saw as a kid was a guy who used plywood, expoxy and duct tape to fit big mirror tiles on the hub with tire of a large truck rear-end and then drive it with a motor. He had to screw around to get the beam right, and the tiles may have been smaller (it was a long time ago) but I thought they were large.

    Voila! Stick figure animation on low clouds. I think he used a small vietnam era search light, YMMV.

  2. That man is insane. I worked as a projectionist for years — those quartz envelopes in a xenon bulb are kept at VERY high psi. To handle a bulb like that without extreme caution and leather protection, let alone full face mask is crazy. They take a tiny bump and bam, ‘glass grenade’. Having the front of that housing unprotected is just poor. A bug shitting on the bulb while hot would cause it to fail dramatically.

    The oil from a fingerprint is enough opacity on the bulb surface to cause the bulb to fail. There’s a reason they ship in explosion-proof containers.

    Granted; I worked with the 5-15k watt versions, so 1000 seems quite small, but still EXTREMELY dangerous.

    OTHERWISE: Great project!

  3. The DHS (Department of Homeland Stupidity) shall be knocking on your door shortly for committing terr’ist act of making a light. Such creativity and independent thought is a Clear and Present Danger to ‘Merica and our fear-based belief systems. No need to call your lawyer, we have a nice resort in Cuba ready for you where the Constitution does not apply.

    Great project, BTW. ;-)

  4. Just a random question, but I don’t think this guy is using all of his brain cells… why on earth would you be using a screwdriver as a pointing device–especially on something with THAT much juice going through it? Otherwise great project.

  5. @Jason
    “Voltage doesn’t go THROUGH anything. Voltage is a difference in potential ACROSS something. This isn’t the first time you have made this minor and very common mistake.”

    I always laugh at statements like this. Some people can’t handle abstraction, and try to make up for it by being pedantic. If Jason wants to be precise, he needs to discuss this at the lowest level that makes sense.

    Voltage is electric potential energy per unit charge, which we call volts but mean joules per coulomb. He pretends that electric potential is a better way to deal with the topic, but this must be distinguished from electric potential energy by noting that the “potential” is a “per-unit-charge” quantity.

    Saying that “Voltage is a difference in potential ACROSS something” shows that Jason is OK with using SHORTHAND for describing the work required to move a charge. Voltage is not the difference in potential, but the amount of work that has to be… well, Jason doesn’t have time to deal with charge and Coulomb’s Law, because Jason chose to use the layman’s description of what is going on.

    And yet he’s bent out of shape because the author said the voltage goes through a circuit, which is not a mistake, but rather a SHORTHAND term used by many people who learned electronics by connecting things together to make a circuit.

    Jason, if the guy’s description of the process were wrong, it’s perfectly OK to correct him. But in this context, you’re being silly. It’s like getting in his face about light being wave-like in nature when you know it’s all particles.

    This guy is trying to become ray charles one tiny arc discharge at a time, but no one imagines for a minute that his internal understanding of electricity is wrong.

    If you want to do him a favor, buy him a white cane and some dark glasses.

  6. Disclaimer: As a 10 year old who found a box of 1910-30’s science magazines, I dismantled two batteries, sharpened the carbon rods inside, and with the help of innate childhood stupidity proceeded to strike an arc – and then nearly caught myself on fire. Very cool.

    But it made my eyes itch. There is a general trend here, btw. At 8, having just read a book about Edison, I tried to make a filament bulb using a clear glass vitamin jar and some wire. I tried to create a vacuum by sucking the air out with my mouth. The spirit of Darwin was always hovering nearby, as he still does.

    I did in fact manage to get a lightbulb filamemnt made by putting cotton thread in a toaster (I wasn’t allowed to use the stove) and when I plugged it into the wall, my home made lightbulb glowed very brightly.

    “I’m so cool!” I thought. (and still do, Sadly)

    Seconds later the filament crumbled, the wires shorted and the wire blew up. Since I was holding the wire in my bare hand, it burned a lovely “U” into my thumb. The black residue around the electrical outlet was impressive, but after I regained my senses, I hid everything, put an ice cube on my thumb and went out to play.

    Later that day I talked a 12 year old neighbor girl into renting me part of her basement bedroom for my biology lab… because my mom wouldn’t let me have one (I was 8 and too young for a lab, she said.) and I really needed one for my work.

    I was 8. To this day, I have no idea what my work was going to be, other than involving white lab coats and a hare-brained scheme to generate oxygen from algae. Really, I didn’t have anything other than a vague idea that I would keep my rabbits and chemistry stuff in her bedroom. We agreed that the rent would equal my lunch money, and the deal was struck.

    She helped me drag a small table into her room, and promptly got undressed… to uh, help me. I think she had other experiments in mind, but I was very determined to conduct my own research, which didn’t require naked girls, as far as I was concerned. I remember telling her that she would have to get a lab coat if she ws going to help.

    I was far more concerned about going and getting my 3 test tubes, my batteries and a fish pump (it made bubbles in the test tubes) for immediate use. I had everything installed and bubbling away when her parents came home. She ran out of the room; the next day she came to my house and said I could have my stuff back because her parents didn’t want a lab in their basement.

    I think I dodged a bullet.

  7. @bilbao bob: And… why should I care about your obviously bullshit stories of renting basements for biology labs and even more some girl 1.5x your age trying to get with you when you were eight years old? Even if you believe those fantasies, they’re still not relevant at all.

  8. bilbao bob: way to stomp on him. liked the story too, reminds me of someone i read about that made a water cannon out of schedule 80 iron pipe and a Teflon ball, and several thousand volts, that wouldn’t be you would it?

  9. I’ve worked with Xenon Arc Lamps as well, and they are like glass grenades when they go off. You need to be very careful with them. Especially if they are hot. If I remember right the ones we had were pressurized to 1000 Atm.

  10. @Rvnknight
    While not the best tool for the job the screw driver handle is insulated and he’s using his right hand to point with so if he does complete a circuit his heart should be alright.
    The breakdown voltage for air is ~76kV/inch and his hand looks to be atleast and inch away from the shaft/handle junction so I don’t think he has too much to worry about since the startup circuit puts out ~45kV at 100% efficiency. Also hopefully the lamp is unplugged. All the same you’re right he should kick that habit.

    Growing pot is still a crime, it’s just not enforced in your locality. Marijuana is a Schedule 1 drug, ie illegal on a Federal level. States can have more restrictive laws than Federal laws but they cannot be less strict. Having said that Xenon arc lamps put out a spectrum very similar to natural daylight, so given the high concentration of light you would sunburn your plants. This lamp puts out ~1kW/m^2 and the Sun puts out ~6w/m^2 or 166.66 times as much energy per square meter.

  11. @bilbao bob: I love you little stories – you’re one interesting guy. You should be writing this stuff on a blog if you’ve not already got one.

    I too had a strange facination about producing oxygen from pond weed after I saw it in a book when I was a kid. The book gave me the impression you could produce bucket-loads of this stuff from a handful of pond weed – it wasn’t until I was about 14 when I saw a real-life setup in secondary school. Man I felt so cheated because in reality it actually only produced a few bubbles throughout the whole day.

  12. This reminds me of my 8,000,000 candle power “pizza driver” light I made. I was working for a large pizza delivery company that had an annoying mascot and a 30 min guarantee years ago. I worked in a notoriously bad area and there was a distinct lack of porch-lights and readable address numbers so I took a headlight (the outer acrylic part) and added several 2 mill CP bulbs. I had to run a separate battery and charging circuit and could only turn it on for short <1 min bursts or it would melt. One day I came to an intersection (4 way stop signs) and someone was blinding me with a light so I Blasted them with mine….. oops, it was a police officer! I just turned off my light and drove away, hey I was working. I'm sure it was several minutes before he could even see enough to pull through the intersection, no way he could follow me or identify me other than "He was carrying the SUN!" It was also great for those SUV's with misaligned extra bright headlights that like to tailgate little hatchbacks at night.

  13. @Chris –
    Man, I wish they were fantasies. I really do. I was probably the only kid interested in space who didn’t want to be an astronaut. No, I wanted to be the guy who built the spacecraft and designed the equipment they used.

    You know how kids who discover sex too early or get molested by some adult are messed up for life? I’m that kid, except that a drunk jazz musician taught me to read and write when I was four. A very bad idea, in retrospect.

    You try going to kindergarten when you’re reading third grade books while everyone else is learning to color the letter “N”. I’m not even that smart – I’m more or less the intellectual equivalent of that chain-smoking baby in the phillipines. Instead of cigarettes, someone gave me books and I became a junky who had to know more.

    I wish my stories were bullshit. I have a strong compulsion to try and do everything one can do in life, and time is running out for me.

    @pizza dude-
    Ha! I have a similar story. I had auxillary brights for a while on an old car. I don’t know what the fascination with bright lights were – it seemed like all my friends were melting paint on garage doors at the time.

    Anyway, my stupid setup was a row of four 28 volt military aircraft landing lights (swiped from a dump) connected to batteries in my trunk – basically a rallye setup, and driven by a contactor. One day I was coming home and some arse had parked in the middle of the street with his brights on.

    So I turned on mine, thinking I’d show the jerk how rude it was. He turned his off. I turned mine off. He turned on his police lights and indicated that I should park. After much furious bowing, scraping and general kissing of his nether regions, I was let off with a warning.

    I just disconnected them. I never had the giant flood light, but I know how nice it is to make it noon at ten-thirty pm when you can’t find a place.
    I wish I had that for the back roads here, where there is no moon and no stars for most of the year, and they turn off street lights to save money.

    @Dave mcDave –
    I wonder if it was the same post-sputnik book about the kids who built an oxygen tent for a chimp with pneumonia using algae. That book should have had an FDA warning on it – along with Tom Swift books – because it convinced seven year old me that even kids could do anything they had to if they just studied and were willing to make mistakes.

    The childhood biology lab experience was directly influenced by that book and “the germ hunters”, and about three boxes of circa 1966 space program propaganda for children. Soon I had a dozen mayonnaise jars with pond scum (I couldn’t distinguish algae from any other green slime) and little aquarium tubes all connected together and supposedly generating oxygen. I had no idea what I was doing – in essence, my science was cargo cult science… but I was in fact “doing”.

    Yeah, I’m guessing she’s probably fat, old and likely has great-grandchildren and a big collection of problems I couldn’t solve. But yes, I’d like to have seen her in her 20’s. You know, I don’t even know why I suddenly remembered the lab story. Oh yeah, the exploding light bulb trick.

    How the hell I made it to 9 is beyond me. Thank god I didn’t read about arc lights until I was 10. Maybe the TSA should profile 8 year olds with a copy of the “Golden Book of Chemistry” and access to college dumpsters. You want examples?

    I remember finding a 30.06 rifle bullet and thinking I should be able to convert it to a small solid rocket if I could ignite it. My dad confiscated it when I asked him if he could help me drill a hole in the bottom of it so I could put a fuse in. This was pretty typical for me.

    A little girl I knew was given a pocket watch by her grandfather, and she proudly informed me that it had 18 rubies in it.

    I knew that ruby was used to build lasers, so I immediately started offering her almost everything I owned in trade for the watch so that I could start building my laser. I knew nothing about lasers other than they were science, and I needed one.

    Ruby rod vs tiny chips of ruby used as bearings? Access to strobe lights? Bah! Mere details. Thank God I had nothing of interest to her. So, I was pretty active in science, but it wasn’t really science. Just an 8 year old with a fetish for technology that kept getting worse for a few decades until I realized it was a fetish.

    But I suppose chris won’t like these stories much either… :)

  14. It’s kind of funny. People probably see 1000 watt Xenon lamp and are wowed by the wattage, but theatrical lighting folks think that ain’t nothing, being as your typical ellipsoidal light runs at 750watts and your PAR64 (flood light) runs at 1000watts as well… then you have the lovely 5000 watt fresnel. Awesome build though! I might make one myself.

  15. @Kevin and John
    “1000w metal halides are pretty common.”

    Yeah, but they’re not made out of garbage cans!

    You, know, this thing would probably make a heck of a jerky/meat smoker. I’ll bet it could make sterilized shoe leather in 30 minutes from an average T-bone steak.

  16. I know this is a bit sideways, but after seeing this and thinking about the laminar water jet, could someone speculate on the possibility of producing a laminar light jet using something like this project as a source?

    My boundary layer photonics are a bit rusty, so any educated response is appreciated!

  17. Ben your search light is amazing, as is your commentary which is grounded and lacks the umm’s and aaarh’s that some geeks might have :)

    @bilbao bob love the stories, please start a blog :)

  18. Yep, building 1000W + lamps is fun, i made my first one with a wooden box and an old microwave oven, one year later I was showing it off to NASA, plasma scientists and Queen Elizabeth. If I had a “safety first” approach I would not have built anything and my life would have been so boring in comparison, just saying … Clive Wiing – Sulphur Plasma Specialist

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