Carbon-Arc lighting, interested to know anything

[Tin Can]

I saw a movie crew, using a very bright light connected to what looked like a welder or battery charger. It was blowing out the Sun and seemed different than a standard arc-welder in color and intensity.

What is known about current usage? How much juice do they need?

They also were used for old movie projectors.

Found one on eBay...


http://www.ebay.com/itm/Vintage-Regalite-Carbon-Arc-Theater-Spotlight-Early-1900s-WORKS-/121111679033?pt=US_Stage_Lighting_Single_Units&hash=item1c32d19039

Always curious Randy

[Mark Woods]

Since it's plugged into the wall (maybe not?) it's drawing 20 amps. I would confirm that with the seller. The biggest problem is going to be getting the carbons to run it. Mole-Richardson sells them, but you may have to modify them to fit this unit. The big arcs can draw over 100 amps and the little cylindrical object on the stand is to reduce the voltage to 90 v., but the amperage is over 100. This unit is a small unit. I noticed the lens was not on the front of the unit. This is BAD! The arcs produce a lot of UV and you can burn your eyes. This is really irresponsible for the seller to show the unit this way.

[Bill_4606]

Ah, that takes me way back to the time I built my own carbon arc furnace. I didn't have the transformer to control the current so I used a glass pan filled with salt water. Children:do not ever try that at home, or anywhere!

In high school, I ran the projectors at a local drive-in which used carbon arc lights. After about the third running of The Love Bug, I started wondering what I could do with all that energy. I never could get a good temperature measurement from my furnace .. But let me tell you, it was hot. Still it was a great science experiment. I learned a lot about the dynamics of striking and maintaining the arc and how it related to current draw. I also learned that my mother had a lower than expected tolerance for my experiments.


I actually was able to draw on that experience in later life when I designed a device that used similar principles. The transformer increases the voltage so a good arc can be drawn across a gas field -air in this case. It also doubles as a current limit when you strike the arc due to core saturation. It was a much better controller than my pan of salt water.

Bill

[Bruce Watson]

I saw a movie crew, using a very bright light connected to what looked like a welder or battery charger. It was blowing out the Sun and seemed different than a standard arc-welder in color and intensity.

If you saw this recently, the instrument was almost certainly what's called an HMI (http://en.wikipedia.org/wiki/Hydrargyrum_medium-arc_iodide_lamp). It's an arc type lamp with about the same efficiency as a fluorescent lamp (which is also an arc type lamp). It's typically used in a housing with a focusable fresnel lens, and when used outdoors during daylight hours is typically used in fairly high wattages (anywhere from 575w to 18kw or higher). The point is to simulate the quality and quantity of the sun's light, while controlling the location (the earth has this nasty habit of continuous rotation that makes the sun's relative position seem to keep moving, which can play havoc during a day of shooting exterior location work).

The thing that looked like a welder / battery charger was its ballast. An HMI ballast for a large instrument can be quite large and very heavy, especially the older style magnetic ballasts. They get moved about using hand trucks.

You can use HMIs for still photography much the way carbon arcs were used.

[Tin Can]

They shoot the TV show Chicago Fire bar scenes close to me. This was the brightest light I have ever seen. 18k would have needed a gen trailer.


If you saw this recently, the instrument was almost certainly what's called an HMI (http://en.wikipedia.org/wiki/Hydrargyrum_medium-arc_iodide_lamp). It's an arc type lamp with about the same efficiency as a fluorescent lamp (which is also an arc type lamp). It's typically used in a housing with a focusable fresnel lens, and when used outdoors during daylight hours is typically used in fairly high wattages (anywhere from 575w to 18kw or higher). The point is to simulate the quality and quantity of the sun's light, while controlling the location (the earth has this nasty habit of continuous rotation that makes the sun's relative position seem to keep moving, which can play havoc during a day of shooting exterior location work).

The thing that looked like a welder / battery charger was its ballast. An HMI ballast for a large instrument can be quite large and very heavy, especially the older style magnetic ballasts. They get moved about using hand trucks.

You can use HMIs for still photography much the way carbon arcs were used.

[Mark Woods]

Great post Bill. And Randy, 24K HMIs are made that they're a terrific light. It's common for a production that uses these instruments to to have at lease on 1200 amp generator, and it's not unusual to have more than one generator of that size or larger. When I first got into the business arcs were common on set. One generator that often went out with them was from a diesel WWII submarine. The diesel powered the generator that was DC. I was in it's own 40' trailer. Amazing times....

[Tin Can]

I had forgotten http://drmegavolt.com/ whom I saw at Burning man 2000. He performed with 2 giant Tesla coils mounted on a semi trailer towing a huge generator. He did his show while the rig slowly drove, I think to keep people off the rig.

Unfortunately I did not have a camera.

It was something else seen live.

[vinny]

They shoot the TV show Chicago Fire bar scenes close to me. This was the brightest light I have ever seen. 18k would have needed a gen trailer.

I work with that cinematographer from time to time. The biggest light we usually carry is an 18k hmi fresnel or 18k hmi pars which are huge as well. Almost all hmi's have a separate ballast as already mentioned. There are bigger lights, 50k & 100k rectangular units made by Softsun. They require their own generators running at 480volts.
There are a couple gaffers that still use arcs (because they own them) but its pretty rare. I haven't seen one in the 10+ years I've worked in the industry.

[Bill_4606]

Yes! And how about Arcattack? Imagine, modulating the air to produce sound with an spark generator like a Tesla coil!
http://m.youtube.com/watch?v=B7yqn89jwZo&feature=related

Ionizing gas atoms is a BLAST!

To keep this on topic... How about interfacing an 8x10 magic lantern arc lamp with MIDI device and Tesla coil to produce a spectacular audio visual experience?

[David Swinnard]

Don't take two D-cell carbon-zinc batteries apart. Don't take the internal carbon rods from said batteries. Don't take an old lamp cord and strip a few inches of insulation from the ends.

Finding a couple of pieces of wood to drill appropriately sized holes for the carbon rods is likely OK - you could make something useful from them, but don't shove the carbon rods into the holes. If you do this it may lead to finding a third piece of wood to smack the other two bits onto - carefully separating the carbon rods you shouldn't have pushed into the holes, by about "that" much. Don't EVER wrap and tape the stripped ends of the lamp cord around the outboard ends of the carbon rods. Most especially don't avert your eyes from the evil assembly you shouldn't have made and plug the end of the cord into the nearby socket on the front porch.

If you do, there might be a very bright flash, and a loud noise followed by an even louder noise of a bellowing father wondering what the !@#$ happened and why the lights went out. You might escape a spanking 'cause you're just a bit to old to be spanked - maybe.

You might also learn some new words.

Don't

[Leszek Vogt]

Wow, David....that has mad scientist written all over it. I take it that it would be safer to do sand castles.....by the way when is that happening ?

Les

[Tin Can]

Arcattack is very tame compared to Megatron. Maybe 100 times the power, it cracked loudly, it was visible for miles.

I gotta see a 100K arc light running, it must be something else. Softsun indeed. Checked the website, not very good demos.




Yes! And how about Arcattack? Imagine, modulating the air to produce sound with an spark generator like a Tesla coil!
http://m.youtube.com/watch?v=B7yqn89jwZo&feature=related

Ionizing gas atoms is a BLAST!

To keep this on topic... How about interfacing an 8x10 magic lantern arc lamp with MIDI device and Tesla coil to produce a spectacular audio visual experience?

[Tin Can]

I used to use a 480 volt arc welder all the time, nothing like big stick welding, except those 100K arc lights...



Don't take two D-cell carbon-zinc batteries apart. Don't take the internal carbon rods from said batteries. Don't take an old lamp cord and strip a few inches of insulation from the ends.

Finding a couple of pieces of wood to drill appropriately sized holes for the carbon rods is likely OK - you could make something useful from them, but don't shove the carbon rods into the holes. If you do this it may lead to finding a third piece of wood to smack the other two bits onto - carefully separating the carbon rods you shouldn't have pushed into the holes, by about "that" much. Don't EVER wrap and tape the stripped ends of the lamp cord around the outboard ends of the carbon rods. Most especially don't avert your eyes from the evil assembly you shouldn't have made and plug the end of the cord into the nearby socket on the front porch.

If you do, there might be a very bright flash, and a loud noise followed by an even louder noise of a bellowing father wondering what the !@#$ happened and why the lights went out. You might escape a spanking 'cause you're just a bit to old to be spanked - maybe.

You might also learn some new words.

Don't