Carbon Arc Flashlight

[SteamKit]

Mentioned this in another topic, but I'm curious if anybody else reckons a carbon arc light driven by 6v and electromagnetically controlled like the arc lamps of olden days would be a feasible steampunkish flashlight. I will note that arc lamps -are- indeed period, having been invented around...If wikipedia serves me right around 1802

[Daemon]

It sounds like the methods of regulating the proper gap can get complicated so I would suggest perhaps an attempt at duplicating something like the Yablochkov candle which self regulates and seems relatively compact. I am unsure what the voltage/current requirements would be though.

[SteamKit]

Those surely are neat, and probably would be easier to build. I've seen some simpler sorts of carbon arcs, only reason why I first thought of them is well, the Yablochkov candle's are a one time use. Then again, it'd be more of a prop..

[Commissar Swoosh]

I hope we aren't getting all of our knowledge from wikipedia, it is such a flawed site.

[SteamKit]

I hope we aren't getting all of our knowledge from wikipedia, it is such a flawed site.

?

[Great Bizarro]

Would the candle invention work if you were to place a momentary switch between the blocks instead of a fuse and short it briefly to start the circuit. I am not sure what purpose the plaster played in the circuit. I have used the carbon from an old D cell battery and a pair of 6v golf cart batteries to weld with, just don't stare into the light.

[Kew]

I hope we aren't getting all of our knowledge from wikipedia, it is such a flawed site.

But damn good for technical and mathematical information. Given that this is what we're after here, it's a good start.

[Offlogic]

Would the candle invention work if you were to place a momentary switch between the blocks instead of a fuse and short it briefly to start the circuit. I am not sure what purpose the plaster played in the circuit. I have used the carbon from an old D cell battery and a pair of 6v golf cart batteries to weld with, just don't stare into the light.

The fusible link is for starting the arc (metal blows, leaves an ionized trail to prime the arc). The plaster was an inulator that would just ablate.
Never heard of these "candles" before (love the SPF!), but they are very interesting as Victorian disposable lighting apparatus.

[Doctor When]

"Burning" carbon rods in this way sounds like it ought to take a fairly high voltage and current. I dread to think how big the battery would need to be to run one for more than a few minutes!

[SteamKit]

Doesn't take as much as you'd think, current seems to be more important than voltage. The 20v on my power supply was enough to throw an arc so bright I couldn't see right for nearly an hour, massive throbbing spot in the center of my vision. What I'd like to power it off of is a lantern battery, not sure if those have a special name in the UK but they are a fairly high current capacity battery that operates at 6 volt, standing roughly...I'd guestimate about 5 inches high, 3 inches on each side. This flashlight by no means would be small.

[J.Wilson Esq.]

I agree, current is more important than voltage. 6 volts is easily adequate to strike an arc, but it requires quite a bit of amperage to sustain it for very long. A lead acid battery of substantial size could be used, but it's hardly portable.

Probably for a powering a flashlight-scaled device, a Lithium-Polymer battery might be the best prospect. LiPo cells have the highest current density for size of any battery I know of. A source I use has many different types, including LiPo, as well as chargers.
http://www.all-battery.com/

One of their current offerings is a 3 V 900 MAH battery 16 MM in diameter X 34 MM long, which is smaller than a traditional flashlight battery. They have other, larger ones which have even higher MAH ratings.

Semi-Traditional alkaline cells can actually deliver a considerable amount of current for a short time. One of my friends used to build and fly large radio-controlled dirigibles, and he used non-rechargeable alkalines to power their motors, because they could deliver a huge amount of current as long as they lasted- much more power delivery than NiCd batteries, which were the only small rechargeables available at that time.

The lithium batteries tend to be considerably more expensive than other types, but several 3 volt ones wouldn't cost a fortune. Chances are that 3 volts would serve to strike and maintain an arc, especially if the electrodes were thin, such as graphite "leads" for draftsman's "clutch" pencils, or the even thinner ones for "propelling" (UK) or "mechanical" (USA) pencils. A small clockwork mechanism could serve to feed the electrodes to maintain a consistent gap, and a button on the side could temporarily cause them to bridge. A study of early arc lamp technology would show how this mechanism could work.

It's a very interesting idea, and realizing it would be quite a nice project.

[Offlogic]

And the UV it throw off would probably be hell on the vampire in the vicinity, to boot!

[SteamKit]

Neat on the batteries, I'll have to think on it quite a bit. Poke around for casing options and whatnot. As for the vampires...well, Anti-Vampire is a great plus!

[Prof. A. Morphous]

Battery pack in one hand, wired to flashlight assembly with clips for consumable lead in the other, and off we go.

http://www.metacafe.com/watch/726251/turn_a_pencil_into_a_light/

Basically shorting an inch long piece of pencil lead across a car's battery, giving one "3-4 minutes" of light per piece of pencil lead.

-Prof. A. Morphous 

[Offlogic]

Hey, that is very very interesting!
I'm going to have to try that out just for the "McGuyver" factor involved.

[J.Wilson Esq.]

That's a very clever idea! And very simple, compared to an arc light mechanism. I could see a full length of draftsman's lead being fed through a snug metal bushing at the center opening of a parabolic reflector, contacting a metal cup at the focus point of the reflector. The reflector bushing and the cup would be the two isolated sides of the electrical circuit. The graphite lead would glow exactly as seen in the video, and the parabolic reflector would provide a directional beam of light. Since the lead and its propelling device would need to run through the axis of the, probably tubular, housing behind the reflector, the batteries could be incorporated into a pistol grip beneath it. A trigger could rotate a toothed gear engaging the graphite rod, pushing the lead forward until it engaged the forward cup, which would turn the circuit on. When the graphite electrode burned out, the trigger would be pulled again, starting the process over. I say, that's a crude but extremely elegant lighting device!

[SteamKit]

Neat!