EPROM Erasers?

Jeff Walther wrote: projectionist, carbon arcs were very impressive. Although some stage spotlights used AC arcs, all of the arcs used in projectors were DC- powered. Usually by a sizeable MG set (40 HP motor), although the smaller houses could get by with 3-phase selenium rectifier setups. Wall-mounted ballast coils and water-cooled electrode holders. The anode (IIRC) was about 1/2" in diameter and perhaps 18" in length, while the cathode was much smaller and usually copper-plated. (Most of the light was radiated from the anode face, so the cathod actually met the anode at about a 30 degree angle so as not to obscure it). An anode would last about 2 reels (40 minutes, give or take). Some of the more clever "cans" used an aperture and phototube assembly to track the face of the anode and adjust the (motorized) feed speed accordingly. Because the can was forced-air ventilated, the arc actually appeared as an upward-pointing flame (I'm sure that was just the incandescent carbon vapor glowing). Observation of the arc was always done by looking at the image projected onto a surface by a pinhole opening. There were "black glass" observation ports, but you were warned not look through them for any amount of time. If you had a watch with a luminescent dial, you could hold it near the black glass window and notice how brightly the face glowed. That probably was the UV. One probably could have erased a whole bunch of EPROMs by putting them inside the can with the arc.... :) Cheers, Chuck