Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!snorkelwacker!spdcc!merk!alliant!linus!eachus From: eachus@aries.mitre.org (Robert I. Eachus) Newsgroups: sci.electronics Subject: Re: Xenon flasher Message-ID: Date: 19 Jan 90 22:58:22 GMT References: <10224@microsoft.UUCP> <1990Jan15.214459.6707@waikato.ac.nz> <1059@khijol.UUCP> Sender: news@linus.UUCP Organization: The Mitre Corporation, Bedford, MA Lines: 47 In-reply-to: erc@khijol.UUCP's message of 18 Jan 90 04:09:21 GMT As long as we are on the subject... Xenon/Argon/Neon tubes when "properly" driven can do some amazing things. The good ones are almost indestructable. (They do evenutally fail by producing Xenon TriOxide (XeO3) which eats away the electrodes but that takes hundreds of hours run literally red hot. (If the bulb only glows red for about ten seconds after use, you are not overstressing it.) One project I worked on took a standard GE flashlamp designed for commercial photographers (rated at 7 watts average max.) and ran it with a 15KHz pulsed DC power supply at 2 kilowatts. Much better (and cheaper) than photofloods for high-intensity TV studio work. (Now mostly quartz halogen.) The largest flash lamp I ever put together was around 20 Kjoules (yes I've seen bigger, but this was my personal record. The capacitor bank was about four feet square -- Maxwell mylar capacitors 100 microfarad at 4 Kilovolts each. The pulse from this beast was not particularly sharp (1/2 intensity width about 1/2 millisecond) but boy did it light the room. When we fired it we would (already wearing protective glasses) turn and face away with our eyes closed. You would still get after-images. At eight feet the light was about 1000 times noon tropical sunlight. One time the wire to the trigger circut came loose. Reattaching it was not an option. Sneezing in the wrong direction was not recommended... (Remember there was 5KV across the bulb, and anything could cause it to go off, especially removing the voltage.) We figured how long it would take for the bleed resistor to get the voltage down to safe levels (below 2KV), locked the lab, padlocked the lab, put up a big sign "Do not enter before Tuesday," and caught up on paperwork. This testing resulted in a proposed "lighting system" which would consist of a motor generator pair, and a triggering circut. Once the tube fired it would effectively short the generator and bring it to a stop. The idea was to speed up the production of photolithographic plates (from exposures measured in minutes to fractions of a second). Loooking at the issues with the then new OSHA convinced us that the product could never be marketed. (Note that existing equipment was just as capable of blinding people if misused, but that this was "something new.") -- Robert I. Eachus with STANDARD_DISCLAIMER; use STANDARD_DISCLAIMER; function MESSAGE (TEXT: in CLEVER_IDEAS) return BETTER_IDEAS is...