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Thread ID: 24858	2002-09-20 09:16:00	Computer Mods	roofus (483)	Press F1

Post ID	Timestamp	Content	User
81424	2002-09-21 01:03:00	Sorry, but flouros are cold cathode, hot cathode is incandescent.	godfather (25)
81425	2002-09-21 01:16:00	Really? :O Wow, you learn something new every day!	antmannz (28)
81426	2002-09-21 01:21:00	Someone at the link JM gave has used the $20 warehouse lights in their case - look at the forum on case modding for about two or three weeks ago. G P	Graham Petrie (449)
81427	2002-09-21 02:15:00	Yeah God, I'm with you there. You certainly would get a bang if the lamp was supplied directly with 230 volts without current limiting by ballast or other means. However, what I was saying was that such a lamp could be modified to run off 230 volts but not directly, that's what the modifications are all about. Of course, the lamp would be unlikely to strike without the necessary HV pulse, but then who knows.?:| I have a twin flourescent fitting in my garage (one of four) that gives full light output the instant the switch is pressed (just like an incandescent bulb) while the other three fittings all go through the normal starter routine to get them to strike. The instant-on one hasn't even had time for the filaments to warm up! I've never worked out why or how this is happening, but what with you being omniscient and all that, this is a great time to ask and see if you can shed any light on this somewhat puzzling event. Of course I could just pull the starters out and see what happens but it's one of those real old jobbies where you have to take the tubes out and remove the cover to get access (I bought them as a surplus job lot when the Ark was being broken up) and I'm too lazy to climb up and do that. I rewired all four fittings with new ballasts and PF caps several years ago to get rid on the leaky pitch filled ballasts (which I consider to be a fire hazard) and the PCB filled caps. Maybe I wired that one wrong but I can't see how that could produce an instantaneous strike. I always thought it was divine intervention, disillusion me if you must. Cheers Billy 8-{) :D :D	Billy T (70)
81428	2002-09-21 02:25:00	Not quite right, godfather . . . normal 230V fluorescents use a starter to connect the hotcathodes (filaments) in series with the ballast (choke) . When the starter opens, the reactive voltage kick, and the electrons available from the filaments start the arc in the tube, current limited by the ballast . There are different installations which do away with the starters and run on a higher voltage for cold starting . Low voltage ("12V") fluorescents use the DC in an inverter, producing high voltage, current limited AC, to run the tube as a cold cathode lamp . Some of the car tubes are called "neon" tubes . . . they could well be (or other rare gases for different colours) ;fluorescents basically produce UV from the mercury vapour arc, and colours are determined by the phosphors on the inside of the glass . A neon tube just needs high voltage (the street signs use about 10-15 kV, from a current limited transformer) which can come from an inverter . Have a look at the current issue of Silicon Chip magazine . They've got a construction project for about 36W tubes .	Graham L (2)
81429	2002-09-21 04:54:00	Yes Graham, I was only talking about the 12 v ones, I am fully aware if the hot cathode in 230v fl. (probably rates them as luke warm cathode lamps) I have studied the CFL (energy efficient lamps) systems quite extensively, have even studied the manufacturing process, including phosphor types. As a point of interest, if you get a 3-loop CFL lamp and disect it, you will find only 2 of the loops have electrodes, the 3rd one lights with radiated energy from the others.	godfather (25)
81430	2002-09-21 05:33:00	Wouldn't there be a risk of messing up the nice clean power the brains of a computer needs if you whack a crude inverter into it that is designed simply to power a flouro lamp as cheaply as possible? I would imagine that it would be the natiest little squarewave spikemaking device. This wouldn't matter in a car, it's allready got an engine to mess up the cleanness of the power, and anything needing clean power usually has some kind of filter anyway.. but in a computer?	Chris Wilson (431)
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