I too have had one of these "let go". I have a lamp near my reading chair that used a 3 way Fluorescent lamp. While reading one day I began to hear a hissing sound followed by a loud bang (like a fire cracker) and "lights out". Upon examination the class envelope of the tube near the base had overheated to the point of flowing and eventually bursting. Not a great feeling - and again if I had not been home at the time to pull the plug????? Do these things have a safety issue?
Rodger, N4NRW ---- Original message ---- >Date: Sat, 04 Oct 2008 20:39:55 -0800 >From: Jim Wiley <[EMAIL PROTECTED]> >Subject: Re: [Elecraft] smoke test >To: [EMAIL PROTECTED] >Cc: [email protected] > >Ralph - > > >Many - not all - fluorescent lamps (I am assuming you are talking a >CFL , or Compact Fluorescent Lamp) have a small resistor used as a fuse >for the ballast. The ballast is in the base which supports the >discharge tube (the fluorescent portion). The ballast develops the >voltages needed to initially fire the tube (when cold) and limit the >current once the arc is initiated. It consists of several capacitors >and resistors as well as a few semiconductors. As the tube ages, the >current draw increases. At some point, it becomes too much, and the >ballast fails. To prevent a really catastrophic failure, a small >resistor (typically a 1/8 or 1/4 watt unit) is used as a fuse. Overload >destroys the resistor, cutting off the current. Why a resistor? They >are much less expensive than fuses, particularly at low current >ratings! The light from a CFL comes from a mercury-vapor arc inside the >tube, which emits large amounts of ultraviolet light. The phosphor on >the inside of the tube converts the ultraviolet energy into visible light. > > >- Jim, KL7CC > > > >Ralph Tyrrell wrote: >> As I sit at my computer the radio desk is to my back. I heard a burst of >> static behind me. That was odd since no radios were on. The only thing on >> at the radio desk was the desk lamp and a power supply that keeps the >> batteries charged. Both are plugged into a strip that switches power to them. >> >> I went over to the radio desk and looked at my equipment, both off. Still >> puzzled I turned on the 2m rig, all normal. Then I turned on the K3. All >> normal. I turned them off again. The K1 sits by, not connected to anything >> at this time. >> >> Still puzzled I sat there wondering if something had happened to my battery >> bank or one of the batteries. I have three 26AH batteries in parallel. Each >> battery is fused before to goes to a fused buss. >> >> Then my nose began to notice the smell we all dread. Something electrical >> was over heated. Still I did not noticed a symptom I should have noticed >> earlier, the desk lamp was off. I touched the top of the lamp and it was >> very hot. The bulb, a 13 Watt Florissant had failed. The ceramic base was >> too hot to touch. >> >> How often do Florissant bulbs fail this way? >> >> I had the feeling that if I were not there a fire may have started. >> >> 73, Ty, W1TF, K3 #696, K1 #1423 >> >> >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [email protected] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> >> >_______________________________________________ >Elecraft mailing list >Post to: [email protected] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
