Re: gEDA-user: [OT] Fluorescent tube help

2010-08-13 Thread Mike Bushroe
I do not know much about fluorescent tube ballasts, but I can give some general guesses. 1) Wattage is going to relate to total amount of heat dissipation that the ballast can handle. 2) Tube length (each in parallel or both in series) relates to the voltage needed to first strike

Re: gEDA-user: [OT] Fluorescent tube help

2010-08-13 Thread Chris Smith
David Smith wrote: > > From my limited knowledge of how fluorescent tubes work... > > During the start phase, the starter short-circuits the tube allowing > current to flow through the starter and the heating filaments at the > ends of the tube. If you put two tubes in series and the starter is

Re: gEDA-user: [OT] Fluorescent tube help

2010-08-13 Thread Chris Smith
John Griessen wrote: > > If you can get the same bulbs and it's not expensive, run them and maybe > they burn out > and who cares, as long as you have some good insulation protection from > the HV. I guess so, it's just, well... I'd like to _know_. :) > You could try DJ's UV LED methods and skip

Re: gEDA-user: [OT] Fluorescent tube help

2010-08-13 Thread David Smith
Chris Smith wrote: > I recently purchased an old, second-hand UV exposure box to try making > PCBs at home. One of the tubes has started to fail and in replacing > them I have noticed something odd: the box takes two 12" 8W T5 tubes, > but has only a single 13W switch-start ballast. I assumed tha

Re: gEDA-user: [OT] Fluorescent tube help

2010-08-12 Thread John Coppens
On Thu, 12 Aug 2010 09:53:43 -0500 John Griessen wrote: > Or shop for a second hand UV tanning lamp? Another solution might be looking at the circuits that excite the tubes with high frequency. With a simple oscillator, you can use the tubes without the filament, and if they still have gas, they

Re: gEDA-user: [OT] Fluorescent tube help

2010-08-12 Thread John Griessen
Chris Smith wrote: I assumed that a previous owner uprated the tubes without changing the ballast, but in looking for a replacement I have become stuck. I can find plenty of general information on how fluorescent tubes work, but no specific advice on ballast selection. 2. two tubes can be w

gEDA-user: [OT] Fluorescent tube help

2010-08-12 Thread Chris Smith
Hi all, Sorry for the OT post, I've googled this to death without finding an answer and was hoping someone here might know. I recently purchased an old, second-hand UV exposure box to try making PCBs at home. One of the tubes has started to fail and in replacing them I have noticed something odd