Hi Nuno T,
Thanks for the info on ballasts and tube Wattage.
I have often wondered whether they need to be matched.
Cheers,
John
From: Nuno T.
Sent: Wednesday, August 01, 2012 9:54 PM
To:
Homebrew_PCBs@yahoogroups.com Subject: RE: [Homebrew_PCBs] PCB light box - hf ballast / tube wattage
Hi John,
Don't have much experience with different exposure lamps to say which one is
better, but can give you some solid info on the HF ballasts vs tube wattage:
The power supplied by a HF electronic ballast must match the tube power
rating. There's a small allowable margin, but less than specified and the
lamp either won't light up or will light very dimly and flickering a lot. To
much and it will either blow it's filaments or will have a very short life.
Using an under rated ballast has no destructive effect that I know of, only
the lamp won't give it's full rated light level, if any.
HF electronic ballasts don't allow any type of parallel/series connections
has it happens with magnetic ballasts for 20W/18W type. There's some models
that can run several tubes from the same unit, but they have different
connectors for each lamp.
eBay has some cheap, and good enough models. Search like: "electronic
ballast 18W T8" or "ballast 2x14W T5" (there's no magnetic ballasts for T5
lamps, so no need to specify that in the search) Clalight seems to be the
best brand for price/performance ratio.
Nuno T.
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com
> [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of v321uk
> Sent: quarta-feira, 1 de Agosto de 2012 7:51
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] PCB light box - hf ballast / tube wattage
>
> When buying an HF ballast and fluorescent tube does the
> ballast wattage have to match the tube wattage?
>
> Is it allowable to use an hf ballast of higher wattage that
> that of the tube e.g. hf ballast 40W tube 12W ?
>
> Can you parallel tubes to an hf ballast intended for a single
> tube so long as ballast wattage is sufficient ?
>
> I am building a uv-a light box for sensitised PCB exposure
> and am not sure how many tubes to use.
> I am thinking get a higher wattage than needed hf ballast and
> say two 8 or 12W tubes so if there is insufficient light I
> could get one or two more tubes and parallel them.
>
> I usually use the sun for exposure but there has not been
> much of it here over the last few weeks and I need to make a PCB.
>
> Thanks
> John G3UGY
>
>
>
>
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