Homebrew PCBs

----- Original Message ----- 
From: "John Craddock" <John.Craddock@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 25, 2006 8:13 AM
Subject: RE: [Homebrew_PCBs] UV Light Sources


>
>
>> -----Original Message-----
>> From: Leon Heller [mailto:leon.heller@...]
>> Sent: 25 September 2006 16:27
>> To: Homebrew_PCBs@yahoogroups.com
>> Subject: Re: [Homebrew_PCBs] UV Light Sources
>> >operating. Can any one confirm that this is comparable or
>> better than the
>> >black-light fluorescent approach?
>>
>> It's a lot better (much shorter expoosure), but needs to be a
>> long way from
>> the PCB/artwork for good collimation (something like 1 m,
>> IIRC). I've got
>> some similar sodium lamps that can have the outer envelope
>> removed. The
>> ballasts can be difficult to find. For accurate exposure I
>> think you need
>> some sort of shutter arrangement as they take some time to warm up.
>>
>> Leon
> Thanks Leon
> For the collimation I was going to use a parabolic reflector. With a 16" 
> (400mm) dia., reflector it would seem to be feasible to have a working 
> exposure area of 12" to 18" (300 to 400mm) Instead of a shutter I was 
> thinking of using a slide-in frame holder. In OZ we can get 250 watt self 
> ballasting globes the run off our 240 volt mains supply. This set-up would 
> be far less expensive than say 4 or 5 fluro tubes plus their associated 
> ballasts, starters etc (at least in the antipodes).

I was going to remove the envelope from one of my sodium lamps, but the cat 
knocked it off the bench onto the floor and did it for me. 8-) I got some 
ceramic bulb holders without any problems, I really must get a ballast and 
try it out. I got the bulbs cheap on Ebay; I should have got one of the 
units you mention, it would have been less trouble.

Leon