Homebrew PCBs

> > Me wrote:
> >The kalex box has light and dark patches. 

> Tubes are probably spaced too far apart.

My guess too.
 
> I started with this;
> http://www.pbase.com/eldata/image/52324065
> Then went to this to ensure that would never
> be a problem;
> http://www.pbase.com/eldata/image/52321530

Now that would have to be pretty even
illumination
 
> I'm not a fan of UV tubes as you can see.
> In fact the only UV tube here is in a 28
> year old EPROM eraser.

AFAIK there are 3 common types of UV tube.

The generic part numbers for these start
GT, BL and BB.  That is for

GT - Germicidal  = Nasty UV
BL - Black light = Bug zappers
BB - Black blue  = Disco lights

The two second sort (BL and BB) are abouts
the peak sensitivity of UV resist (at least
kinsten brand)

With some playing I did with them the
exposure times with normal white fluros
was significantly longer.  Theory I have
read says that a shorter exposure leads
to better line deffinition.  This may be
bunk - I don't know.  The white tubes
doubling as a light box is a good idea
if you do go that way.

I woudl imagine the number of tubes
Derek has would lead to pretty short
exposures anyways.

BTW - the GT tubes are no good for PCB
exposure either.  They are too short a
wavelength. They are only good for
EPROMS, killing bacteria, making ozone
and going blind.

BL and BB tubes can obviously be looked
at with no ill effects apart from those
you would get from drinking to much while
sitting on the patio or at the disco.