Homebrew PCBs

I am going to be building my first UV exposure box here soon. As a rule I like to source as much as I can locally. For a UV source, I looked to Lowes. I found replacement bug Zapper bulbs (purple, 'u' shaped), or clear mercury vapor bulbs. Both were priced around 15 dollars. Which would be best? Considerations for ballast?

As a secondary I thought about getting UV leds since I wouldn't have to fuss with a ballast

Can I still use hydrochloric as my etchant?

Chris



--- In Homebrew_PCBs@yahoogroups.com, Russell Shaw <rjshaw@...> wrote:
>
> On 21/01/12 04:51, Jeff Heiss wrote:
> > Russell, where did you find the cylinder reflector?  Did you buy it,
> > scrounge it from something you took apart?
> 
> I derived the parabola formula then cut out a parabolic arc in two supporting 
> sheets of wood then bent some shiny 1mm aluminium sheet into it.
> 
> I just re-derived the formula and it seems correct from rough sketches:
> 
> x = 2.SinQ/(1 + CosQ)
> y = (d - f + (d + f).CosQ)/(1 + CosQ)
> 
> x: horizontal distance from center of parabola
> y: vertical distance below x-axis
> d: distance between x-axis and lowest part of parabola
>     (parabola is assumed to be below x-axis and d and f are positive numbers)
> f: distance between focal point and lowest part of parabola
> Q: angle of ray from vertical (ray comes from focal point)
> 
> Q = arTan(x/(d - f))
> 
> It was years ago and the formula does not look familiar (i must have had it in a 
> different form then).
> 
> I have the HPW125 globe lying horizontally in the focal line of this cylindrical 
> parabola.
>