Sorry Guys, I was on holiday while this thread was active !
If anyone is worried about the beam pattern, it is easy enough to make
standard 5mm LEDs wider angle..
When assembled, just work the board LEDs down, on a sheet of 600 wet
and dry, in a circular motion..
do this until the tops of the LEDs are flat...
then do the same on a sheet of card, using 'T' cut or other paint
refinishing paste..
it works a treat.. you will get a good 100 degrees or so, problem
solved...
Chris
--- In
Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@...>
wrote:
>
> Markus Zingg wrote:
> >
> >
> > Adam,
> >
> > I do have a 20mm grid spacing, and I'm so far satisfied. Even
though it
> > never formed a problem of any kind, one can SEE the grid on the
> > resulting exposed laminate. It's seen like kind of darker and lighter
> > circular shaped areas on the exposed resist. Again, developping the
> > result always worked excellent with no irritations in the result
whatsoever.
>
> That's good to hear it works despite the visible pattern. What is your
> space between the LED and PCB ? I guess the larger the distance the
> greater the light overlap of adjacent LED's and possibly better
uniformity.
>
> > At the very surprisingly low prices of these LEDs, I would consider
> > using an even more narrow grid. My box (kingbright leds, with what I
> > understand only 160mcd typical) result in a one minute exposure time.
>
> The BestHongKong ebay seller Tom pointed out had the better specs
> (tighter spectrum tolerance, polar plot). Interestingly , some LEDs are
> rated in mcd while others rated in mW. BestHongKong 5mm UV LED's are
all
> 11mW 20 degree. I think I'll get these. But might also get $11 ones
from
> Winsome House Store just for fun.
>
> >.... I would spend the time to build a complete exposure unit to make
> > sure they work.
>
> For sure. Some preliminary testing will soon give me estimate of
> exposure times vs grid spacing and test non-uniformity.
>
> I'll be sure to let others know how it goes.
>
> Adam Seychell
>