Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "zip1zip1zip1" <tom@...> wrote:
>
>...
> 
> BestHongKong
> http://stores.ebay.com/BestHongKong_W0QQtrksidZp1638.m118.l1247
> 
> List three different LED's
> x561 390-395nm   100/ USD $8.75 ship $8.95
> x562 395-400nm   100/ USD $7.75 ship $8.95
> x563 400-410nm   100/ USD $9.95 ship $8.95
>
> 
> Tom
>
I bought about 100 of each of these grades from BestHongKong and they
seem entirely satisfactory.  I was looking at the absorption maxima
for organic materials (fish-glue gelatin and some of the
polysaccharide gums) and found that the 390-395 range looked best, but
all seem to work.  I ended up buying some UV strips with 3 LEDS
mounted on an aluminum carrier that are set up for 12v.  They seem to
produce more output than I would guess.  I have more problem with
overexposure than with underexposure.

I mounted the strips on a 1 foot chunk of heavy aluminum heat sink
(because that is what I had handy), wired about 9 of the 3 LED strips
in parallel.  I hooked the whole works to a gel cell battery (too lazy
to build an adequate power supply) and an old darkroom timer.  I put
the leds in an old, gutted HP scanjet which makes a great contact printer.

Anyway, BestHongCong has been a good source for LEDS.  I just wish
that they had more chip-type LEDs and some shorter wavelengths (365 -
385 would be helpful).  And good, cheap, stable single mode UV Laser
diodes.  I want to try direct-draw on photosensitive material with an
inkjet mechanism with the jet heads replaced with a laser diode.

-- Dave