[sdiy] PCB exposure

[Michael Buchstaller]

For years, i have been using a 250W Photo bulb that you can
buy everywhere. (in Germany, Conrad has them, and most eletronics
shops do, too.)

But recently i changed to one of my 1000W video lamps. Exactly the
same results. No need for a special UV lamp.


BTW: i n the past i have had problems with getting consistent results from
this, mainly because i had to put away the lamp and then forgot the exact
time and distance from lamp to PCB, and not to forget aging of the lamp.

To cure this, i have found out that i could just put a gray card there instead
of the PCB and measure the brightness with a light meter. For me, when i
set the "film" sensitivity to 25 ASA, time to 1/60 sec, then i adjust the lamp distance
to get a brightness of 11EV. Then i can put the PCB in the light for 6 minutes,
and everything is fine.
Bu doung this metering (and writing up the required values) i can now easiy
switch between different lamps and get the same results.


-Michael Buchstaller