Homebrew PCBs

Hi John,

I am responding to your message in: "Re: PCB light box - hf ballast /
tube wattage - 400W floodlight instead?", in which you wrote:

> Do you think a car quartz halogen headlamp would have sufficient UV
> output ? I have a new 12V dual filament 50W + 65W which I could
> parallel to give 115W.

> My PC is only 8cm  x  3cm.

I guess a quartz iodide (AKA quartz halogen) headlight lamp would work
OK with a distance suitable for small boards and with a few minutes for
exposure.  However it would depend greatly on the voltage you ran it
from.  The UV output of an incandescent filament goes up dramatically
with its temperature, so if you ran it from 11 volts and got little
action, and from 13 volts and got a much greater UV output, I wouldn't
be surprised.

With these currents and voltages I think it would be good to use thick
wires and measure the voltage at the lamp terminals.  I suggest running
it at 13.8 volts - which is a typical maximum voltage in a car.

Some kind of reflector, such as made from a nicely bent fragment of
aluminium pie dish would help.

As with the 400W quartz halogen floodlamp, I think heating of the board
might be a problem.  A fan blowing on the board should fix this.


> Alternatively, I have a new 12W T5 circular (11cm 41/2")  Fly Zapper
> tube.
>
> The sensitised PCB needs energy around 360nm.

I don't know what their output wavelengths are, but as far as I know
they are not in the 350 to 380nm near UV range.  Do you have a tube
number?  Googling it should turn up a spec sheet.


  - Robin          http://www.firstpr.com.au/pcb-diy/