Homebrew PCBs

Think & Tinker has some suggestions regarding bubblers at 
http://www.thinktink.com/stack/volumes/voliii/equipment/bubltank/bublt
ank.htm .

Lyman

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:

Hi everyone.

I decided i do need some sort of agitation for my etcher.
i tried moving the board, it works well but tends to shake to board 
loose of the holder. The etching takes too long, and it is very 
uneven because the spent etchant sinks down.

So i went to a aquarium shop for a air pump. got one for 10eur, took 
it apart and found the pumping part is made entirely of rubber
and plastic (only one M3 screw needs relacement with nylon or a 
protective silicone coat). This means for me i can scoop up the air 
from under the cover of the etch tank, releasing no corrosive
mist into the room, or at least much less.

I got a bubble-stone with it, but it is just a small (2cm) ceramic 
ball, no good for even distribution of bubbles. They don't have other 
bubbling stones, i believe i remember reading about "fritted glass" 
or something here? What about making holes in a hose? would that 
cause too-big bubbles, and too few?

Another thing is, do you think those air pups can pump liquids?
alternatively to pumping air i might just pump the etchant around. I 
will test that with water. Other pumps (centrifugal for aquarium 
filters)have a magnet exposed to the liquid, and a metal shaft 
(expensive ones have a ceramic shaft, or so they say). Would the 
magnet be attacked by etchant? it is a hard "black" type,
not a neodymium magnet. Maybe the magnet could be painted or 
something...

While we are at pumps, i learned something interesting: for CO2 feed
systems the aquarium guys use reactors. that is a cylinder where the 
water is pumped downwards, while the co2 gas rises against the 
current. they place obstacles into this cylinder too. If it is 
adjusted correct almost no CO2 reaches the top, all is solved in
the water. this might be an effective setup for air-regenerating CuCl.

thanks for any hints about that bubbler stuff (but suppliers in the 
US are not of much use).

ST