Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

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