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

Did some experimenting...

I have now etched away the copper of both welding rods, which nicely
saturated my etchant too...

1 rod is 8mm ∗ 22cm i think which is 55 square cm.
i connected both rods together to get ~~100 square centimeters.


for the other electrode i used a copper wire, diameter about 4mm and
length 10cm.
which is 12,5cm square.

i can only prevent chlorine gas by currents well below 0,5A (you know it
is hard to tell when
there is really no gas).

- that would be 5mA / square cm at the carbon then.

However i think the area of the copper wire is too big, i can not get
hydrogen at all, even
if there is severe chlorine. so i assumed it is too big and now i use a
1.5mm^2 wire immersed
only 2 centimeters. now i get hydrogen before i get chlorine.
I have it running at 150mA right now, and will see if it works.

The copper plates like a sponge, and it is kind of hard to get it out
without
shaking it all off again (and loosing it in the etchant).
It is funny how the copper grows. I suspect the area hugely increases when
the first
copper is deposited and the current density is wrong again.

I must say right now it is not looking very well. the etchant is much
darker than it should be and
all the experiments have not yet managed to regenerate it at all, I have
only managed to produce
chlorine.



I have also another question about chlorine, what are those tablets made
of for the swimming pool?
They say they are chlorine tablets but i am not sure. (thought pure
chlorine only comes in gas form).
I wonder if one could use them to regenerate the bath, what i notice when
i have too high a current
is that the chlorine gas produced clearly regenerates the etchant in the
surroundings of the carbon electrodes
as it turns a lighter color.


I will try to optimize the process further but if it does not improove i
will just stick with H2O2....

ST