Homebrew PCBs

grantfair2001 wrote:
> Thanks for the additional information. Did you use the pipe layout
> which Think and Tinker recommends, like a U shape, with the PCB in the
> middle between the "legs" (if that makes any sense at all)?

Something like that. but I think the porous hose works better. 
Aquarium air stones are good too.

> 
> The air tubing I have on hand is Tygon F-4040 A. I know little about
> it except it's cheap at my local surplus store and I believe it is
> fairly non-reactive to most chemicals. (Please correct me if I am wrong.)
> 

 From the chemical chart, Tygon seems ok in most acids. I know 
that solid nylon just crumbles apart after a week in 20%(w/w) 
sulfuric acid. The only problem with the soft clear PVC tubing is 
it tends to become tacky on the surface after a few weeks. It 
doesn't seem to penetrate very far.


> For air I thought I would try a portable tire inflator from Harbor
> Freight, or perhaps an old Gast vacuum pump I've had kicking around
> for years, if I can figure out how to use it as a compressor. Failing
> that a buddy has offered an aquarium pump but my etch tank is a 34
> quart capacity Coleman chest cooler, so I am unsure it will have the
> needed air volume.

Try it and see. sewerage treatment aeration pumps are perfect for 
the job. I should look on the secondhand market. Last time I 
checked a new Nitto Kohki 80L/min pump was about $500.
A 'large' aquarium pump might be 2L/min

> 
> I have also found some cheap 1/2 mL pipettes (C$ .25) and a surplus
> 100 ml cylinder specified to +/- 1 ml (C$ 7), which seems like it
> would be fine for measuring for titration, since the article suggests
> results within  +/- 10% are fine for adjusting the acid level. I am
> hoping a student burette will do the trick since, so far the best
> proice for a legit version will set me back $140 Can. 
> 
CA$140 sounds expensive. Here in Australia a lab place near me 
sells "Brand" 50ml (class B) burettes for AU$70. Still, expensive 
so you might want to have a better look around. Pipettes are not 
terribly expensive, around AU$4 to $6. Order as many free 
catalogs as you can.

> Also- anyone know of a reasonably priced source of bromophenol blue?
> So far the best I have seen is C$ 65.00 for 5 grams of ACS grade. That
> seems like an awful high price, and if a lab grade is available I
> assume that would work ok.

Yep, that sounds about right. I think the best thing for you to 
do is post that question on sci.chem news group explaining you 
are titrating  HCl in cupric chloride. approx. strengths 1 Molar 
and can accept few percent error. I am using methyl orange with 
good success.