Alt-BEAM Archive
Message #06754
To: beam@sgiblab.sgi.com
From: "Mike Kulesza" mikekulesza@hotmail.com
Date: Fri, 15 Oct 1999 22:31:35 GMT
Subject: [alt-beam] Re: PCB etching
Does anybody recommend Radio Shack PCB kits?
______________________________________________________
6755 Fri, 15 Oct 1999 23:30:09 GMT [alt-beam] Re: F?!?! beam@sgiblab.sgi.com "Mike Kulesza"
According to an Active Electronics catalogue, F stands for Fast TTL.
>From: Iv Clarence Harper
>Reply-To: beam@sgiblab.sgi.com
>To: beam@sgiblab.sgi.com
>Subject: F?!?!
>Date: Mon, 11 Oct 1999 16:59:54 -0700 (PDT)
>
>I was going through some newly acquisition junk-box material when I came
>across a bunch of boards that had been manufactured by digital. While
>peruse them for salvage, I can across two banks of 20pin ICs marked as
>74F240's. Does anyone know what the F stands for?
>
>I found the datasheet for it at
>http://www.mot-sps.com/books/br1514a/pdf/mc74f240rev5.arch.pdf
>but I'm having difficulty interpretting it.
>
>Would these be good for solarized applications, battery only, or should I
>not even waste my time trying to pull them off the board?
>
>thanks
>-Clarence
>~~~~~
>Never before has such silliness passed as serious business
>~~~~~
>
>
>
>
______________________________________________________
6756 Fri, 15 Oct 1999 20:19:16 -0400 [alt-beam] Re: PCB etching beam@sgiblab.sgi.com Richard Weait At 10:31 PM 10/15/99 +0000, you wrote:
>Does anybody recommend Radio Shack PCB kits?
. . . is that silence that I hear? . . .
Use ammonium persulphate for etching, rather than ferric chloride.
The crystals are easier to store, you can 'see' the reaction, and
judge when it is complete.
Read the label and follow the safety instructions.
Cheers,
Richard.
6757 Saturday, 16 October 1999 12:02 Re: PCB etching beam@sgiblab.sgi.com ; beam@sgiblab.sgi.com Robert Stein
>At 08:17 AM 10/15/99 -0500, John Leo Zimmer wrote:
>>-----BEGIN PGP SIGNED MESSAGE-----
>>
>>No one has mentioned using a laser printer or copier to make a
>>circuit board.
>>
>>I do not have a laser printer available here at home so I print my
>>circuit with my inkjet printer. (Must be mirror image of the desired
>>final result. Your software has to provide that.) Then carry it to
>>the office and "Xerox" it. (Printing double size at home and reducing
>>it increases the resolution and allows for some touchup or freehand
>>additions to the origional.) The toner is plastic fused to the paper
>>with heat. It can be fused to your clean copper with the right amount
>>of heat and pressure ... too much of either makes a blob, not enough
>>and it won't stick. Use Mom's iron :-)
>>
>>Then you throw the thing into water to soak off the paper. And you
>>have your circuit printed to the copper. Touch up with Sharpie Ultra
>>Fine point, or other resist. Etch as described elsewhere in this
>>thread.
>>
>>DigiKey, etc. will sell special paper for this purpose, but it is not
>>necessary. I've experimented papers. Try fingerpaint paper. You want
>>something that disolves easily (coated) and does not fuse excessively
>>with the toner. In my hands the whole process is very much an art,
>>rather than science. And trial and error pays off. The results are
>>much nicer than hand drawn. And once you have a circuit you like and
>>you've developed the right touch, turning out multiple copies is like
>>making cookies. Developing the resist is a lot like working in a
>>darkroom and watching your photo rise out of the blank paper. Great
>>fun.
>>
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>>Comment: JohnLeo Zimmer MD
>>
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>
>There is another process, but it takes another chemical, but you will get a
>higher quality printed board.
> You will need to get a kit that contains some photoresist solution
>or pretreated copper clad, developer and etchant. Make the masks as
>mentioned as above, but on transparencies (make sure it is a negative of
>the trace file you created.) The photoresist or pretreated copper clad IS
>light sensitive. Use an ordinary yellow bug light to work in. Sandwich
>the mask on top of the board. Expose it to the sun for approx 30
>sec. Develop it for about 1 - 2 min. Rinse, bake at 60 -80 C for approx
>10 min. Then etch as normal. You can also get tinning solution. It stinks,
>but does a great job of tinning all of the traces and pads.
>
> I know some of you might be wondering Why go through all of this
>trouble.....If you want a smaller circuit make it double sided. make too
>masks, with a crosshair off to the side and use a double sided copper
>clad. Line up the crosshairs of the mask, with the copperclad
>between. Then expose both sides of the copper clad. etc. etc
>
>It sounds like more work, but the results far outweigh and more
>inconvienence, but I don't think that it is any harder. I have made a few
>boards already from Ian. They turned out great.
>
>later,
>
>Robert Stein
>Applications Scientist
>Spectral Instruments, Inc.
>
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