PCB vs perfboard construction economics (was Re: "New" PDP-8)

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Mon Apr 1 16:35:39 2002

--- Ben Franchuk <bfranchuk_at_jetnet.ab.ca> wrote:
> ...The board will be about 8" x 7" and $175 canadian for two
> prototype boards. Wire wrap sockets/wire/protoboard would cost me $100...

While I can recommend a real PCB if the setup costs and the per-sq-in
costs are not killing you (price an Omnibus or Unibus-sized 4-layer board,
complete with gold fingers!), personally, my WW overhead isn't terrible:
I rescued all the prototype hardware from my former employer when they
went bust - I probably have three lifetimes worth of WW sockets. When
I do a project, the only part I have to spend money on is the wire.

My last project is a good case-study for expense vs. time. I wanted to
replicate a scoreboard from a Dragon's Lair/Space Ace. I tried to find
one on ePay, but they only come up occasionally (every couple of months).
I decided to build one. I started with a couple of digital pictures,
a parts list and a schematic. Since the board was approx 6"x9", it
would have been somewhat expensive for a commercially-made PCB. There
are still plenty of surplus units out there that sell used for under $50
when they are available, so it would be cheaper to wait for a sale than
to have a professional PCB created unless the new PCB added value somehow.

I had the blue perfboard (from when the MicroCenter got rid of all of their
prototyping hardware at 80% off list!), the wire and the discrete
components. I had to purchase the LEDs ($0.65 each) and the driver chips
(a few bucks each). Total out-of-pocket expense was <$25. I probably
pulled about $15-$20-worth of supplies out of my parts bins.

Construction took place over several evenings, watching the sci-fi channel,
tacking down point-to-point connections (didn't have the vertical
clearance for socketing the LEDs). I'm pleased that it worked the first
time! - pictures at http://penguincentral.com/retrocomputing/retrogaming/
under the "LED Scoreboard" link. Mostly, it's pictures of the glow of
the LEDs, but there's one out-of-focus, flash-burned picture of the
perfboard and yellow wire in there (the Apple QT150 has about a 24" min
focal distance without the strap-on lens).

The upshot was that if this were being done for anyone but me personally,
it would have been an economic disaster. Nobody would have paid me a
reasonable amount for that much work - it would have been much cheaper
to go to an arcade service company and *buy* a used scoreboard than spend
10+ hours wiring up a board. It would have been much cheaper than that
to wait out the next wave of offerings on eBay (which I accidentally did -
the project took so long to complete that I _did_ pick a real one up for
around $30, after I was 95% finished with my replica. The good news is
that it made a nice functional benchmark to prove that mine worked).

So I chose to trade my time for semi-instant gratification. I would
have loved to have done a PCB, but I chose not to spend the time with
layout tape and a blank board, and I chose not to pay to register a
demo-ware layout package so I could make a 6"x9" board. If I were to
make the new PDP-8 design that kicked off this whole thread, I'm not
sure if I'd get professional boards (~$200/set, in small quantities,
according to the designer, for a couple of 4-layer boards) or I'd
point-to-point it. In terms of $$$/hour, even $200 for a board set
is cheap. In terms of a discretionary hobby, $200 is a lot to divert
from other projects when I already _have_ a working PDP-8. With that
kind of money, I could start trolling for a Qbus SCSI controller!

Back to the initial topic, though, I'd love to get a good buy on a dozen or
so spools of kynar-coated wire. I'd prefer an assortment of colors, but
I'd take it in whatever I could get - yellow, red, white...

Anyone have a lead on any surplus places that have it for a few bucks
a spool?


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Received on Mon Apr 01 2002 - 16:35:39 BST

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