PSN-L Email List Message

Subject: schematics to circuit boards
From: S-T Morrissey sean@...........
Date: Sat, 17 Jun 2000 18:49:27 -0500 (CDT)


Regarding your suggestions about amateur electronics by PSN members:
It is in line with the recent discussions about the widely varied
capabilities of the members. As Cap has pointed out, not everyone
can be a Jack of all trades ( and master of none, as it goes).
So simply posting a schematic may be enigmatic to many. But, as
has been noted, for some, purchasing a plug-and-play electronics usually
leads to some certainty of success, but for many is is not as rewarding
as having a part in the assembly of the electronics. I doubt if
anyone has the time to write a "Heathkit" type document ("put wire B
into hole C(s3)" ), but maybe, some of us could take the time to document 
layouts for the circuits on perforated/foil pads circuit boards,
especially when we have already done such a layout.  Or better yet,
if the PCB has been previously printed, find someone to manage 
distribution of the blank board.

An important point is that it doesn't have to be all that complicated.
Double sides, ground plane, plated holes, etc, are not really needed until
you get into RF work. I have never used them because all I could do
in the darkroom for prototypes is single sided boards. The seismic
amp I show on my web site is just that. I also made a compact perf-board
version of it to fit into a hydrophone case. All the boards for the VBB
fedback seis and the NSF tiltmeter are single sided.

And for one to four prototypes, I use the perforated boards with the
rows of 3-hole pads and linear foil strips. These work great, and I
use a layout pattern on the PC here to work out parts and connections
before I start soldering. Currently the highly regulated DC supply for
the VBB vertical seis is done this way. I cut a Vector #3677 board
(with edge connector; from Newark (every PSN electronics amateur should
have their catalogue; they take MC, Visa, etc) for about $24)
lengthwise (with the office paper cutter) to make two. This technique
could be done for any circuit and then many PSNrs could get the 
satisfaction of rolling their own and get something predictably reliable.
I wouldn't use the push-in type breadboards for more than evaluation,
and I wouldn't trust the spring-clip devices more than an hour, which
is about how long it takes to teach someone to solder correctly
(Heathkit had a great instruction sheet on this).

Of course, plan B might to be to show how easy it is to work from a
schematic, possibly using the european notation for components (like
boxes for resistors). One needn't know WHY the various connections 
are made, and simply replicate them in assembling components. I have
had determined students just plug all the components in a row down the
center of a vector board (using sockets for ICs), then install each 
connection with a jumper wire as they are marked off on the schematic 
with a highlighter. To their surprise, they generally worked, and at
seismic frequencies the spread-out layout and rats-nest of wires posed
no noise or stability problems.


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Larry Cochrane <cochrane@..............>