Do you guys find that every or most projects you work on have 1 or more
special parts that are a *bitch* to get? I've made a few simple
circuits before and I'm wondering if this is how it's always going to
be if I keep making more projects. Why is it that fewer people are
building electronics gadgets? There used to be a couple of nice
electronic parts stores in the San Fernando Valley that are gone now.
Also I remember when Radio Shack had more parts and they also had kits
and electronics learning sets.
Where are you finding these projects? As I pointed out recently, I
think here, newcomers often come across old schematics but don't yet have
enough knowledge to realize that it's old. So they ask about where
to get tunnel diodes, or that PNP germanium transistor, and the real
reason they can't find those devices is because they've been pretty extinct
for decades. Even ICs usually have a finite life span, and what was
plentiful in 1975 may not be the case any longer.
On the other hand, older projects have the advantage that they tend to
use fairly generic parts. That's certainly the case with projects that
don't use ICs, and even after the more specialized ICs tended to come later.
I remember the first project I tried to build, back in April of 1971 when
I was 11. I knew nothing, but like so many I copied the parts list from
the magazine and went to the electronic store. They made some substitutes,
which I didn't have the knowledge to evaluate, and I had no choice but to
buy all those parts new and spend the money.
This was better summed up a few years later when someone at school said
"I don't want to make a mistake" when I lamented that he'd spent Big Bucks
on an HEP replacement line op-amp when he could have used a common 741; he
wanted to follow the parts list perfectly because he had no leeway if things
didn't work.
But ultimately that is an important thing. The more you understand, the
more you can comprehend what's going on in the project. Then you can
determine which parts must remain identical, and which parts can be
replaced with cheaper alternatives. Or, use the project as a framework
for a concept, and then build something similar.
ONe of the best things I learned early on was about making do with available
parts. Ironically, the first thing I got to work (as opposed to the two or
three first projects that I bought all new parts for) was something made
with an audio transformer I took out of a radio, and some transistors I took
off some surplus computer boards (computer as in mainframe, since it was
1972) and I guess the resistors and capacitors came out of the radio. By
that time, I'd soaked up that it was possible, and had gotten a handle on
enough to realize I could use just about any small signal transistor for
the application.
ANd of course, the longer you build things, the more "spare" parts you
have. THere will always be parts you need, but the basics, or reasonable
replacements, will always be at hand, because you've stripped down all
those VCRs you find in the garbage. (Ironically, I find it easier to
find basic parts in that form, since 35 years ago all you'd find in
the garbage was pretty much tube tv sets, with the components coated in
that fuzz, but nowadays there is so much electronic equipment that lots
of it is available as garbage or real cheap at garage sales.) If I needed
any more common variable capacitors, I'd still be pulling them out of
radios, which are a lot more common and local than ordering by mail.
Yes, esoteric projects (relative speaking) like 900MHz power amplifier
will require out of the ordinary parts.
ANd of course, the design of the project will impact on getting parts.
Some are made to use common parts, but like those old HEP replacement
parts, they may end up being "hard to get" simply because the original
builder has chosen from a single source or from a place that everyone
is supposed to have access to (such as Radio Shack) but the proprietary
parts numbers make them less findable elsewhere). If someone decides
to use a microcontroller, either for the sake of doing so or because
they think it makes it easier for the builder, it ends up becoming a problem
since there is no replacement unless one just starts from scratch.
Michael
