Req: The benefit of your sagacity

[gregor]

Is there a source of information you can recommend that deals with the more escoteric
aspects of component selection?
I know what a transistor is and what it does but is there a recommended purpose for metalic
vs carbon film type?
The same with capacitors. When do you use ceramic, taladium, electrolytic?
The main reason I ask is that often components mentioned in construction articles are very
specific as to type.
Sometimes these components are no longer available or difficult to obtain. I'd like to know
when and how substitutions can be made.
The answer is usually "it comes from experience". At 61 I don't have a great deal of time
to accumulate much experience and am hoping there is a reference available.

 

[Rich Grise]

On Fri, 14 Sep 2007 19:21:57 +0000, gregor wrote:

Is there a source of information you can recommend that deals with the more escoteric
aspects of component selection?
I know what a transistor is and what it does but is there a recommended purpose for metalic
vs carbon film type?
The same with capacitors. When do you use ceramic, taladium, electrolytic?
The main reason I ask is that often components mentioned in construction articles are very
specific as to type.
Sometimes these components are no longer available or difficult to obtain. I'd like to know
when and how substitutions can be made.
The answer is usually "it comes from experience". At 61 I don't have a great deal of time
to accumulate much experience and am hoping there is a reference available.

OK, how about "it depends"? ;-)

The thing is, I'm 58, and still don't know the advantages/disadvantages of
carbon film vs. metal film. I just buy whatever's cheaper in the catalog.

Ceramic caps have moderate capacitances, can work with fairly high
voltages, and have good high-frequency perrormance, but they can have
high ESR, microphonics, piezoelectric effects - i.e., the capacitance
can change with applied voltage. And the cheaper ones can be used as
temperature sensors. ;-)

Tantalums are electrolytics made of tantalum instead of aluminum; these
days, when they separate them as you did, the "electrolytic" refers to
aluminum cans. The aluminum ones have the highest capacitance per unit
volume, but have very wide tolerances and are polarized. Tantalums are
polarized, don't have as wide a tolerance, and are smaller than an
equivalent aluminum, probably better ESR and stability, but either
kind can explode spectacularly if you give it too much or the wrong
polarity voltage.

For small cap values, silver mica are the most temp. stable, tightest
tolerance, and best HF performance, but they're expensive and don't
come in very big values.

Mylar, polyester, (which are actually the same stuff), polystyrene,
film, etc. work with moderate voltages, have small to moderate
capacitances, and excellent to superb leakage.

Oh, yeah, aluminums are usually relatively leaky.

I'm afraid I'll have to leave transistor and inductor selection as an
exercise for the student - heck, it couldn't take more than a few hours
to learn how to read a data sheet, and inductors are black magic anyway!
;-)

Have Fun!
Rich

 

[John Larkin]

On Fri, 14 Sep 2007 22:55:59 GMT, Rich Grise <rich@example.net> wrote:

On Fri, 14 Sep 2007 19:21:57 +0000, gregor wrote:

Is there a source of information you can recommend that deals with the more escoteric
aspects of component selection?
I know what a transistor is and what it does but is there a recommended purpose for metalic
vs carbon film type?
The same with capacitors. When do you use ceramic, taladium, electrolytic?
The main reason I ask is that often components mentioned in construction articles are very
specific as to type.
Sometimes these components are no longer available or difficult to obtain. I'd like to know
when and how substitutions can be made.
The answer is usually "it comes from experience". At 61 I don't have a great deal of time
to accumulate much experience and am hoping there is a reference available.

OK, how about "it depends"? ;-)

The thing is, I'm 58, and still don't know the advantages/disadvantages of
carbon film vs. metal film. I just buy whatever's cheaper in the catalog.

Kids these days!

Carbon film resistors change resistance a lot with temperature,
hundreds of PPM/K. Cermets, the most common surface mount resistors,
are better, 100 PPM maybe. Metal films and wirewounds are best, 50 ppm
to as low as a few. If precision matters, pick accordingly. For audio,
buy whatever's cheapest.

John

 

[gregor]

You folks are fantastic. I get the feeling I'm not alone with this problem. There's a book in
this for someone who has the required skill set. It would be a good thread to work up.
Thanks for all your efforts. As they say "You da bomb." At least I think they still say that!

 

[Michael Black]

gregor (gregor@kafka) writes:

Is there a source of information you can recommend that deals with
the more escoteric aspects of component selection?
I know what a transistor is and what it does but is there a recommended
purpose for metalic vs carbon film type?
The same with capacitors. When do you use ceramic, taladium, electrolytic?
The main reason I ask is that often components mentioned in construction
articles are very specific as to type.
Sometimes these components are no longer available or difficult to obtain.
I'd like to know when and how substitutions can be made.
The answer is usually "it comes from experience". At 61 I don't have a
great deal of time
to accumulate much experience and am hoping there is a reference available.

I suspect many of us did learn from experience, so other methods

are not in our realm.

One thing about construction articles, sometimes they are specific
because there is a real reason for a specific component, and other
times they specify what they used (in effect saying, "try something
else at your own risk"). They may specific because the specific
is readily available, at least to them, or because they don't want
all kinds of questions asking "but what kind of capacitor should I
use at C1".

Though hopefully, when a specific type is necessary, it will have
something like "use only polypropolene capacitors here" rather
than "the .1uF capacitors are polyproplene" (the former indicating
there are no options, the latter an indicator of what was used
by the builder).

Not really useful, but it is background.

One thing about specific capacitors, one necessity is that the larger
the value, the harder it is to get that sort of capacitance in a reasonably
sized package. Hence, the move to electrolytics and tantalum (which
causes and incidental move to polarized capacitors, since the makeup
of such capacitors cause them to be polarized).

So small value capacitors, 20pF, might be chosen for high tolerance,
because much variation from the marked value could affect circuit
operation. But, that too is variable, because a coupling capacitor
might not be a problem, while tuning an LC circuit it would. You
might also choose a type of capacitor that isn't affected by temperature,
since again a small variation might affect circuit operation.

Ad capacitance goes up, their tolerance is less important, because
the circuits needing larger capacitance generally aren't fussy. The
caveat being that if the capacitor is used for timing or some tuned
circuit, precision is likely a factor.

So some types of capacitors are more stable with temperature, and
others are available in smaller tolerances.

One way of looking at it is the more general something is, the project
or the use of that capacitor, the cheaper the capacitor can be, and
thus the cheaper the capacitor, the less it matters what type.

When I was a kid, you'd use electrolytic capacitors for any value
over 1uF (because that's about all you could get in such high
values, and if you found any non-electrolytic of that value or
higher, they tended to be really large). Polarized because
that's the only option electrolytic capacitors provided.

..1 and .01uF, so common as bypass capacitors, they'd be ceramic.

Smaller values tended to be ceramic or better silver mica.

You didn't fuss over brand, you bought what was available, what
was cheap, or better yet scrounged what you could.

IN recent years, I've seen people fuss over specific brands, and
fuss over what type capacitor to use for really general applications,
which is fallout from a) a wider range of methods to manufacture
capacitors and b) it's all out there in the catalogs for everyone
to see. It start becoming complicated because the variety is there,
rather than because that much has changed.

You look at schematics, and read the theory beside them. You start
to note how common it is to bypass an emitter, you start to see the
handful of basic uses of capacitors (bypass, coupling, timing or
tuning), and you discard the fuss over some things, and then
that leaves just a few capacitors that would ever need to be
fussed over (and even then, with more thought and study, that
number drops even further).

You used to be able to get books on every single type of component.
I suspect you still can, but they are no longer aimed at hobbyists
and thus at the very least carry a high price. But a book like
that on capacitors is bound to tell you far more than you'll
ever need to know on the subject.

Manufacturer's literature might be helpful, though I suspect little
is being published on paper nowadays. Dig out the names of the
big capacitor companies, and look for their websites, to see if
they have any info there.

Michael

 

[Don Bowey]

On 9/14/07 12:21 PM, in article 46eadf55$0$33812$d368eab@news.calweb.com,
"gregor" <gregor@kafka> wrote:

Is there a source of information you can recommend that deals with the more
escoteric....

(snip)

At 61 I don't have a great deal of time to accumulate much experience and am
hoping there is a reference available.

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

 

[Michael Black]

Don Bowey (dbowey@comcast.net) writes:

On 9/14/07 12:21 PM, in article 46eadf55$0$33812$d368eab@news.calweb.com,
"gregor" <gregor@kafka> wrote:

Is there a source of information you can recommend that deals with the more
escoteric....

(snip)

At 61 I don't have a great deal of time to accumulate much experience and am
hoping there is a reference available.

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

More like he thinks the end goal is more important than the trip.

Which I realize could equally apply to getting old as much as
learning things.

Michael

 

[Rich Grise]

On Sat, 15 Sep 2007 01:17:12 +0000, gregor wrote:

You folks are fantastic. I get the feeling I'm not alone with this
problem. There's a book in this for someone who has the required skill
set. It would be a good thread to work up. Thanks for all your efforts.
As they say "You da bomb." At least I think they still say that!

Heck, this is USENET. People say anything they want to. ;-)

Welcome to the asylum! ;-)

Cheers!
Rich

 

[Rich Grise]

On Sat, 15 Sep 2007 09:11:05 -0700, Don Bowey wrote:

On 9/14/07 12:21 PM, in article 46eadf55$0$33812$d368eab@news.calweb.com,
"gregor" <gregor@kafka> wrote:

Is there a source of information you can recommend that deals with the more
escoteric....
(snip)
At 61 I don't have a great deal of time to accumulate much experience and am
hoping there is a reference available.

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

Oh, foo. Haven't you heard? 60 is the new 40! ;-)

Cheers!
Rich

 

[Don Bowey]

On 9/15/07 9:27 AM, in article fch163$164$1@theodyn.ncf.ca, "Michael Black"
<et472@FreeNet.Carleton.CA> wrote:

Don Bowey (dbowey@comcast.net) writes:
On 9/14/07 12:21 PM, in article 46eadf55$0$33812$d368eab@news.calweb.com,
"gregor" <gregor@kafka> wrote:

Is there a source of information you can recommend that deals with the more
escoteric....

(snip)

At 61 I don't have a great deal of time to accumulate much experience and am
hoping there is a reference available.

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

More like he thinks the end goal is more important than the trip.

Which I realize could equally apply to getting old as much as
learning things.

Michael

Well put.

 

[Michael Black]

Don Bowey (dbowey@comcast.net) writes:

At 61 I don't have a great deal of time to accumulate much experience and am
hoping there is a reference available.

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

More like he thinks the end goal is more important than the trip.

Which I realize could equally apply to getting old as much as
learning things.

Michael



Well put.

That was sort of a glib response, but there is truth to it.

One could spend years learning the needed stuff, and even if
there were "cheat sheets" it would take time to cover enough to
do whatever he presumably wants to do.

Or one could more or less jump in, learning from the experience
and actually doing things now.

I've posted before about the first few electronic projects
I tried to build, and they never worked. I didn't have enough
skill to put them together properly (it's easy now to realize
how bad my soldering was back then, but how was I supposed to
know at the time?), and not enough skill or knowledge to properly
figure out what wasn't working.

Yet at some point, you have to take those first steps. If I'd
waited "until I'm ready", it could have been years in the future,
and I'd still have to make that first attempt and it might not
have worked then either.

The good thing was I didn't get discouraged. I kept reading
and learning, and oddly enough, when I did get something to
work, admittedly simpler things that those already simple
projects, I was putting them together with parts I'd torn
out of transistor radios and surplus computer boards (from
a time when surplus computer boards had transistors). That
first audio oscillator that did work, I bypassed the soldering,
and just twisted the leads together. I can't even remember how
I figured out how that scrap transistor was NPN.

The odd thing is that between those first failed projects (and
they were spread months apart, since I was buying the parts new
and my allowance didn't grow on trees) and getting that audio
oscillator to work (and then that crystal oscillator), it
was no more than a year, yet I'd picked up lots of important
notions about components and what I was supposed to use.

Hence I was able to pick over parts yanked off scrap boards
to make things that worked, and I was no longer so dependent
on those parts lists in the hobby magazines.

The trick to any learning is that it always looks like a steep
cliff when you are approaching it. But once you move along a bit,
when you look back it doesn't look nearly as steep. You have to
forget about how high the cliff is so you don't get discouraged.

Michael

 

[Don Bowey]

On 9/15/07 9:10 PM, in article fciabe$liq$1@theodyn.ncf.ca, "Michael Black"
<et472@FreeNet.Carleton.CA> wrote:

Don Bowey (dbowey@comcast.net) writes:

No, I didn't write this:

At 61 I don't have a great deal of time to accumulate much experience and
am
hoping there is a reference available.

I wrote this:

With that ageism attitude, I don't hold out any hope you will ever acquire
much knowledge. You have all but given up already.

And you wrote this:

More like he thinks the end goal is more important than the trip.

Which I realize could equally apply to getting old as much as
learning things.

Michael

And I wrote this:

Well put.

And you wrote.......

That was sort of a glib response, but there is truth to it.

One could spend years learning the needed stuff, and even if
there were "cheat sheets" it would take time to cover enough to
do whatever he presumably wants to do.

Or one could more or less jump in, learning from the experience
and actually doing things now.

I've posted before about the first few electronic projects
I tried to build, and they never worked. I didn't have enough
skill to put them together properly (it's easy now to realize
how bad my soldering was back then, but how was I supposed to
know at the time?), and not enough skill or knowledge to properly
figure out what wasn't working.

Yet at some point, you have to take those first steps. If I'd
waited "until I'm ready", it could have been years in the future,
and I'd still have to make that first attempt and it might not
have worked then either.

The good thing was I didn't get discouraged. I kept reading
and learning, and oddly enough, when I did get something to
work, admittedly simpler things that those already simple
projects, I was putting them together with parts I'd torn
out of transistor radios and surplus computer boards (from
a time when surplus computer boards had transistors). That
first audio oscillator that did work, I bypassed the soldering,
and just twisted the leads together. I can't even remember how
I figured out how that scrap transistor was NPN.

The odd thing is that between those first failed projects (and
they were spread months apart, since I was buying the parts new
and my allowance didn't grow on trees) and getting that audio
oscillator to work (and then that crystal oscillator), it
was no more than a year, yet I'd picked up lots of important
notions about components and what I was supposed to use.

Hence I was able to pick over parts yanked off scrap boards
to make things that worked, and I was no longer so dependent
on those parts lists in the hobby magazines.

The trick to any learning is that it always looks like a steep
cliff when you are approaching it. But once you move along a bit,
when you look back it doesn't look nearly as steep. You have to
forget about how high the cliff is so you don't get discouraged.

Michael