[sdiy] Resistor types

[harrybissell]

"Roy J. Tellason" wrote:  <snip'd>

>
> And I wonder how often (if at all) the designers of circuits using _digital_
> stuff even consider this.  One would not expect those folks to have much
> experience with RF...

A lot of them ARE working with RF these days... the higher clock speeds are out
in FCP (cell phone) territory.   If they use an inductive part it will ring
horribly !!!

> > ...and I squint a lot :^P
>
> It sucks,  not being able to see as well as I used to!

... squints some more looking at screen...   ;^P

> > 3) Vector T42-1 terminal... wires go on the bottom, component on the top.
>
> Which one is the T42-1?  The number sounds familiar,  but I have no idea where
> my vector catalog is.
>

the T42-1 fits in an .040" diameter hole... usually on the .1" x .1" grid perf
board.
It pushes in from the top... has one hole in the bottom that takes about a 28ga
wire...
one hole in the sides of the top which will hold about a 24ga wire (useful for
bussing
common components together IF you solder very carefully) and a split top (don't
want to
say 'fork' because there is one that is exactly like a fork... and its not the T42
:^)
that can hold a component lead.

I'm using these in PTH holes (woah go figure...) on pcb to allow a component to be
changed
many, many times without trashing the PCB.   An unusual and highly recommended
procedure.

OTOH they are about 4.5 cents each  (in 1000s) so the pins are much more valuable
than a resistor...
but I think a completed PCB is worth the insurance...

> This reminds me of a job interview I went on a number of years ago.  I don't
> even remember what the product was,  only that it was a hybrid of both analog
> and digital technology,  and on a couple of fairly large (square foot or so?)
> boards.  The digital stuff was more or less like any other digital stuff but
> the analog board was chock full of both large numbers of 1% resistors and
> trimpots all over the place.  Part of my job would have been to set these
> boards up, and adjust all of those trimpots...

One engineer I used to work with tried to design out all trimpots.  Its a very
good idea
if you can manage it... if he needed a precision voltage, he made one precise, not

adjustable.   I'd like to see his take on an expo converter.

One funny story... I have a 4-20mA converter I use at work... and the cal techs
were
stumped with the interaction of the zero and span trims... I set it up in about 30
seconds
and they were amazed...

... little did they know that after zero beating several VCOs... their job was
actually dead
simple. MAYBE they'd like to try 'hard'  ???

H^) harry