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Common SMD size

Q

qrk

Jan 1, 1970
0
Hello Michael,

Besides the 1206 and 0805 that John mentioned there is also MINI-MELF.
They are round which can be good and bad. I kind of like them because
you can loosen the tweezer grip a wee bit, roll them onto the pads, tack
one side and then solder.

Regards, Joerg

I like MELFs for inboard components. Insert the component in a hole
and solder to pads on the top and bottom of the board.

Otherwise, stick with 0805 or 1206 as you can hand assemble quite
easily - unless you have the coffee jitters. 0603 and 0402 can be hand
assembled, but tends to be a very unpleasant task.
 
Spehro Pefhany skrev:
Drug and dollar stores? Why don't you go to a proper optometrist and
optician (ophthalmologist wouldn't hurt either at your age, he or she
will check for glaucoma), lay down a few Franklins, and get some nice
purpose-made optical wear. Your eyes will thank you.

absolutely, theres just too many variables; distance between eyes,
strenght for
each eye, etc...

I wear glasses (-3.5 or theres about) and I've tried to buy a pair of
ultra cheap one
size fits all just to have and extra pair and they are just about
useless

-Lasse
 
J

Joerg

Jan 1, 1970
0
Hello Lasse,
absolutely, theres just too many variables; distance between eyes,
strenght for
each eye, etc...

I wear glasses (-3.5 or theres about) and I've tried to buy a pair of
ultra cheap one
size fits all just to have and extra pair and they are just about
useless

They are ok if the eyes just age normally. I can work just fine with the
cheap ones and so does my wife. And our neighbors. Of course, if one eye
develops worse than the other that's a different story. Then I'd get
prescription glasses as well.

BTW a camera-TV setup is great for SMT but only for folks who can get
used to looking into a different direction than where the work area is.

Regards, Joerg
 
C

Carl Smith

Jan 1, 1970
0
Sheesh! Not my cup o' tea, thanks - I guess I'll go the FPGA route and
let somebody else solder the stuff down. ;-P

Cheers!
Rich

When I worked for a while at one of the major computer
manufacturers in the desktop systems engineering department I
learned to solder SMT stuff rather well when reworking prototype
motherboards. I could hand solder 0402 caps and resistors
without much trouble. We did have a binocular microscope and
fiber optic light and a good soldering iron though.

It looks really weird in the microscope when you bring the
solder into view and it is a "giant" metal rod twice the
diameter of the SMT part. Yup, I used plain old fine roll
solder. Oh, and if something possesed me to put a drop of
liquid flux on the part it looked like a big flood on the PCB.
:)
 
R

Rich Grise

Jan 1, 1970
0
Spehro Pefhany skrev:

absolutely, theres just too many variables; distance between eyes,
strenght for
each eye, etc...

I wear glasses (-3.5 or theres about) and I've tried to buy a pair of
ultra cheap one
size fits all just to have and extra pair and they are just about useless

I got a pair of drugstore bifocals once, and I think the bi-parts were
misaligned with my lines of sight - I got terrible eyestrain headaches
after about 15 minutes. Now I have a 1.75 or so for the computer and a
2.0 for the crossword puzzle. I was kind of bothered when the other
day I happened to look at my TV, which is at the foot of my bed, with
my computer glasses, and it was crystal-clear. Damn! I don't want my
eyes to get even lazier! )-;

Cheers!
Rich
 
D

DJ Delorie

Jan 1, 1970
0
Carl Smith said:
It looks really weird in the microscope when you bring the solder
into view and it is a "giant" metal rod twice the diameter of the
SMT part.

You made me look. My solder is 0.020", so I'm all set unless I start
using 0201's. Now I have a better idea of how SMALL those things are,
too.

Here's my setup: Optivisor with 3.5x lens[1], Metcal STTC-043 tip
(0.020" conical), and a Panavise model 333 board holder. Oh, and
pointy-sharp tweezers. I've only gone down to 0805 so far, but that
didn't seem that small.

[1] http://www.woodcraft.com/family.aspx?familyid=4227
[2] http://www.panavise.com/f/vises/vises_cbholders.html
 
J

James T. White

Jan 1, 1970
0
Jim Thompson said:
But you're still just a baby ;-) ... I'm just weeks away from 66 :-(

He just said that he passed 40, but not how many miles back :)
 
P

Phil Hobbs

Jan 1, 1970
0
John said:
Tsk tsk. It's sad what years of sniffing Krazy Glue can do to a fine
mind.
(lol)

It's more the repeated blows to the head...the Krazy Glue helps keep the
loose bits from falling off and inconveniencing passers-by.

I still want to see the pictures of that snap rectifier gizmo. Could
make a very cute Pockels cell driver.

Cheers,

Phil Hobbs
 
J

John Larkin

Jan 1, 1970
0
(lol)

It's more the repeated blows to the head...the Krazy Glue helps keep the
loose bits from falling off and inconveniencing passers-by.

I still want to see the pictures of that snap rectifier gizmo. Could
make a very cute Pockels cell driver.

Cheers,

Phil Hobbs


I posted some pics of the mechanical assembly to a.b.s.e. If you like,
I can privately send you schematics and stuff, and maybe even reveal
the secret semiconductor we discovered. My original application,
ripping atoms off samples in a 3d atom probe, has been replaced by
femtosecond lasers. Oh well, I did get some shares of stock, which I
am confident will buy me a bicycle in my retirement.

John
 
P

Phil Hobbs

Jan 1, 1970
0
I posted some pics of the mechanical assembly to a.b.s.e. If you like,
I can privately send you schematics and stuff, and maybe even reveal
the secret semiconductor we discovered. My original application,
ripping atoms off samples in a 3d atom probe, has been replaced by
femtosecond lasers.

Being replaced by a fs laser isn't so bad...could have been a computer. ;)

Since I work for the Sirius Cybernetics Corporation, getting stuff like
that is a little dicey for me, much as I appreciate the offer. Maybe
you and I and perhaps one or two other people should write a book on
circuits specifically for instruments. There's a _lot_ of cool tricks
that ought to be preserved and transmitted, and not a lot of appropriate
recipients graduating at the moment, more's the pity.

That way you'd at least get some useful advertising in exchange for all
the trade secrets. Not that there are that many people who'd even be
able to _build_ a circuit like that, even from a book, but we must live
by hope.

(Maybe we can needle Jim T enough to get him off his duff with his book,
which would be another good deed.)

Cheers,

Phil Hobbs
 
Rich said:
I got a pair of drugstore bifocals once, and I think the bi-parts were
misaligned with my lines of sight - I got terrible eyestrain headaches
after about 15 minutes. Now I have a 1.75 or so for the computer and a
2.0 for the crossword puzzle. I was kind of bothered when the other
day I happened to look at my TV, which is at the foot of my bed, with
my computer glasses, and it was crystal-clear. Damn! I don't want my
eyes to get even lazier! )-;

Cheers!
Rich

Don't worry Rich, the lenses won't make your eyes lazy.

General reading glasses' considerations:

They may bug you if the lenses' centers aren't spaced the same as
your eyes are when converged on your work. If the lens is off-center
with your pupil, prismatic distortion results, which displaces objects
laterally from the position expected/predicted by the focusing effort
now needed to focus on them. (The apparent displacement is also likely
different for each eye.) Vertical displacement is disorienting, even
nauseating.

The result is that your extra-ocular muscles clash from the
conflicting cues--e.g. simultaneously trying to _converge_ to match the
focusing effort, and _diverge_ to line up the images from the two eyes.
Fighting each other is tiring, producing a headache ("eyestrain").

These difficulties can be avoided or fixed by
1) just practicing and getting used to the lenses, if the adjustment
isn't too severe,
2) using weaker lenses and longer working distances,
3) getting lenses with the correct spacing (IP / "interpupillary
distance"), or
4) using an optical aid with built-in prismatic correction, like the
OptiVisor-style head-mounted magnifier (very nice, and not expensive).
The latter, ideally, allows *you* to look straight ahead and focus at
'infinity' while the device focuses and redirects your line-of-sight to
the workpiece, thus avoiding any strain at all.

The distortions and problems increase rapidly with stronger lenses,
but, being ideally myopic, t'ain't a problem for me--I can usually get
by with no lenses at all :-\

If you're pre-presbyopic, e.g. <40 years old, you can use reading
glasses to train yourself to reduce myopia by a diopter or so.

Cheers,
James Arthur
 
J

John Larkin

Jan 1, 1970
0
Being replaced by a fs laser isn't so bad...could have been a computer. ;)

Since I work for the Sirius Cybernetics Corporation, getting stuff like
that is a little dicey for me, much as I appreciate the offer. Maybe
you and I and perhaps one or two other people should write a book on
circuits specifically for instruments. There's a _lot_ of cool tricks
that ought to be preserved and transmitted, and not a lot of appropriate
recipients graduating at the moment, more's the pity.

Sounds like fun. I'm in.
That way you'd at least get some useful advertising in exchange for all
the trade secrets. Not that there are that many people who'd even be
able to _build_ a circuit like that, even from a book, but we must live
by hope.

The advertising doesn't matter, but maybe we can peel off a few of
Win's groupies.
(Maybe we can needle Jim T enough to get him off his duff with his book,
which would be another good deed.)

Nah, only liberal weenies do stuff that's good for humanity.

John
 
P

Phil Hobbs

Jan 1, 1970
0
John said:
Sounds like fun. I'm in.

Terrific. You write and I'll direct. ;) Let's think about some topics
and exchange them.

BTW, all, please chime in with suggestions for things to include. No
more than 20% pet peeves, please. (Well, maybe 60%--this is s.e.d,
after all.)
The advertising doesn't matter, but maybe we can peel off a few of
Win's groupies.

Nonononono. Might catch the never-get-overs. Besides, they're mostly
male and probably poorly groomed.
Nah, only liberal weenies do stuff that's good for humanity.

An excellent start.

Cheers,

Phil Hobbs
 
K

Keith

Jan 1, 1970
0
Drug and dollar stores? Why don't you go to a proper optometrist and
optician (ophthalmologist wouldn't hurt either at your age, he or she
will check for glaucoma), lay down a few Franklins, and get some nice
purpose-made optical wear. Your eyes will thank you.

Because, like pens and pencils, I don't buy good ones because I lose them.
I don't use them often enough to keep track of 'em and learned long
ago the only way I'd have such things when I needed them was to saturate
the area, so I'd have one whenever I needed one. I can't affort do
saturate the area with Franklins. I *know* where they are, and they don't
break when I sit on them.

I talked to an optometrist a while back. She even recommended the
cheapies for occasional use, with weaker ones for slightly longer viewing.
 
J

John Larkin

Jan 1, 1970
0
If you're pre-presbyopic, e.g. <40 years old, you can use reading
glasses to train yourself to reduce myopia by a diopter or so.

I like being myopic. One of these years soon I think I'll get some new
lenses, and I'm going to make sure the doctor leaves me this way.
Being fixed-focused at infinity sounds like a real nuisance in my
business.

John
 
K

Ken Smith

Jan 1, 1970
0
On Tue, 31 Jan 2006 17:55:46 GMT, Joerg [....]
easily - unless you have the coffee jitters. 0603 and 0402 can be hand
assembled, but tends to be a very unpleasant task.

On doing 0402s.

You need non-magnetic tweezers and good eyes to do 0402s. The other thing
to have is a bunch of extras of each part. If you drop one its gone even
if you drop it onto the PCB.

After you finish, turn the PCB upside down to let the lost parts fall off.
 
S

SioL

Jan 1, 1970
0
Ken Smith said:
On Tue, 31 Jan 2006 17:55:46 GMT, Joerg [....]
easily - unless you have the coffee jitters. 0603 and 0402 can be hand
assembled, but tends to be a very unpleasant task.

On doing 0402s.

You need non-magnetic tweezers and good eyes to do 0402s.

And totally clean tweezers, too. A bit of flux or even moist will
make the part stick to the tweezers after you've released them.

Can be frustrating.
 
B

Bob Monsen

Jan 1, 1970
0
I like being myopic. One of these years soon I think I'll get some new
lenses, and I'm going to make sure the doctor leaves me this way.
Being fixed-focused at infinity sounds like a real nuisance in my
business.

I've got one myopic eye and one presbyopic eye. Strange, but it lets
me read (and see smd parts) and yet also read street signs at a distance,
both without glasses. It was annoying earlier in life to be basically
blind in one eye for distances greater than 1m, particularly for sports in
which stereo vision comes in handy, but has turned out to be quite useful.

--
Regards,
Bob Monsen

"I have called this principle, by which each slight variation, if
useful, is preserved, by the term Natural Selection"
-- Charles Darwin
 
John said:
I like being myopic.

Right - I'm not especially near-sighted, but enough so I can
*read* SMD markings that my barely-myopic s.o. can't even see!
One of these years soon I think I'll get some new
lenses, and I'm going to make sure the doctor leaves me this way.
Being fixed-focused at infinity sounds like a real nuisance in my
business.

John

Not to worry...the doc can't change your eyes' optics, the source
of your myopia, and can set your glasses to any working distance
you specify.

(Lawfully, (s)he must, however, insist that you have at least
one set of specs yielding 20/40 acuity (~=resolution) for driving,
or caution you not to.)

Best,
James
 
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