Amateur electronics in danger due to lack of DIP ICs - Page 2

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Re: Amateur electronics in danger due to lack of DIP ICs
On 2/22/2021 9:24 AM, Deane Williams wrote:
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The number of COTS integrated *solutions* that are available makes many
"build from parts" solutions inefficient.

I built a combination garage door opener from CMOS logic ~50 years ago.
Today, I'd put a CMOS MCU (bought *on* a PCB) to work on the job.

Your particular needs may force you to embrace SMT -- but that doesn't
mean all hobbyists face your dilemma!  Many are delighted to just
buy a COTS board and adapt/modify it to their needs.



Re: Amateur electronics in danger due to lack of DIP ICs
On 22/02/21 16:24, Deane Williams wrote:
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For amateur purposes, experiment with dabbing on solder paste
with a jewellers screwdriver and doing the soldering in a frying
pan.

The process is fun to watch; no doubt there are many yootoob
videos showing what happens.

Or see https://www.sparkfun.com/tutorials/59

Re: Amateur electronics in danger due to lack of DIP ICs
THANKS everyone for your inputs. There are several very good suggestions here. It seems like people have branched out on how to solve this problem and I need to see which way will work best for my situation.
Best,
Dean

Re: Amateur electronics in danger due to lack of DIP ICs

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Let it bridge, then use solder wick to remove the excess.

search google for prototyping Manhattan style.

You will get a lot of related styles.
  



--  
The best designs occur in the theta state. - sw

Re: Amateur electronics in danger due to lack of DIP ICs
wrote:

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Stick with DIL/leaded/through-hole. To hell with SMD. I absolutely
refuse to use them.
 --  

"Andrey Semyonovitch really was rather stupid; he attached himself to the
 progressive cause and 'our younger generation' from enthusiasm. He was one
 of the numerous and varied legion of dullards, of half-animate abortions,
 conceited, half-educated coxcombs who attach themselves to the idea most
 in fashion, only to vulgarise it and who caricature every cause they serve,
 however sincerely."

     - Fyodor Dostoevsky

Re: Amateur electronics in danger due to lack of DIP ICs
tirsdag den 23. februar 2021 kl. 00.47.48 UTC+1 skrev Cursitor Doom:
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well, if you only use 30 year old parts ...


Re: Amateur electronics in danger due to lack of DIP ICs
On 2/22/2021 6:08 PM, Lasse Langwadt Christensen wrote:
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...and make physically large devices!

Most of my current designs are components top and bottom.  Let
the fab house deal with it!  (so, *my* goal is to get quantities
of each design *up* to make it more affordable, even in protos)


Re: Amateur electronics in danger due to lack of DIP ICs
Don Y wrote:

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Size is not always a problem. I am more concerned with the flexural  
stress of various origins. How is it supposed to be relieved if there  
are no pins? They act like small springs and can absorb a lot.

I have seen many examples of high-reliability Soviet military devices  
which used PCB as a mechanical carrier only. There was no maze; all they  
used were pads connected to the parts with very short tracks. Then they  
connected those pads with wires. Crazy expensive, but it could withstand  
really high g conditions.

    Best regards, Piotr

Re: Amateur electronics in danger due to lack of DIP ICs
On 2/24/2021 1:09 AM, Piotr Wyderski wrote:
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Yes, but you can find other ways of limiting the mechanical stresses that the
board experiences.  Note, also, that SMT packages tend to be smaller, overall
(the days of the M68k aircraft carriers are long past).  There's only so much
flexing that can occur over a short distance without damaging the board,
itself.

[I worry more about lead-free solder]

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I've worked on flight-line instruments constructed with wire lacquered onto
an FR4-like substrate.  Very disturbing to see traces *crossing* and not
instinctively think they are shorted!  The substrate is just a "support"
("carrier", in your terminology) for the chips and other components.

Re: Amateur electronics in danger due to lack of DIP ICs
Don Y wrote:
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Multiwire.  A pretty good technology in its time.

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Amateur electronics in danger due to lack of DIP ICs
Phil Hobbs wrote:



Multiwire was the high-end technology and it happens to be still  
available today if you come with a pocket big enough:

https://www.ma.showadenko.com/products_pwb_05.htm

The wires were embedded in an epoxy matrix and the technology supports  
vias. I was referring to a more typical approach, like this:

https://youtu.be/kKjchciO_wc?t36%1

    Best regards, Piotr

Re: Amateur electronics in danger due to lack of DIP ICs
On Wed, 24 Feb 2021 10:47:27 -0500, Phil Hobbs

I LOVED Multiwire.  I contracted to M&M Mars, the candy company, for a
couple of years designing machine control systems from scratch.  Mr
Mars thought that his competitive advantage was designing machinery
which could run faster and perform more functions that what one could
buy off the shelf.

My major job was designing the control system for a very high speed
wrapping machine (1800 bars/minute).  PLCs of that vintage were far
too slow so I used the old but wonderful Motorola HTL (high threshold
logic).  Ran on 15 volts, almost completely immune to noise but it
consumed a massive amount of power.

The control system was two 16 slot STD-bus racks.  Each card, made by
multiwire, had 16 pin sockets packed touching each other.

The machine was variable speed, as we could wrap more candy that the
line produced.

HTL was so wonderful to work with.  Absolutely no protection on lines
coming in from the outside, the input impedance was so low.

I REALLY hated when MultiWire went out of business.  I had to go back
to mylar, tape and Letraset to manually lay out PCBs and then find
some PCB house who would deal with a small customer.

John

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Re: Amateur electronics in danger due to lack of DIP ICs
neonjohn wrote:

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Google is of little help here, mostly some historic info. Do you recall  
the threshold voltages?

The only gates I was able to find appear not to  contain any form of  
hysteresis at their inputs. So where does the increased noise margin  
come from?

    Best regards, Piotr


Re: Amateur electronics in danger due to lack of DIP ICs
On 25/02/2021 6:57 am, Piotr Wyderski wrote:
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I only encountered HTL once, as I recall Vil was 0 to 6V and Vih was  
above 8V. The chips had zener level shift in series between the input  
stage and output stage.

piglet


Re: Amateur electronics in danger due to lack of DIP ICs
On Mon, 22 Feb 2021 17:08:34 -0800 (PST), Lasse Langwadt Christensen

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Tin whiskers aside, there's nothing whatsoever wrong with 30 year old
parts. I should mention I'm speaking as an amateur experimenter, not a
cutting edge designer working on current commercial projects.

 --  

"Andrey Semyonovitch really was rather stupid; he attached himself to the
 progressive cause and 'our younger generation' from enthusiasm. He was one
 of the numerous and varied legion of dullards, of half-animate abortions,
 conceited, half-educated coxcombs who attach themselves to the idea most
 in fashion, only to vulgarise it and who caricature every cause they serve,
 however sincerely."

     - Fyodor Dostoevsky

Re: Amateur electronics in danger due to lack of DIP ICs
On 22/02/21 23:47, Cursitor Doom wrote:
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I was concerned before I first did SMD assembly. It was easy,
and now I prefer it.

The OP shouldn't listen to reactionary old farts that refuse
to keep learning and experimenting.

Re: Amateur electronics in danger due to lack of DIP ICs
On 2/23/2021 8:40 AM, Tom Gardner wrote:
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I've grown to realize that there are so many things that I *must*
do that it is foolish for me to waste time doing things that others
can do better (and cheaper!).

As my boards get smaller and more dense, assembly just becomes a
needless timesink that I'd prefer to avoid.  So, I usually lean on
colleagues to make use of their manufacturing capabilities to
squeeze in a run of boards for me.

Even a couple of hundred isn't THAT much of an imposition.

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Yeah, but he should think hard about where his time is most useful.
Unless he's building one-offs, there's almost certainly something else
he (and ONLY he!) could be doing while someone else is doing the mundane
assembly work.

It's also good "practice" to get feedback on the design/layout issues
that might need to be tweaked before scaling up to full production.

[The same applies to your documentation package and test procedures...
you won't know where they are deficient if you are inherently relying on
knowledge that exists in your head to silently supplement those efforts]


Re: Amateur electronics in danger due to lack of DIP ICs
On Mon, 22 Feb 2021 08:24:38 -0800 (PST), Deane Williams

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(Hi Guys.  I'm back :-)

You make a full commitment to SMD and never look back.  First you
download the free and professional grade PCB-CAD program called KiCAD.

You lay out your board using SMD devices.  Then you buy the parts.
Finally you send the Gerber files, along with print-outs of each side
of the board to one of the many houses who both make the boards and
then stuff them.

For repair you'll need a fine tipped soldering iron and a hot air
source AUOE sells both in one box for under $200.  And you'll need
some fine tweezers, solder paste and water soluble flux.

Finally a stereoscope.  Since I do commercial work I spent the money
for a used Mantis.  Instead of eyepieces you have to lean over, the
mantis projects the stereo against a black background that you simply
look at.  John Larkin has a Mantis and can rave more about it.

An additional handy accessory is a set of heated tweezers.  These
allow you to solder SMD discretes, both ends at once.

If you need to attach or replace a 0.5mm IC, you'll use the hot air
system to remove it.  Clean the pads with solder wick  Lay the new
chip on the pads, apply some flux to opposite corners and hand-solder
those two pins to hold them in place.  Then use whatever method you
have (I have an air-operated solder paste dispenser with suck-back) to
dispense the paste.  Melt the solder paste with the hot air gun.
You'll have 4 solid rows of solder, shorting all the pins.  Use solder
wick to remove the excess solder.  The wick will remove all the
exposed solder but will not affect the solder between the legs and the
pad.  You're done.

Don't even think of using lead-free solder unless you want constant
headaches.  Use the good old leaded solder paste.  The flux is water
soluble so give the board a good scrubbing with dishwasher detergent
and dry it in an oven set to 150 deg F.

I would NEVER go back to thru-hole construction, even for prototypes.

I use 4 layer, power and ground PCBs.  The two inner layers are power
and the most prevalent power, usually 3.3 or 5 volts.  The two outside
layers are the routable layers.

Routing an SMD board, especially a dense one, is trivially simple
compared to thru-hole with just 2 layers.

John


Re: Amateur electronics in danger due to lack of DIP ICs
On Mon, 22 Feb 2021 22:06:58 -0500, Phil Hobbs

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My box builder has a row of at least 20 residential dishwashers.  All
boards come off the line and into those dishwashers.  Even
water-soluble flux boards.  That is the way to clean boards.  I know
they use a detergent but I don't know which.

John

Re: Amateur electronics in danger due to lack of DIP ICs

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