[sdiy] DIP LM13700 discontinuation

sleepy_dog at gmx.de sleepy_dog at gmx.de
Thu May 20 10:07:19 CEST 2021


thresholdpeople via Synth-diy:
> I like these DIP to SOIC adapters for prototyping on a breadboard, or
> for retrofitting SMT parts into through hole boards:
> https://www.sparkfun.com/products/13655. The related items feature
> boards for pins with all sorts of pin counts.

On ebay one can often find better bang/buck offers for those things,
esp. if buying a few more (at least at German ebay I have bought a bunch
of those before)


> Though I too think SOIC isn't any harder to deal with than through
> hole, and can be dead-bugged pretty easily as well when the adapters
> aren't available.

For lower pin count things like a dual op amp, it might also not be too
laborious to do "split pads" on perfboard. I.e. if the perfboard quality
is good enough, with a sharp knife, you can cut a (electrically) clean
crack in the center of a copper circle, making two pads out of it, do
that with 7 more and easily solder the SO opamp on it.
I have seen perfboard with spacing  of SO pins, though. It's just not
cheap. Although, you could design some and have a cheap PCB service make
it, even with some or all plated-through holes / double sided. They are
cheap when you order more of the same.

> Maybe fewer people into DIY have SMT soldering experience, for now,
> but no one starts out knowing how to solder anyway, and these are
> skills that are learned and incrementally improved.

Yeah, and then you better do get into SMT. There is no reason for parts
manufacturers to keep producing DIP parts - and it seems silly to quit
electronics DIY out of some sort of resentment (even if David's comment
was half in jest, just as an example), wouldn't it . There is nothing in
it for the manufacturers, hardly anyone buys that stuff.
One does not have to be a robot to solder SMT, to the contrary, one has
to acquire human-friendly techniques to be able to solder certain SMT parts.
And then, for anyone who already uses services like JLCPCB - adding SMT
mounting doesn't cost that much more, even though their stock is mostly
good for not too special parts only, the rest you'll have to do
yourself. But all the fiddly little resistors and ceramic caps, or
single SMT transistors - let them do it.
I did SMT early on, to 1) yes, make things smaller - whoever only wants
to do modules with all its own controls on it won't be impressed here,
but there are other ways of doing things ;)  2) to use parts that only
ever existed as SMT. Sometimes really small / fine pin pitch (where you
can drag-solder on the PCB, applying lots of flux before - no robot
work). Prototyping with that, I did not feel like a robot, more like an
electric surgeon. And using a microscope when I was 30, it won't make me
feel extra old when I need it for more things than used to once 50, I
guess ;)


> And at that scale, the rework is also not hard, and I think it's far
> easier to actually properly desolder SMT parts than through hole.
There it would seem that smaller parts are easier - heat it all up with
the hot air station (the cheap ATTEN 858D+ does it),
which would seem difficult with SOIC of that pin count. (OK it's also
not fun with e.g. UFQFPN with a nasty thermal sink in the middle)

IIRC I never de-soldered a SOIC - how *do* you do that? Flux and wick
still leaves a little bit of connecting solder on many pins at the same
time?
I faintly remember once using a piece of lacquer insulated copper wire,
dragging it under the first heated pin in line, then the next, and so
forth, where the wire keeps the pins from the pads. That was not as big
a part, though.




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