On 10/28/23 3:32 PM, David Higton wrote:
> In message <BuudnQ1ot_sf96H4nZ2dnZfqn_GdnZ2d@earthlink.com>
> "56d.1152" <56d.1152@ztq9.net> wrote:
>
>> On 10/27/23 12:32 AM, The Natural Philosopher wrote:
>>> On 27/10/2023 04:44, 56d.1152 wrote:
>>>
>>>>
>>>>    Solder IS the best.
>>>>
>>> No, actually it often isn't...
>>>
>>> The problem with solder on *stranded* wire is that it wicks up the wire
>>> and reduces it's flexibility by binding the strands together: That
>>> creates a stress concentration where it stops and a likely cause of
>>> fracture failure under vibration. That is why crimps are the choice for
>>> cheaper connections in high stress environments (e.g. automotive) or if
>>> you must solder you absolutely need to mechanically support the wire
>>> upstream of the solder joint.
>>
>> I've had very bad luck with 'crimps' - esp when they are
>> exposed to the weather, but even in higher-vibration
>> environments. Wasted lots of time trying to track down
>> problems related to crimps.
>
> I still remember a very interesting one in the 1980s with a joystick
> for a Sinclair Spectrum.

DID have one ! :-)

> The box proudly proclaimed the use of gold
> plating in the internal connections. They used fully (i.e. not
> selectively) gold plated crimps onto stranded tinned copper wire.
> One of the joints, although completely mechanically sound, was not
> conducting electricity. Yes, that really was the interface between
> the crimp and the wire.
>
> I ran solder in and it was fine.

Yep ... crimps SOUND great - until you hit
the Real World.

Crimps are a cheap quick fix.

> There is a known, but unfortunately not widely known, problem in the
> interface between gold and tin.
>
> The lesson boils down to:
>
> 1) Never mix gold plated and tin plated connectors.
>
> 2) If you're using gold plated connectors, use selectively gold plated
> crimps in them.

Material compatibility IS always important.

Gold MOSTLY works with everything but, by
experience, not ALWAYS

Soldering IS a bigger pain in the ass, no question.
But it's MUCH more sure. It'll last 20-50 YEARS under
really crappy conditions.

My old old HOUSE is mostly SOLDERED electrical
connections - not even sure how they DID that
conveniently back in the day. However I'm NOT
worried about any of those connections - mostly
in the attic/ceiling - overheating like modern
screw-terminal connections that oxidize or
where the copper compresses and becomes loose.

A couple extra hours in 1950 meant 100+
years of reliability. When (likely soon) the
house is destructed the ELECTRIC will still
be 100%

Anyway ... BAD experiences with 'crimps' under
a variety of conditions. Soldered is much more
sure. Solder, add heat-shrink to spread out
the mechanical stress and weatherproof ...
electronic nirvana ! :-)

Sorry, I'm very old-school in this respect.
I really design for 100 years safe service.

On 10/27/23 2:42 AM, Ahem A Rivet's Shot wrote:
> On Thu, 26 Oct 2023 23:44:48 -0400
> "56d.1152" <56d.1152@ztq9.net> wrote:
>
>> But, remember "wire wrap" ? Still have the tools
>> for doing that. The more-extensive wrapping CAN
>> be as reliable as soldered connections.
>
> A good wire wrap connection (done with a power tool - we always
> used Gardner-Denver) is gas tight and extremely reliable as well as being
> faster and easier to modify than soldering.

Yep. Some of those "old world" solutions can
STILL be good solutions !

And, when everything's 100%, you can always
solder the wire-wrap.

As said somewhere, one employer had a *kit* LSI-11
box. It had BASIC, but everything of use was writ
in FORTRAN. They'd worked out all the wiring issues
and soldered the wire-wrap. From there on it was
just a software box. It's STILL around in a
storage spot somewhere, I'll bet on it. And it'll
still WORK - (assuming the 8" floppies can still
be read). Oh, dual 8" Shugart floppy unit ...
weighed about 75 POUNDS, BIG transformer :-)

On Mon, 30 Oct 2023 00:51:14 -0400, 56d.1152 wrote:

>> The other gang that understand interactions between electronics and
>> vibration are model flyers: radio control models, drones and, the most
>> vibration of all, IC powered free flight competition models: a current
>> F1C class model has a 2.5cc engine putting out around 1.3 HP at 30,000
>> rpm and carrying electronic flight timers and a GPS-based radio beacon
>> as a retrieval aid. Free flight models regularly travel 2km or so in
>> the course of a 3 minute flight, especially if the contest is being run
>> on Sculthorpe, an ex-RAF/USAF base in Norfolk,UK. This area is known
>> for its fresh sea breezes.
>
> An actual hydrocarbon-fuel engine WILL create a lot of very buzzy
> vibration - which WILL take its toll on every connection. It's
> amazing how quickly some connections will fail - chips can even work
> their way out of conventional sockets.
>
> And then, if an ignition system is involved, transient electrical
> noise ! :-)
>
High performance model engines have no ignition: they're either diesels
(COMPRESSION IGNITION burning an oil/kerosene/ether mix) or gloplug
ignition (battery heated plug with platinum coil to start, when running
combustion keeps the plug hot and burning methanol/oil mix, sometimes with
added nitromethane for more power.

You quickly learn how to protect in-model electronics and associated
wiring from the engine's vibration - if you don't you'll have lots of more
or less spectacular crashes. An F1C class model can climb vertically to
around 120m with a 3 second engine run.

--

Martin | martin at
Gregorie | gregorie dot org