Not all DB series connectors are created equal Martin. Typical Radio
Shack units are crap to say the least, and have cyclic lifespans (the
number of times you can plug/unplug mating connectors before the level
of resistance increases to unacceptable levels) similar to what you
suggest.
The DB-15HD's that I build into customer's harnesses are rated for 400+
cycles, this due directly the design of the pin/spring contact
assemblies. Although they cost more, their (electrical) performance
decrease over the first 200 cycles is negligeable. Sideways movement in
any of this style of connectors is a non-issue given the male/female
shrouding, so you can cease worrying about this.
The average 0.100" 3pin connector that folks are accustom to are not
rated for multiple cycling, some of the units I have seen coming in on
F3x aircraft from overseas are downright inferior (so is the lead material).
Again, you get what you pay for here. High quality versions are indeed
available that do offer high cyclic-ability, but they (again) cost more
due to spring contact design that offers superior wiping without
destroying both contact mating surfaces.
I like <hehe> your "non-lapriscopic" comment, I'll have to incorporate
that term in my advertising...
regards
Martin Usher wrote:
My Stork uses a D type connector in the wing / wing mount to make all
the connections to the wing servos. I think its a quite common
arrangement on European molded planes, its convenient apart from the
servo wires being all standard three pin servo wires that are not marked
(so carelessly removing a receiver can lead to fun when replacing
it......). The arrangement is neat but its not as good as it seems, the
D types were not designed for repeated plugging and unplugging and the
get a lot of sideways pull on them during wing attachment and removal --
both would contribute to the plug failing (and such failure would be
intermittent.....bad news for a servo connector).
The standard three pin Molex type connector that's used with R/C
equipment is quite a good compromise between cost and
reliability......its probably the best connector for the job still.
Deans are also OK, they're big but at least you can solder them. I don't
think there's anything else I'd trust except maybe the plugs used with
USB connectors -- there are are actually a lot of good connectors out
there but they're not easy to buy and good connectors tend to be
expensive (especially if you want something that will take repeated
plugging and unplugging).
I will agree with Simon that we need to design in cabling as part of the
aircraft design. Not just cables, either -- room for nose weight, mounts
for servos, non-lapriscopic access to servos and linkages -- details
that really aren't that difficult to get right during the design and a
nuisance to add after the fact.
Martin Usher
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Simon Van Leeuwen
RADIUS SYSTEMS
PnP SYSTEMS - The E-Harness of Choice
Cogito Ergo Zooom
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