Things started off with a failed motor after the last crash. Turned out a wire sheered off from flexing during a crash long ago & the other 2 wires were nearly broken off. No way to spot it without removing the heat shrink tubing. There's no flex tolerance in those $12 motors. This in addition to a minimum PWM setting that was too low after a firmware update may have been causing flips for a while.



Next, it was off to test a new GPS derived heading algorithm & a 25 year old flash. This was the EOS 5D's lightest configuration with a flash.





















The 25 year old flash wasn't much dimmer than the modern $400 580EX II but took forever to recharge. The GPS derived heading seems better.


Now the results of the new algorithm. Commanded & detected heading should be as close as possible.







Except for a few transients, it actually seemed to do better.

Finally, for those of you who use laptops initially instead of rendering 3D models of home made groundstations & buying laptops later, it's time to hack the Targus.

Targus deliberately prevented hackers from splicing unusual connectors to their power supplies by requiring a logic circuit in their connectors to turn on the power supply. Your only recourse to use a custom connector is some diabolical soldering & Dean.










Views: 290

Comment by bGatti on August 6, 2010 at 9:45am
Soldered wire ends do this shearing a lot, the solder binds the copper together and creates a very small stress point, so every movement is expressed in the same millimeter of wire - and the same is true for every strand, so the weakness becomes concentrated at the solder joint, far better to secure the wire mechanically. Plus, if it's current carrying, the initial weaknesses increase the temperature at one point.
Comment by Patrick Hammer on August 6, 2010 at 1:54pm
A quick note regards soldering: yes, indeed - soldering does create a localised point, where vibration and repeatative movement over time can lead to stress/fatigue faliure.

It's no garuntee against ultimate failure, but adhesive lined shrink tubing will usualy hold 2 broken wire ends in close enough proximity to each other - sufficiently long enough for intermitant/poor contact to be recognised, localised and responded to.

Developer
Comment by Doug Weibel on August 6, 2010 at 3:05pm
Patrick - nice tip. Do you procure adhesive lined shrink tubing (never seen it myself, but haven't looked), or do you shoot some adhesive in yourself? What kind of adhesive?

Developer
Comment by John Arne Birkeland on August 6, 2010 at 3:26pm

Comment by Earl on August 6, 2010 at 3:46pm
Looks like you could omit the solder and have a good connection and not create a 'stress point' with the above pics !
Earl
Comment by bGatti on August 6, 2010 at 5:01pm
When I have an ugly connection (back of deans etc) I like to cut a bit of hotglue and stuff it into the tubing, then when I apply heat - good things happen.
Comment by bGatti on August 6, 2010 at 5:04pm
The above solder joint looks better than it works. Note that the two wire lengths only touch each other in the loop, most of the solder is applied to the same wire touching itself. Plus it has two weak spots.

Developer
Comment by Michael Smith on August 6, 2010 at 5:13pm
@Doug - Try something like these:

http://www.smallparts.com/s/ref=sp_search?searchNodeID=383597011&am...
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1704112&am...

I've also seen it at West Marine, though the smaller sizes can be hard to find.
Comment by bart ureel on August 6, 2010 at 5:20pm
I would suggest using inline splices instead of soldering on this type of connections. In aviation we barely use solders , only to connect to pcb's or direct connections to components.

Developer
Comment by Michael Smith on August 6, 2010 at 5:32pm
@John - That works OK for fine wire, but not so well for the magnet wire that was an issue for the OP.

Another approach that can work well if you have the space is to run the two wires side-by-side and butt-join them. With the shrink over both wires it moves the bending force away from the stress risers at the edge of the solder and the edge of the insulation (which is also where you tend to nick the conductors when stripping).

Here's a not very good illustration:


cribbed without permission from http://www.rcgroups.com/forums/showpost.php?p=4496262&postcount=94

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