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  #11  
Old 01-07-2017, 04:03 AM
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rmartingt rmartingt is offline
 
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Are we referring to these?



I'm using them for trim servos, especially my aileron trim (custom-built tab), because there's not enough room to get a D-sub where it needs to go.
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  #12  
Old 01-07-2017, 04:16 AM
mturnerb mturnerb is offline
 
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Quote:
Originally Posted by rmartingt View Post
Are we referring to these?



I'm using them for trim servos, especially my aileron trim (custom-built tab), because there's not enough room to get a D-sub where it needs to go.
The Stein Air method uses dsub pins as connectors wire-to-wire, shrink wrapped so it takes even less space than a micro molex. So no need for an actual dsub connector, just the pins. The shrink wrap can be split to disconnect.
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  #13  
Old 01-07-2017, 10:14 AM
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mike newall mike newall is offline
 
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Originally Posted by rvbuilder2002 View Post
Different strokes for different folks....

If you search the forums you will find lots of posts from people who like the micro molex connectors a lot.

And many who need counselling after struggling with them.......

It is the Curse of the Wereengineer

They use them because they can
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  #14  
Old 01-07-2017, 10:29 AM
maus92 maus92 is offline
 
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How much power (amps @ 12v) can a DB9 handle?
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  #15  
Old 01-07-2017, 11:44 AM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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Default Aeroelectric method

I suspect that the SteinAir method is actually the Aeroelectric (Bob Nuckolls) method. He just didn't post a youtube video. What Stein's video doesn't show is that you can 'stagger' the pins by clipping each mating pair longer/shorter than its neighbor(s). When you do that, you can keep the overall joint diameter almost as small as the wire itself, and it will 'key' each mating pair by length.

To answer maus92's question, current capacity is measured by capacity per pin; not the number of pins. The machined pins are rated at around 7 amps each. Most of us limit them to around 5A each, but you can use multiple pins for higher current. The technique is to use 20 awg 'ballast' wires ~12" long on each pin, and collect them into a splice with the main (heavier) conductor. The ballast wires provide a method to terminate into the small barrel of the pin, and help balance distribution of the current among the common pins.

Note that for something like trim motors, it's not amp ratings that is likely to bite you. There's almost no power carried there (it will run off a 9V transistor radio battery), and most of the wires just carry 'signal'. At those low levels, joint resistance is the big enemy, and molex style connectors are not gold plated. The Dsub pins are gold plated, and tend to be much more reliable in less than ideal environments.

All the above is covered in the Aeroelectric Connection book, and on the Matronics list.

edit: As mentioned, there's wide variation in opinion about this style pin. It's worth pointing out that the primary reason mfgrs moved from soldered joints to crimped joints was not joint reliability of a properly soldered joint, or stress risers in soldered joints (crimped terminals have them, too). The reason was two-fold: it's faster to train a line worker to squeeze a ratcheting crimper until it releases than to train him in how to make a reliable solder joint, and it's faster during production runs to crimp a joint using a pre-insulated terminal than it is to solder and then insulate/strain relief. The reason I mention this is that, as stated here, many have problems making up these miniature molex style connectors properly, but few have problems with Dsub pins, which they must master for the rest of their avionics anyway. Why not go the the known-reliable components *and* techniques?

Charlie

Last edited by rv7charlie : 01-07-2017 at 11:54 AM.
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  #16  
Old 01-07-2017, 03:16 PM
tgmillso tgmillso is offline
 
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Quote:
Originally Posted by rv7charlie View Post
At those low levels, joint resistance is the big enemy, and molex style connectors are not gold plated. The Dsub pins are gold plated, and tend to be much more reliable in less than ideal environments.
Whilst I am in agreement that gold connectors are a good thing in these low current applications, the connectors for the Molex plug specified at the top of the page are the SL seriese if I am not mistaken. I have found both tinned and gold plugs available for them, below is an example.
http://www.digikey.com.au/product-de...3TR-ND/1656192
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  #17  
Old 01-07-2017, 05:09 PM
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JohnInReno JohnInReno is offline
 
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Default D-sub solder pins

Quote:
Originally Posted by czechsix View Post

Another technique I've seen for a low profile installation is to crimp D-sub pins & sockets on the servo and wire harness terminations, but instead of inserting them into D-sub connectors, simply plug them together with a piece of heat shrink over each pin/socket connection to insulate them and keep them from coming apart. This would not be a good idea if the wiring is ever likely to get yanked, but if it's properly supported/protected this is a clean way of connecting the servo to the harness without the bulk of a connector.

YMMV...
I used this technique with staggered wire lengths. I found it easier to solder the skinny wires than crimp them. Reconnecting was necessary after painting.
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  #18  
Old 01-07-2017, 06:56 PM
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Jesse Jesse is offline
 
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Originally Posted by JohnInReno View Post
I used this technique with staggered wire lengths. I found it easier to solder the skinny wires than crimp them. Reconnecting was necessary after painting.
That's where the good Daniels crimpers make a difference. I was never happy with a crimp on 26AWG wire into Dsub pins until I got the Daniels crimper.

Solder splices work really well for these types of connections as well.
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