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  1. #1
    Join Date
    13th September 2017
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    35

    Looking for connector for breakaway wiring harness

    Hi all. I am looking for a (preferably) 2 conductor connector (male and female) for a breakaway harness to deliver current to a remote deployment charge from the AV bay.

    I have used the search function on the forum, and have seen a couple, but not exactly what I am looking for.

    I am guessing that someone here knows of a quality connector that will mount one fitting on an end cap of the AV bay, and the other end to terminate the leads on an e-match. On deployment, it needs to be able to pull away smoothly. Only 2 conductors necessary. I am aware of 'twist and tape', and am confident that I could use that, but it is also not what I am looking for.

    Any links or mention of preferred parts would be greatly appreciated.


    I know I could go searching at Allied or Mouser and find something, but maybe I don't have to reinvent the wheel?


    Cheers!


  2. #2
    Join Date
    17th February 2014
    Posts
    517
    Quote Originally Posted by Chris_H View Post
    Hi all. I am looking for a (preferably) 2 conductor connector (male and female) for a breakaway harness to deliver current to a remote deployment charge from the AV bay.

    I have used the search function on the forum, and have seen a couple, but not exactly what I am looking for.

    I am guessing that someone here knows of a quality connector that will mount one fitting on an end cap of the AV bay, and the other end to terminate the leads on an e-match. On deployment, it needs to be able to pull away smoothly. Only 2 conductors necessary. I am aware of 'twist and tape', and am confident that I could use that, but it is also not what I am looking for.

    Any links or mention of preferred parts would be greatly appreciated.


    I know I could go searching at Allied or Mouser and find something, but maybe I don't have to reinvent the wheel?


    Cheers!
    I've never done a breakaway connector, but I thought if I did these magnetic connectors might work. https://www.dyna-snap.com/

    NAR
    L1: 2/2/13, Madcow 4" Patriot. CTI H143
    L2: 9/2/14, Madcow 4" AGM33 Pike. CTI J335. 2,878 ft, 418 mph
    L3: 1/7/17, Wildman Drago XL. AT M1500. 13,559 ft, 1,017 mph, Mach 1.2

  3. #3
    Join Date
    13th September 2017
    Posts
    35
    Maybe. Those do look cool, but they also look like they might have some mass to them, then they might not be so reliable in a high-G or high vibration situation.

    I want some kind of socket that mounts to the bulkhead so that the plug will be pushed down into itself with gravity, in addition to the pins giving support.

  4. #4
    Join Date
    13th June 2014
    Location
    Cocoa Beach, FL
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    3,447
    I have never used them myself but I have read on several threads here where people have used these for breakaway connections for staging.

    https://www.ebay.com/itm/10-pairs-14...4AAOSwA3dYejDW
    Tim
    L3 NAR 98225

  5. #5
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
    Posts
    1,145
    I like Molex Micro-Fit 3.0 series. They are positive locking for when you want that. If you want to pull away you can cut the locking tab off. Good contact retention and reliability IMHO.
    https://www.digikey.com/product-deta...1783-ND/252496
    https://www.digikey.com/product-deta...761-ND/1132437
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    These are quite robust and not too small and fiddly. Good current capability too.

    I usually just glue the plug housing into the endplate of the avionics bay.

    For extra brownie points you can protect the pins from corrosion (from ejection gases) by filling the connectors with something like CG153 contact grease by Electrolube, or something similar.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  6. #6
    Join Date
    5th January 2012
    Location
    Des Moines, IA
    Posts
    171
    try adept
    http://www.adeptrocketry.com/CAB2cart.htm
    Adept Rocketry - Accessories - CAB2-xxD Disconnect Cable
    Nik B.
    TRA 6035 L3

  7. #7
    Join Date
    13th September 2017
    Posts
    35
    Cool. Those all look good. Not a chassis mount socket, but good anyway.


    Thank you.

  8. #8
    Join Date
    6th February 2015
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    653

  9. #9
    Join Date
    21st April 2010
    Location
    So central WI, USA
    Posts
    5,373
    hmm, has the 2.5mm dc power plug been mentioned? or the mini plug(mini headphone/ earbud/ earphone)?
    Rex
    L2-competitor 3, AT J350W, 8/27/2016, Bong, 2557'
    my youtube channel http://www.youtube.com/channel/UC0gB...?feature=watch

  10. #10
    Join Date
    13th September 2017
    Posts
    35
    Rex, I saw mention of that somewhere else on the forum. I like the little molex connectors better.

    One issue I see with the mini plugs you mention, is that they are substantial pieces of metal, and if the direction of pull was from the wrong direction, it would require a wire breaking to release. Of course a male and female jack for each of these could be had, terminated in wire on each one, that would reduce any issues with hanging up. I know the likleyhood is slight, but I think there are better options. Given, if one of these jacks did hang up at the first tension, it would probably shake free immediately after.

    An ideal connector will be easy to connect and safely 'stack' the bit of slack to the harness nearby in a manner that it does not risk premature disconnect, and that, at the given time, it just slips free, not dependent on direction of pull.

  11. #11
    Join Date
    11th January 2012
    Location
    Commonwealth of VA
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    1,527

    -Bill Riley

    TRA: 12294
    NAR: 89196

    A good rule for rocket experimenters to follow is this: always assume that it will explode.
    Astronautics, issue 38, October 1937.


  12. #12
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
    Posts
    1,145
    Watch out using the earphone-style connectors for anything serious. They rely on the sideforce imposed by the tip contact(s) to push the plug sideways to get the outer (probably ground) contact connected. They sort of work OK unless there are other forces on the plug, and then all bets are off.

    They also tend to short as they are plugged in sometimes, so by implication they can short as they are separated.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  13. #13
    Join Date
    13th September 2017
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    35
    Quote Originally Posted by Worsaer View Post
    This is what I use. The downside is that you need to manually crimp the little connectors... Also, that looks like it would be used to connect two of the wire housings, one on either end?

    https://www.mouser.com/Search/Produc...538-22-05-3031
    https://www.mouser.com/Search/Produc...538-22-01-3037
    https://www.mouser.com/Search/Produc...538-08-50-0114

    I was looking at those earlier. How do you mount the header to the bulkhead? Any pictures of those in place?

  14. #14
    Join Date
    13th September 2017
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    35
    Quote Originally Posted by OverTheTop View Post
    Watch out using the earphone-style connectors for anything serious. They rely on the sideforce imposed by the tip contact(s) to push the plug sideways to get the outer (probably ground) contact connected. They sort of work OK unless there are other forces on the plug, and then all bets are off.

    They also tend to short as they are plugged in sometimes, so by implication they can short as they are separated.

    Yep, agreed. I am familiar with those sorts of connectors, they do not 'feel' right, at all, for the reasons you mention.

  15. #15
    Join Date
    1st May 2011
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    Utah Canyon Country
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    Quote Originally Posted by nraymondb View Post
    try adept
    http://www.adeptrocketry.com/CAB2cart.htm
    Adept Rocketry - Accessories - CAB2-xxD Disconnect Cable
    I can wholeheartedly recommend these......used them a few times, always successful......small, no excess bulk, light, easy/simple.
    Definitely a good way to go.

    s6
    - Yes, I did a search before posting. -

  16. #16
    Join Date
    11th January 2012
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    Commonwealth of VA
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    1,527
    Quote Originally Posted by Chris_H View Post
    I was looking at those earlier. How do you mount the header to the bulkhead? Any pictures of those in place?
    Sorry I don't have any current photos, as my toys are tucked away in storage. That being said, two ways I have used them.

    1) Solder wire leads to the pins, with the wires being long enough to work with. Drill matching holes in fiberglass AV bay lids, feed the wires through, then 'pot' the fixed connector with epoxy. I use this approach if space is an issue.

    2) My preferred approach: I use the following items on most of my AV bay bulkheads, then simply insert the fixed end in and screw it down. This provides a reliable breakaway connection in a screw terminal.

    https://www.mouser.com/Search/Produc...key651-1715048

    -Bill Riley

    TRA: 12294
    NAR: 89196

    A good rule for rocket experimenters to follow is this: always assume that it will explode.
    Astronautics, issue 38, October 1937.


  17. #17
    Join Date
    13th September 2017
    Posts
    35
    Quote Originally Posted by Worsaer View Post
    Sorry I don't have any current photos, as my toys are tucked away in storage. That being said, two ways I have used them.

    1) Solder wire leads to the pins, with the wires being long enough to work with. Drill matching holes in fiberglass AV bay lids, feed the wires through, then 'pot' the fixed connector with epoxy. I use this approach if space is an issue.

    2) My preferred approach: I use the following items on most of my AV bay bulkheads, then simply insert the fixed end in and screw it down. This provides a reliable breakaway connection in a screw terminal.

    https://www.mouser.com/Search/Produc...key651-1715048

    Thank you.

  18. #18
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
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    1,145
    Phoenix also have a range of pluggable terminal blocks. Basically a screw terminal block with separable halves.
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    I have used them on my 1/2 scale Nike Smoke.
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    The left one pulls out when the NC separates from the airframe. The one on the bulkhead had two eMatches for the ARRD, but stays connected for the whole flight.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  19. #19
    Join Date
    13th August 2014
    Posts
    787
    What about an RCA style connector? For only two conductor it would be a good fit. You could use a bulkhead connector on the bay and something like this: https://www.parts-express.com/rca-ma...ector--090-102
    On the other end.

    Sent from my HTC6535LVW using Rocketry Forum mobile app
    -Brian Schwartz
    LiquidFyre Rocketry
    https://www.LiquidFyre-Rocketry.com
    TRA #15327 L2



    If it's worth doing, it's worth over doing!

  20. #20
    Join Date
    27th March 2013
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    Quote Originally Posted by Ravenex View Post
    What about an RCA style connector? For only two conductor it would be a good fit. You could use a bulkhead connector on the bay and something like this: https://www.parts-express.com/rca-ma...ector--090-102
    On the other end.

    Sent from my HTC6535LVW using Rocketry Forum mobile app
    I was thinking the same thing... However, they can be hard sometimes to pull out, but if you're using them in conjunction with a large enough separation charge, I don't see where they could fail to separate.
    Dreaming of making the rockets I dreamed of as a kid (and then some).


    NAR L1 Cert flight: Sheridan, Oregon, USA. Sept. 19, 2015. Flew Deep Space OFFl on an I357T-14A Blue Thunder

  21. #21
    Join Date
    11th January 2013
    Location
    Old Bridge,,,,,,,,,,,,, New Jersey
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    5,048
    Quote Originally Posted by timbucktoo View Post
    I have never used them myself but I have read on several threads here where people have used these for breakaway connections for staging.

    https://www.ebay.com/itm/10-pairs-14...4AAOSwA3dYejDW
    +1....

    I built a scratch 3" airframe w/ a 54mm central and 2-- 38mm outboard motor mounts..
    I call it Europa Express.. Tourism,, get it,, lol..

    There's a Europa Express flight at the end of these pics...

    http://onebadhawk.com/metra-812015.html

    Well,, in order to do the air starts I use the JST connectors Tim has pointed out..
    I thought about a simple wire twist,, that would do the airstart fine,,
    but wouldn't be consistent in the amount of force it takes to be yanked apart on the separation event..
    Those magnetic 2 conductor plugs look severely cool but I don't think they'd tolerate all the dirt and grime build up...
    The JST connectors last for 3 or 4 flights then must be changed..
    The year before last year I was at Airfest in Kansas and intended to light a Loki L 1040 LR in the 54 / 2800 case on the pad,,
    and light 2 -- Aerotech J 575 FJ in the 38 / 1080 case in the air...
    On my table after a lot of work the rocket was prepped for flight and ready to go...
    I powered up each altimeter to check that everything was in order..
    The primary altimeter said I do not see continuity on a channel that I am supposed to according to the way you have me set...
    I took things apart,, put things back together and checked again with the same result...
    I looked for an hour... I couldn't find the problem and scrubbed the flight...
    After I got home I found the problem,, the JST was due for a change,, new plugs,, that was the channel the altimeter didn't see continuity on..
    If the altimeter hadn't caught the problem the flight would have been safe,, just an awful lot lower apogee,, lol...
    This rocket has over a dozen flights on it at this point,, this is the only occasion that I had an anomaly with this connection point...
    I stand by these connectors for this purpose..
    They are reliable,, make a solid connection,, take a consistent amount of pressure to yank apart,,
    and are inexpensive- can be replaced after just a couple of flights...

    Teddy




    www.Onebadhawk.com

    Ted Chernok
    Old Bridge New Jersey
    METRA- BoD- New York..
    URRG- Way upstate New York..
    MDRA- Maryland..
    QCRS- Illinois- Best politicians money can buy ( Tim L. )..
    Kloudbusters- Kansas..
    NAR # 87063
    Tripoli # 14443
    Level 3

  22. #22
    Join Date
    13th September 2017
    Posts
    35
    There are too many types of RCA's to generalize, but most of them are going to be very sensitive to direction of pull. If the direction of pull is out of line by a relatively narrow degree, the required disconnect force goes up really quickly.

  23. #23
    Join Date
    19th February 2009
    Location
    Auburn, WA USA
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    1,939
    Coming back to rockets as I do from an RC background if I were doing it, I'd use 2-pin Deans connectors. I'd just pot the female in epoxy through a rectangular hole in the bulkhead. https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXCGP1

    These are also available polarized...with one male and one female in each half, but you can easily do that yourself by swapping the pins between the housings.

    The picture in the Tower listing doesn't give a sense of scale. The bodies of these are about 1/8 inch by 7/32 inch in cross section. The pins are a little over 1/8 inch apart.

    I know from using these in small electric RC airplanes that they can safely handle 10A for periods of several seconds at a time.
    Bernard Cawley
    NAR 89040 L1
    AMA 42160
    KG7AIE

  24. #24
    Join Date
    18th January 2009
    Location
    Crofton, MD
    Posts
    678
    I've been truing to find the connectors like the ones shown on the adept website. What type of connector are they? I thought they were deans connectors, but the ones I have, the male ends have a radius on them. Thanks!
    MDRA Member
    TRA Level 2

  25. #25
    Join Date
    13th September 2017
    Posts
    35
    Quote Originally Posted by BEC View Post
    Coming back to rockets as I do from an RC background if I were doing it, I'd use 2-pin Deans connectors. I'd just pot the female in epoxy through a rectangular hole in the bulkhead. https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXCGP1

    These are also available polarized...with one male and one female in each half, but you can easily do that yourself by swapping the pins between the housings.

    The picture in the Tower listing doesn't give a sense of scale. The bodies of these are about 1/8 inch by 7/32 inch in cross section. The pins are a little over 1/8 inch apart.

    I know from using these in small electric RC airplanes that they can safely handle 10A for periods of several seconds at a time.

    These look like the ticket. I am ordering some to see if I like them.


    I have been wondering about whether a static mounted fitting might not be as good as both connections 'in the wire' in order to help insure a more inline direction of pull. Still, these Dean connectors look like they would pull apart pretty easily, yet be secure enough.

  26. #26
    Join Date
    9th July 2014
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    Phoenix, AZ
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    1,431
    Quote Originally Posted by Crazyrocket View Post
    I've been truing to find the connectors like the ones shown on the adept website. What type of connector are they? I thought they were deans connectors, but the ones I have, the male ends have a radius on them. Thanks!
    They are just a "female header connector". Many different styles, but that'll point you in the right direction and you can find one you like.

  27. #27
    Join Date
    18th January 2009
    Location
    Austria
    Posts
    739
    Quote Originally Posted by Rex R View Post
    hmm, has the 2.5mm dc power plug been mentioned?
    For club projects, we have used panel mount barrel connectors in break away applications - although in 5.5mm size - and they have worked fine so far. I'm not sure how well they keep contact during times of high vibrations/accelerations, but this is usually not a problem when it is time to ignite deployment charges, as long as the connector doesn't get unplugged during the high stress phase of flight.

    Reinhard

  28. #28
    Join Date
    21st November 2012
    Posts
    16
    I have used Deans - type connectors with mixed success. Had to be sanded to slip apart. I have to transfer them to a new e-match for each flight, so they're quite fiddly. I've had good results with them, except when they separated under g-load.

    I've also used two parallel wires shrink-wrapped together. Again, kind of fiddly, but it works and the price is right.

    Sent from my SAMSUNG-SGH-I337 using Rocketry Forum mobile app

  29. #29
    Join Date
    19th January 2009
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    Stafford VA
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    6,956
    I just got some 1S batteries with female JST plugs. I didn't have any male connectors to use with them, so I used shooter wire from old ematches to wire them to the electronics. I just stripped 1/4" to 3/8" off the wire and inserted it into the female connectors. It was snug, but not too tight I had trouble inserting. It keep a good electrical connection and pull apart pretty easily.

    If you use a female JST mounted solid, you should be able to insert the ends of the ematch and it will hold well but slip out when pulled. No fiddly with putting connectors on the ematch wire.
    Last edited by Handeman; 12th November 2017 at 03:05 PM.
    Handeman

    TRA #09903 L3 3/29/2015

    "If you don't use your head, you have to use your feet!" my Dad

    Tripoli Central Virginia #25 - BattlePark.org

  30. #30
    Join Date
    26th November 2009
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    4,603
    If using a "break" connection between two segments of the rocket that is not held with shearpins, I'd suggest that one allows some wire "slack" between the two segments.

    Ever notice on some of the rocket videos where you can see the sustainer is working free of the ebay but stayed together just long enough to make it to apogee?

    If there was a "fixed" break connection, in that situation, it might "break" before it was supposed to. Allowing so there can be some separation of the pieces before
    the connection is severed seems prudent to me.

    Kurt


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