I'm currently using punchdown blocks to terminate network cables on my devices. But, they are considerably larger (volumetric) than I'd like. Coupled with the bend radius of the cables, it requires a larger enclosure volume than I'd like (I'm aiming for really small devices -- on the order of a couple of cubic inches). I'd ruled out the more traditional 8P8C's as they're even more bulky (and require additional labor to install). Are there other connector/termination options that might be leaner? I'm currently looking at designing a custom connector along the lines of the IDCs used for ribbon cable. But, I'd like to avoid those tooling charges and reliance on a single supplier.
CAT5e/6 connector/termination alternatives
Started by ●October 1, 2020
Reply by ●October 2, 20202020-10-02
On Thu, 1 Oct 2020 15:55:40 -0700, Don Y <blockedofcourse@foo.invalid> wrote:>I'd ruled out the more traditional 8P8C's as they're even more >bulky (and require additional labor to install).The wire spacing for 8P8C flat RJ45 connectors is about 1.05 mm. You can't get the wires any closer to each other unless you contrive a 3D connector that supports layers of 4 pair bundles. If you want more density, and can tolerate more than one CAT5/6 cable per connector, look into 25 pair telco connectors. The only problem is that these are made for CAT3 and will probably not handle gigabit ethernet speeds. <https://www.amazon.com/Amphenol-MP-5T90MMUNNA-010-25-Pair-degree-50-Pin/dp/B00O07B8NW>>Are there other connector/termination options that might be >leaner?Amp (TE Connectivity) probably has higher density connectors that might be convinced to work at gigabit speeds. I'm too lazy to dig through the catalog tonite: <https://www.te.com/usa-en/plp/connectors/Y30Dq.html> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 2, 20202020-10-02
On 2020-10-01, Don Y <blockedofcourse@foo.invalid> wrote:> I'm currently using punchdown blocks to terminate network cables > on my devices. But, they are considerably larger (volumetric) > than I'd like. Coupled with the bend radius of the cables, > it requires a larger enclosure volume than I'd like (I'm aiming > for really small devices -- on the order of a couple of cubic > inches). > > I'd ruled out the more traditional 8P8C's as they're even more > bulky (and require additional labor to install). > > Are there other connector/termination options that might be > leaner?Do you have any bandwidth requirements?> I'm currently looking at designing a custom connector along the lines > of the IDCs used for ribbon cable. But, I'd like to avoid those tooling > charges and reliance on a single supplier.what's wrong with the availalble IDC terminations? -- Jasen.
Reply by ●October 2, 20202020-10-02
On 10/1/2020 9:31 PM, Jeff Liebermann wrote:> On Thu, 1 Oct 2020 15:55:40 -0700, Don Y <blockedofcourse@foo.invalid> > wrote: > >> I'd ruled out the more traditional 8P8C's as they're even more >> bulky (and require additional labor to install). > > The wire spacing for 8P8C flat RJ45 connectors is about 1.05 mm. You > can't get the wires any closer to each other unless you contrive a 3D > connector that supports layers of 4 pair bundles.You don't need a connector body that's "thicker" than a few mm to accommodate a single row of 8 conductors. Yet, 8P8C male mated to receptacle is ~5/8" "thick". I.e., the female connector body is approx 5/8 x 5/8 x 5/8 -- you don't need all of that just to terminate 8 conductors. (the connector volume of a *40* conductor ribbon cable IDC PCB mount is less than that)> If you want more density, and can tolerate more than one CAT5/6 cable > per connector, look into 25 pair telco connectors. The only problem > is that these are made for CAT3 and will probably not handle gigabit > ethernet speeds. > <https://www.amazon.com/Amphenol-MP-5T90MMUNNA-010-25-Pair-degree-50-Pin/dp/B00O07B8NW>I don't need more than one cable termination. Note the 50pin you cited is still "bulky" -- even if you omit the volume of the backshell.>> Are there other connector/termination options that might be >> leaner? > > Amp (TE Connectivity) probably has higher density connectors that > might be convinced to work at gigabit speeds. I'm too lazy to dig > through the catalog tonite: > <https://www.te.com/usa-en/plp/connectors/Y30Dq.html>I think I'm going to try to find an 8pin IDC ribbon termination and see how well that works. I suspect if the pairs aren't overly "untwisted" it should fare as well as a "hand-made" 8P8C (if you look at how long each of the pairs need to be untwisted in each case) If that works (electrically), then I'll have a similar connector designed that makes installation easier (e.g., like "pull thru" 8P8Cs plugs)
Reply by ●October 2, 20202020-10-02
On Thursday, October 1, 2020 at 10:04:13 PM UTC-7, Don Y wrote:> I think I'm going to try to find an 8pin IDC ribbon termination > and see how well that works. I suspect if the pairs aren't overly > "untwisted" it should fare as well as a "hand-made" 8P8C (if you > look at how long each of the pairs need to be untwisted in each case)The terminations that work for stranded wire (like in most ribbons) are unsuitable for solid wire (like in most installations with in-wall wiring). So, even if it WERE to work electrically, it might fail mechanically. Since you're using telco-style punchdown blocks, you are probably using solid wire. Going through an RJ45 connector is a nice way to be able to test the wires... and disconnect a client object without disturbing the cabling.
Reply by ●October 2, 20202020-10-02
On Thu, 1 Oct 2020 22:03:56 -0700, Don Y <blockedofcourse@foo.invalid> wrote:>I don't need more than one cable termination.How about an M8 or M12 ethernet connector? <https://www.google.com/search?q=m8+ethernet+connector&tbm=isch> <https://www.google.com/search?q=m12+ethernet+connector&tbm=isch> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 2, 20202020-10-02
On 10/1/2020 10:30 PM, whit3rd wrote:> On Thursday, October 1, 2020 at 10:04:13 PM UTC-7, Don Y wrote: > >> I think I'm going to try to find an 8pin IDC ribbon termination >> and see how well that works. I suspect if the pairs aren't overly >> "untwisted" it should fare as well as a "hand-made" 8P8C (if you >> look at how long each of the pairs need to be untwisted in each case) > > The terminations that work for stranded wire (like in most ribbons) > are unsuitable for solid wire (like in most installations with in-wall wiring). > So, even if it WERE to work electrically, it might fail mechanically. > Since you're using telco-style punchdown blocks, you are probably using > solid wire.You can purchase 9P8C plugs for stranded or solid wire. So, it is obviously possible to design a "contact surface" that will handle a solid OR stranded wire. I.e., in production, that wouldn't be an issue. As to prototyping, I can sidestep the whole "contact point" issue by soldering conductors to the contact points intended to pierce/hug the individual conductors (i.e., avoid the whole issue of the connection of PCB pin to wire conductor) Or, I can select stranded CAT5 cable. The bigger issue (per my post) is the consequence of the chosen connection type to the "bounding volume" of the completed assembly. Note that a PCB header requires the cable to exit coplanar to the PCB. This isn't the case with, for example, an 8P8C receptacle. (likewise, it's obvious that you could redesign punchdown blocks for the conductors to exit normal to the plane of the PCB -- though they would have to be located along an edge of the PCB in order to be accessible to the punchdown tool.> Going through an RJ45 connector is a nice way to be able to test the wires... and > disconnect a client object without disturbing the cabling.If solid wire, then you'd want to avoid the "moving connector" or switch to stranded wire. In either case, once mated, the connection isn't expected to be "serviced". When was the last time you dicked with any of the wires for your thermostat? Doorbell? Irrigation controller? Automobile's ECU? If you design the connector, then you can address "removability" in ways that aren't possible with the 8P8C connectors (e.g., when a locking tab breaks... you can't separate the cable from the connector body). For example, if removability was a design goal, you could adopt a "hinged"/compression mechanism similar to that used for flat conductors.
Reply by ●October 2, 20202020-10-02
On Friday, October 2, 2020 at 6:42:58 AM UTC-7, Don Y wrote:> ...once mated, the connection isn't expected to be "serviced". > When was the last time you dicked with any of the wires for your thermostat? > Doorbell? Irrigation controller? Automobile's ECU?If the data throughput needs are minimal, could you fall back to two pairs, and 10/100 speed limit? POE is still possible there... and a lot of the M8 data connector literature is for four-wire Ethernet.> If you design the connector, then you can address "removability" in ways > that aren't possible with the 8P8C connectors (e.g., when a locking tab > breaks... you can't separate the cable from the connector body). For > example, if removability was a design goal, you could adopt a > "hinged"/compression mechanism similar to that used for flat conductors.The highest speeds require jumble-wound wiring, though. Some kind of handwork for separation and termination is going to be required, unlike flat cable.
Reply by ●October 2, 20202020-10-02
On 10/2/2020 1:59 PM, whit3rd wrote:> On Friday, October 2, 2020 at 6:42:58 AM UTC-7, Don Y wrote: > >> ...once mated, the connection isn't expected to be "serviced". >> When was the last time you dicked with any of the wires for your thermostat? >> Doorbell? Irrigation controller? Automobile's ECU? > > If the data throughput needs are minimal, could you fall back to two pairs, > and 10/100 speed limit? POE is still possible there... and a lot of the M8 data > connector literature is for four-wire Ethernet.I can live without the CAT6 capability (and likely will have to cuz CAT6 handles like "thin orange hose"!) I can't see how to successfully create service loops, etc. in a small space with something that stiff (it's a chore not putting kinks in CAT5e) But, I'd be unhappy downgrading to 100Mb (though I'm presently only using 100Mb) as needs rarely seem to DEcrease, over time.>> If you design the connector, then you can address "removability" in ways >> that aren't possible with the 8P8C connectors (e.g., when a locking tab >> breaks... you can't separate the cable from the connector body). For >> example, if removability was a design goal, you could adopt a >> "hinged"/compression mechanism similar to that used for flat conductors. > > The highest speeds require jumble-wound wiring, though. Some kind of handwork for separation and > termination is going to be required, unlike flat cable.Yes -- but that would also be the case if you were fitting 8P8C plugs on the ends of the cable "on site". If I design a connector, then I can make the "cable side" more friendly to on-sit wiring; create guides/channels for individual conductors instead of forcing the installer to try to keep the conductors in the "right" order and carefully aligned (I could even CHANGE the order to one that avoids the splitting of pairs BEFORE entry to the connector)
Reply by ●October 2, 20202020-10-02
On 10/2/2020 12:07 AM, Jeff Liebermann wrote:> On Thu, 1 Oct 2020 22:03:56 -0700, Don Y <blockedofcourse@foo.invalid> > wrote: > >> I don't need more than one cable termination. > > How about an M8 or M12 ethernet connector? > <https://www.google.com/search?q=m8+ethernet+connector&tbm=isch> > <https://www.google.com/search?q=m12+ethernet+connector&tbm=isch>Even worse. The "connector PAIR" has to be small. I.e., the 8P8C plug largely fits inside the 8P8C jack so doesn't ADD much to the overall volume of the device (incl connection). That's why I thought the ribbon cable IDC header was ideal; the "connector" itself is minimalist AND there is no space required for its "mate" (as there is none). The ideal would be a set of 8 thru-hole pads into which the 8 conductors could be threaded and then "cinched" without requiring the use of solder. Trim the excess conductor length poking out the far side and your only concern thereafter is strain relief (which, applied to the insulated portion of the cable, could be secured to a wide variety of surfaces without fear of short-circuit)
