[TriEmbed] Favourite electrical connectors?

Fri Sep 25 12:17:52 CDT 2015


On 09/25/2015 01:06 PM, Carl Nobile wrote:
> Pete,
>
> What Charlie is trying to do is create a board that the people working 
> on the CANInstall spec can use as a base line tool. We won't be using 
> long cables for this initial work.
>
> I like the RJ11 for some things, but it needs to mate with a flat 
> cable which by its nature can't be twisted, CAT cables won't mate to 
> it without a lot of extra work. We need, as Charlie just told me,
Tell this to the fractional billions of people using RJ45 connectors. 
They're identical to RJ11 but eight vs six connections. I agree 200% 
that inserting and crimping UTP into an RJ45 or RJ11 is a certified, 
genuine pain in the you know what, but figured labor costs in this case 
are considered zero. :-)

-Pete

> four wires, two for the CAN protocol and two for power. Each one will 
> go to some sort of sensor.
>
> ~Carl
>
>
> On Fri, Sep 25, 2015 at 12:46 PM, Pete Soper via TriEmbed 
> <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>
>     The cable requirement for CANBUS is explicitly dictated by the bus
>     standard (covered in this TI blurb
>     <http://www.ti.com/lit/an/slla270/slla270.pdf>): you'll be using
>     120 ohm twisted pair. Accommodating the 120 ohm termination
>     resistors needed at the two ends of the bus is a side issue that
>     might interact with connector choice. The easy choice for cable is
>     UTP (aka CAT3/5/6) with as few twisted pairs as you can get by
>     with (since canbus only uses one pair). Somebody recently gave
>     away hundreds of feet of this stuff at a TriEmbed meeting, so I
>     think this is a good choice.
>
>     The bus is only two wires, plus one more for an optional shield.
>     So a very simple connector will do it. IMO the lowly RJ11 will get
>     the job done. I have three crimping tools you can borrow. :-) The
>     male connectors are cheap as dirt. Here's a Digikey jack
>     <http://www.digikey.com/product-detail/en/A-2014-0-4-R/AE10390-ND/2183641>
>     (35 cents at Q50). Some of the "big boys" use RJ45, but I can't
>     see the need for that and it's just extra cost wrt PCB area.
>
>     The lowly RJ11 combined with UTP cable might be a practical
>     solution. The connector is "keyed", trivial to get in and out, but
>     stays in place. You could also arrange a convention where a
>     termination resistor could either be crimped into two additional
>     connector sites (so the termination is part of the cable) or
>     handled on the PCB. A weather boot would be used for cases where
>     crud might get inside the connector, as it is highly exposed.
>     Using dielectric grease to exclude oxygen would be a good idea too
>     for cases where the connection is going to be exposed.
>
>     -Pete
>
>
>     On 09/25/2015 10:18 AM, Charles West via TriEmbed wrote:
>>     Hello,
>>
>>     I'm working on a board for the CanInstall autoregistration
>>     project and I'm not really sure what connectors to use for it. 
>>     I'm currently leaning toward either DF13-4 connectors or simple 4
>>     pin headers.  If I may ask, are there any other connectors that
>>     you would recommend or have used in your projects?
>>
>>     Pros/cons:
>>     DF13:
>>     The upside is that they are very small, connect very securely and
>>     SMD female connectors are $.41 per.  The downside is that they
>>     are extremely hard to get out (don't pull on cable, very gently
>>     pry with finger nail on one side, then the other) and cables for
>>     them are extremely hard to find/expensive ($1.5 per in lots of 20
>>     is the cheapest I've found).
>>
>>     Vertical Headers:
>>     The plus is I can get break apart SMD headers at roughly $.05
>>     each including shipping at lots of $5
>>     (http://www.ebay.com/itm/10pcs-2-54MM-1-40Pin-SMD-SMT-1-40Pin-Male-Single-Row-Pin-Header-/261879748701?hash=item3cf93fd85d),
>>     cables at $.22 per in lots of $5
>>     (http://www.ebay.com/itm/20pcs-2-54mm-to-2-54mm-Dupont-Wire-Cable-Connectors-4P-to-4P-Pin-Header-20cm-YG-/111487505711?hash=item19f52c552f)
>>     and they are pretty standard for hobbyist projects (and extremely
>>     similar to servo connections).  The downsides are that they have
>>     no polarity control, are much more likely to slide out and take
>>     up a lot more board real estate (translating to either bigger
>>     boards or less connectors).
>>
>>     Thanks,
>>     Charlie
>>
>>
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>
>
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>
>
>
>
> -- 
> -------------------------------------------------------------------------------
> Carl J. Nobile (Software Engineer)
> carl.nobile at gmail.com <mailto:carl.nobile at gmail.com>
> -------------------------------------------------------------------------------

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