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I'm working on rebuilding a design that currently uses obsolete parts. I'm taking the opportunity to increase reading accuracy. In doing so, I will have to replace our current connector to go from a 2 wire resistance measurement to a 4 wire resistance measurement for a group of devices under test and increase max DuT capacity to fill the remaining multiplexer card slots. That will takes the design to a 96 pin connection. If I go to digikey and look up a D-sub connector that has 96 pins there's only 3 active parts. That doesn't bode well for longevity of the design, but then again I'm quite new to this so I'm not sure if that's a good indicator. Maybe it's as simple as large pin connectors are uncommon in general, but I'm trying to keep this a 1 connector design to reduce risk of operator error, wear and tear, and time loss.

Is there a place I can go to gage the popularity/longevity of a connector?

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    \$\begingroup\$ I'd suggest using multiple connectors - a 96 conductor cable will be bulky and hard to handle. I'd suggest using three DC-37 connectors - that would allow 8 sensors per connector. \$\endgroup\$ Commented Mar 24, 2021 at 16:00
  • \$\begingroup\$ @PeterBennett That's definitely not a bad idea. It would make the design more scalable and make it less of a pain for the operator to plug in (and seat correctly), however the biggest concern in my case with this is the possibility of operators plugging in the cables incorrectly and thus causing false failures and traceability issues. These sensors get tested at the same bench a total of 3 times, and if just once those connectors are wrong those sensors are compromised. Of course, there's probably keyed connectors I could get, but then it gets harder to find replacements. \$\endgroup\$
    – Gimmacus
    Commented Mar 25, 2021 at 15:01

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Your approach of using a major distributor like Digi-Key to find common parts is a good one.

To determine if the part is "common" look for form-fit-function compatible parts that are...

  • In stock, with a reasonable supply
  • Listed as active
  • Made by multiple manufacturers
  • The manufacturers should be large, rather than small startup companies or similar.
  • Available from multiple distributors

In your specific case, what you should do is expand your search a bit.

Instead of looking for exactly 96 pins, try to go a few pins higher. 96 was the number of pins your design needs, but it may not be a common number. Also consider that having some spare pins allows room for growth without a complete redesign later on, so in many cases its good practice to have a few spare pins. If you look at 104 pin D-Sub connectors there are 517 options instead of 3. They are made by three vendors (Amphenol, Positronic, and TE), which are all well known names in the connector industry.

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  • \$\begingroup\$ Thanks for your insight and tips on what to look for. This will definitely be handy to reference in the future. \$\endgroup\$
    – Gimmacus
    Commented Mar 25, 2021 at 15:10
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D-sub connectors with more than 50 pins were never standard, and ones with more than 25 pins were never common. I don't think a d-sub connector is the right choice for this purpose.

If you don't need anything special in terms of signal integrity or current carrying capacity, I would recommend a simple pin header, such as this one; 0.1" rectangular pin arrays aren't going to go away any time soon, and for cables, you can get IDC connectors that just clip straight onto a ribbon cable without even needing to strip or solder anything.

The IDC connectors may become harder to find in future, as they're less popular now than they used to be, especially in such large sizes, but other types of header that will still fit the pins will likely remain available for decades to come.

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  • \$\begingroup\$ At my previous employer we frequently used DC37 connectors in our data acquisition system. \$\endgroup\$ Commented Mar 24, 2021 at 15:57
  • \$\begingroup\$ @PeterBennett Sure, as I said, they're not common, but they do exist and are standard. \$\endgroup\$
    – Hearth
    Commented Mar 25, 2021 at 1:09
  • \$\begingroup\$ @Hearth Signal integrity is pretty important as we have some pretty tight tolerances to adhere to, any readings that are shaky have a pretty good likelihood of breaking those tolerances without the DuT actually falling out of spec from those values. Then again, all that we're measuring on this bench is resistance so maybe it's not as important as a I think it is. What connector style would you recommend in this case? \$\endgroup\$
    – Gimmacus
    Commented Mar 25, 2021 at 15:09
  • \$\begingroup\$ Those pin headers are perfectly fine for four-wire resistance measurements unless you're trying to get hyper-precise measurements of GΩ-scale resistors. When I say signal integrity I'm thinking more of high speed digital communications, or wide-bandwidth analog, anything that needs impedance matching basically. \$\endgroup\$
    – Hearth
    Commented Mar 25, 2021 at 15:12
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Seeing how many compatible connectors are available from different manufacturers and how many are stocked is a good start. There are some connector families that never really go out of style: D-sub, DIN, etc which could be suitable choices, but maybe not all in one connector as you've seen. I would suggest taking a look at the D38999 series III connectors which are milspec so you know they're being produced by more than one manufacturer and probably in good quantity too. The 23-35 (aka H35) insert configuration has 100 size 22D contacts, each capable of carrying 5A. Plugs are about $40, depending on where you look and who's making it.

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  • \$\begingroup\$ I'll have to look around at the connector you mentioned, I see it's a circular connection, in my experience those generally don't have seating issues if screwed on correctly and provide a pretty reliable connection. \$\endgroup\$
    – Gimmacus
    Commented Mar 25, 2021 at 15:03

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