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I have completed a few projects - sensors and an ADC circuit - and I find myself often connecting discrete boards together by tediously soldering wires to break-away headers like those below.

I worry about poor connections and the time it takes is excessive.

What are some good, flexible go-to prototyping connectors? I am considering getting some RJ45 connectors and using old cat 5 cable, but they aren't 0.1" spacing friendly, which makes prototyping with them harder. (Do 0.1" compatible RJ45 connectors exist? Could I rig these up anyway?)

I realize this is highly dependent on the application but I was hoping to get a solution for the general case. Or maybe soldering ribbon cable to headers is the way to go.

For a little more information, my current projects have involved carrying a ~2v signal ~1m to an ADC, carrying 1MHz SPI ~0.5m between an ADC and a PI, as well as carrying around 3-5V power and ground - so nothing terribly fancy.

Update: I went with IDC connectors (2x5 pin and 2x20 pin) and I am happy with this decision.

enter image description here

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closed as primarily opinion-based by JRE, Andy aka, Wesley Lee, uint128_t, ThreePhaseEel Feb 19 '17 at 13:44

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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Why solder the wires to the header pins when you can use flat cable with IDC connectors?

No soldering at all, compatible with 0.1 inch spacing, and the cable and connectors are easy to assemble (and cheap as well).

[Flat cable with IDC connectors]

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  • \$\begingroup\$ I think this is the winner. Thanks for saving me from myself. Cat5 when I need robust signal wire. \$\endgroup\$ – nate Feb 19 '17 at 1:06
  • \$\begingroup\$ Definitely the correct choice for me. \$\endgroup\$ – nate Mar 20 '17 at 1:12
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When I have room for 0.1" connectors, I almost always use the KK-style connecters from Molex:

molexkk

They are relatively cheap, have different pin configurations, and (importantly) have been considered "bin stock" in every lab I've worked in. Also, if you choose the connectors with "locking ramps" (as shown), these ensure that you won't plug it in backwards, and also keep things from disconnecting accidentally.

You'll have to buy a crimper, but you'll use it for years. A Molex-branded crimper will cost you a few hundred USD, and high-quality generic ones can be had for $20-30 on Amazon.

I'm currently using this crimper. I bought it because it's cheap (currently $23), and I was pleasantly surprised at it's quality. It hasn't failed me yet.

Another benefit is that you can choose connectors for different wire sizes.

Here is an answer I posted about using this type of crimper.


To answer your other question, I just ran into this at futurlec.com:

rj45proto

I've never done business with them, so I can't speak to their quality. But these adapters are currently selling for $2.90, so it's hard to go wrong :)

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  • \$\begingroup\$ One issue I have found with these is that if you try and use them with solderless breadboards then when you try and unplug the cable you tend to end up pulling the socket out of the breadboard instead. I have resorted to superglue in the past to get around this. \$\endgroup\$ – Peter Green Feb 18 '17 at 0:42
  • \$\begingroup\$ @PeterGreen Yeah, that's true! And the header pins seem to stretch out the connections in solderless breadboards, too. Maybe it's because I buy cheap breadboards :) \$\endgroup\$ – bitsmack Feb 18 '17 at 0:47
  • \$\begingroup\$ Thanks for the link, Im going to grab some of those break out RJ45s \$\endgroup\$ – nate Feb 19 '17 at 1:10
  • \$\begingroup\$ I have bought from futurlec before, and you get exactly what you see. If not stated otherwise, I'd asume lead solder, but their breakouts and other parts are fine quality for prototyping (and the price is right) \$\endgroup\$ – Extrarius Feb 20 '17 at 4:08
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For boards that already contain pin headers (like in the picture you provided), I tend to use connectors that mate into the existing headers - similar to this Harwin M20 connector. They're available in a lot of different positions (e.g. 1, 2, 5, 8 pins and even double rows), which is convenient when having to connect to pins that are not adjacent. You have to buy the pin contacts separately, as well as a pin crimping tool. But this approach has saved me a ton of time and effort trying to solder wires directly to these headers (and the cables can be re-used for other projects once you're done with the current one).

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In addition to ribbon cables with IDC connectors (as mentioned by Enric Blanco), you can buy individual 'jumper wires' with female connectors (ex Here) on each end that are compatible with the kind of pins you posted. I've used them to great effect when there are many pins to connect but they're not in a similar layout (eg connecting the gpio+power on an FPGA board to an LCD board). If you use a breadboard, you can also get similar jumper wires with female connectors on one end and male on the other to be able to wire from pins to the breadboard, and male on both ends for use on the breadboard.

If you want something like RJ45 that are prototype-friendly, you can get breakout boards from many places - ex RJ45 MagJack Breakout or RJ45 Adapter

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