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I'm familiar with pin headers, but I have trouble finding a connector type where a 4-lead connector can fit through a 4 mm round hole.

The standard pin headers with a pitch of 2 mm and 2.54 mm are too large, a 2x2 pin connector has a diagonal larger than 4 mm.

The next smallest type, 1.27 mm, would barely fit through and might get stuck in the 4 mm hole.

The next smallest type, 1 mm, would fit, but I couldn't find long enough male pins to reach the top of the casing my PCB is inserted in (pin headers of larger sizes have plenty of "double decker" variants)

So my question is, are there any other connector types (possibly) unrelated to pin headers, which could fit through a 4 mm round hole?

Notes:

To not make this into an X-Y problem, here is my original problem I would like to solve: A central device is connected to multiple smaller devices, to each with a 4-lead connection (5 V, very few mA). I would like to find a connector, so that for example the male is soldered to the PCB of the central unit, and the females are soldered on cables which are coming from the smaller external devices (or the other way around, with the females on the PCB). However, each cable, with the connector mounted on it, has to fit through a 4 mm diameter round hole, this hole is not on or near the central device. The ideal solution would be for the cables to be plugged into the top of the central unit, this is why I considered a "double decker" pin header, with appropriate square holes on the top of the casing.

long male on board

A much less optimal solution would be to have holes on the side of the casing, so the pin headers or sockets on the PCB would be angled 90°.

90degrees on board

This is when I started thinking: maybe there are completely different connector types which I never heard about, which would solve my problem much better.

I though of audio jacks, there exist some in 4-lead variants, but the plastic casing is much thicker. Also, they are expensive compared with the pin strips.

the problem with most very thin multi-leaded connectors (used in laptop computers, for example), is that although they are very thin, they are also very wide, they are not designed to fit through round holes.

vsz
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    Really stupid question from me: Why 4mm round holes? – JRE Sep 09 '15 at 15:44
  • @JRE: this is a design criteria due to the nature of the device, outside of my jurisdiction. I could have made the question simpler, just to ask thin enough connectors, actually the main question would be what other connector types exist besides pin strips which are small enough, but I though presenting the original problem would be more helpful. If it bothers you, I could simplify the question into a general "What other types of connections exists besides pin hearers, which can fit through small holes", but then a lot of people would ask clarifying questions about the rest of the design. – vsz Sep 09 '15 at 15:48
  • Look here for a similar question if you think this is off topic> http://electronics.stackexchange.com/questions/23695/suggestions-for-small-and-handy-connector-for-in-circuit-programming – vsz Sep 09 '15 at 15:49
  • I just wondered at needing to put 4 connectors through a 4mm round hole. The 4mm round seemed like an odd thing. I didn't mean you should leave it out, I just wondered why. – JRE Sep 09 '15 at 15:52
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    I don't know who voted to close, nor why. This looks OK to me, as you are not asking for a product recommendation but rather a type of product. – JRE Sep 09 '15 at 15:54
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    The reason is because there is a wall (or a wooden panel, etc.) between the central unit and the small devices, and the 4 mm round hole was made due to "aesthetic design" choices. – vsz Sep 09 '15 at 15:54
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    Ah aesthetics versus practicality - use two round holes. – Andy aka Sep 09 '15 at 16:57
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    They make 2.5mm dia 4 terminal headphone plugs as well I think. http://www.showmecables.com/product/2-5mm-Jack-TRRS-Connector-Plastic.aspx has a socket for a wire tail. – KalleMP Sep 09 '15 at 17:06
  • I think @KalleMP's suggestion is quite a good one, 4pin headphone jacks would work nicely. It is possible to get female 4-pin jacks which would fit a 4mm diameter mount hole - e.g. PJ210B (If found one on eBay, but will let you look them up/find suitable part). – Tom Carpenter Sep 09 '15 at 21:35
  • What are the 4 wires? If you have 2 power and 2 data, it might be worth adding a few extra parts and effort to multiplex the data onto the power and then be able to use a normal 2 pin header. – bigjosh Sep 15 '15 at 21:04
  • @bigjosh : there are 4 wires because they are already multiplexed. – vsz Sep 16 '15 at 04:14
  • Again, trying to avoid X-Y, can we ask what is on the 4 conductors? – bigjosh Sep 16 '15 at 13:42

1 Answers1

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As KelleMP mentions you probably could use a 4 pole 3.5mm jack and socket to fit through the 4mm hole with 4 connections.

HighInBC
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