ribbon cable interconnection - 12 way cable mount - Page 1
Forum section: electronics / beginners

author: armandine2
author_rank: Frequent Contributor
timestamp: May 25, 2023, 12:42:57 pm
content: I have, or will have, a 20cm 20 way socket/socket IDC cable.I need to "tap into it" on cables 1-12 to include a switch (as per drawing and instruction - I may include later) .The designer/author has not given further instructions as to how this is done,... but, I assume, a combination of a 12 way cable mount (crimped) male and female connector would work.One connector crimped to the 20 way ribbon and one crimped to a new 12 way ribbon going to the switch (and back).Yet sourcing these pairable cable mount 12-way male/female connectors isnot as easy as I'd assumed.Any thoughts?

author: u666sa
author_rank: Frequent Contributor
timestamp: May 25, 2023, 03:14:20 pm
content: Quote from: armandine2 on May 25, 2023, 12:42:57 pmThe way I understand you is as following: you either need to tap into wire 1 and 12, or wires 1 through 12, on your 20 wire ribbon cable, and you need to install a switch between them. The way I understand your problem is that these two wires or wires 1 through 12 need to be turned on or off.Floppy disk cable has 36 wires, so you can cut it to size. I'd get a socket into which you can plug your original cable, so that you don't have to mutulate it. Into that socket you plug in your new cable, which you'd be mutalating and installing your switch. Then your rigged cable will be plugging into whatever it has to be plugged, either directly or through another socket or adapter. Yea man, you'd need couple of old floppy disk drives, floppy disk cable, a maybe an old motherboard, and an appropriate switch.If it is just wires 1 and 12, then any old switch will do, but if it is 12 wires 1 through 12, then good luck finding an appropriate switch. Possibly finding a switch will be the most challanging and expensive part.

author: mariush
author_rank: Super Contributor
timestamp: May 25, 2023, 03:30:40 pm
content: I don't see the problem, maybe I'm not reading it well?a 20 cm cable 20 way socket/socket idc cable - so like an old ide cable but with 20 wires instead of 40 or 80 wires right?So on each of the first 12 wires, you need to be able to cut the wire and introduce a switch?The easiest would probably be to make small circuit board with one right angle 20 pin female and one right angle 20 pin male connector, and between them, have the pins for the 12 pin male header and then you can decide to either place a jumper across or to put a 2 pin cable or to put the 12 pin connector inside the header.female 20 pin headers :https://www.digikey.com/short/8w2zh7t3male 20 pin headers :https://www.digikey.com/short/zdr21z8z

author: radiolistener
author_rank: Super Contributor
timestamp: May 25, 2023, 05:22:42 pm
content: unless your cable is used for a very low speed digital transfer with a proper buffers, I would not recommend to use any kind of "switch" or interconnection board inside that ribbon cable, because it is usually very sensitive to a characteristic impedance along ribbon cable and RF interference. For example, if it's used for a floppy drive it can lead to a read/write errors. If it's used for HDD drive, then I think it leads to a 100% malfunction.if you're still needs to switch between two devices, then there is needs for some high speed receiver board, which receive data and mux it to a proper output through proper buffer. That's not a simple switch, it will be a digital circuit.

author: armandine2
author_rank: Frequent Contributor
timestamp: May 26, 2023, 06:40:19 am
content: just in case my narrative description didn't fully capture the circuit , see schematic[edited to add picture of 20-way ribbon cable - which I will tap into with a 12-way cable mount connector]

author: armandine2
author_rank: Frequent Contributor
timestamp: May 26, 2023, 10:57:00 am
content: Quote from: u666sa on May 25, 2023, 03:14:20 pmthat was my first thought

author: EPAIII
author_rank: Super Contributor
timestamp: May 27, 2023, 07:03:46 am
content: I have played games with ribbon cable more than once. Your schematic does help some, but there are still a number of questions in my mind.You say 20 conductor ribbon cable. But you do not say what the spacing of the conductors in that cable is. In the US the most common spacing/pitch is 0.050" or 20 conductors per inch. But there are many others, both English measure and metric. So that should be stated. In my projects I almost always used that 0.050" pitch cable.Then you talk about connectors, but do not specify what kind. Again, the most common type, in my experience, is the dual row, header connector with the pins on a 0.1" grid. That type goes well with the 0.050" pitch cable. But again there are many others, both dual row and single row types and with both English and metric pitches.Finally there is the question of conductor and connector pin numbering. Just going back to my experience with the 0.050" pitch cable and two row header connectors with the 0.1" pin spacing, I have seen TWO ways of numbering the pins on the connectors and a third is possible. And it is those pins, not the individual conductors, that are present on the PCBs so the pin numbers are often the numbers that count. But perhaps not completely in this case.The first numbering scheme that I have seen is to number the connector pins to match the ribbon cable's sequence so, on a dual row header connector, all the odd numbers are in one row and all the even numbers are in the other row. They jump back and forth from one side to the other. Thus the pin numbers match the color coding of a rainbow ribbon cable.The other numbering scheme that I have seen is to number them like an IC, starting with pin one in one corner and going down that side with 2, 3, 4, etc. until reaching the other end. Then the remaining numbers are in the other row. But there is still another variation because the second side can start opposite the highest number in the first side (like an IC) OR it can start opposite the #1 pin. It is confusing to use rainbow ribbon cable with these schemes. So that is really three different numbering schemes. And it is important to consider which one is in use.Depending on which numbering scheme is actually in use, the design could go two or three different ways.With my experience with this type of thing, I hesitate to offer any advise until all the details are known. If the wire numbering scheme and connector type is not yet chosen, then perhaps the design could be made to keep those choices simpler. Another possibility is how the signals are assigned to the numbered conductors. Again that assignment can make the design easier or more difficult. Is that fixed or yet to be decided?Another consideration is how this circuit will be used. If it is to be part of a commercial device then precautions should be taken to ensure that the cable and connectors can only be assembled one way. But if it is a prototype, a one-of-a-kind, or to be of limited use by knowledgeable people who are not likely to muck it up, then some other tricks may be employed.PS: The makers of header connectors do make them in almost any number of pins up to 40 or 50, at the least. Well, the dual row ones are only made in even numbers of pins. Places like Mouser and DigiKey in the US will stockallsizes. There must be similar sources in the UK or Europe.Quote from: armandine2 on May 26, 2023, 06:40:19 am

author: armandine2
author_rank: Frequent Contributor
timestamp: May 31, 2023, 12:19:39 pm
content: Quote from: EPAIII on May 27, 2023, 07:03:46 amI believe I have these - and not staggered -- but the RS filters didn't reveal a 12 way male plug to fit my female socket, alas

author: AndyBeez
author_rank: Frequent Contributor
timestamp: May 31, 2023, 03:13:40 pm
content: Most EEs here would place your two-pole four-way push switch onto a small PCB with the 20 way ribbon cable plugging into a 20 way IDC male header (see attached) - sometimes called a 'box header'. The unused 8 pins are not connected (NC) but this maintains maximum mechanical strength and, is easy for someone else in the future to understand. You could fabricate this on stripboard if you have the assembly skills :-)It isconventionthat looking down onto the header with the slot on the left hand side, pin 1 is top left and pin 2 is top right. Pin 1 also corresponds to the red stripe on the cable. So K3 reads 1-2, 3-4, 5-6 ... 19-20

author: armandine2
author_rank: Frequent Contributor
timestamp: June 01, 2023, 06:28:50 am
content: come on Andy - it's a 4 pole 2 throwthe other comment does not make much sense to me either, thanks for trying

author: AndyBeez
author_rank: Frequent Contributor
timestamp: June 01, 2023, 08:15:36 am
content: Try asking on the Arduino forum. Those guys nail it.

author: Ian.M
author_rank: Super Contributor
timestamp: June 01, 2023, 08:33:52 am
content: Andy was basically saying, build it as drawn:i.e. assemble a new 20 way cable, extended to the right of K3 to connect to the switch. He was saying most of us would simply fit a third 20 way female IDC to the cable, and put a male 20 way header on the switch board.If you are tight for space, you could split the extension down to 12 wires, and trim the remaining 8 wires off flush at K3. Doing it without a PCB mount header and soldering wires direct to the switch pins would be an absolute last resort.

author: armandine2
author_rank: Frequent Contributor
timestamp: June 01, 2023, 02:39:04 pm
content: I agree (I think with you) about the third IDC - it can 'tap into' the cable i.e be a cable mount - it could even be 20 way as you suggest and I don't need 8 of the wires. What I don't get is that this can be done as simply otherwise - my only assumption not to piggyback two cables to one connector. The switch header is by the by - I need to get to it first. :'(

author: Ian.M
author_rank: Super Contributor
timestamp: June 01, 2023, 03:07:54 pm
content: You *can* get a male IDC to fit to an existing 0.05" pitch cable, so you could Y off an extra cable to the switch, but they are somewhat uncommon, so you'll only find them at major distributors, and unlike female IDCs, cant be easily crimped in a vice. The extra free-floating M-F connector pair takes up a significant volume so is not an option if space is tight. Also, if you wanted to fit a 12 way one to a 20 way cable, you'd have to split the cable, and have enough slack to get the eight untapped wires clear of the new IDC to do so.N.B. IDC stands for Insulation Displacement Connector so if its not cable mount its not an IDC!

author: armandine2
author_rank: Frequent Contributor
timestamp: July 14, 2023, 07:06:49 pm
content: the 101 female to female practical demonstration - I doubt anyone has uploaded a y-branch / male connection