Connector help - Page 1
Forum section: electronics / beginners

author: paul23
author_rank: Regular Contributor
timestamp: August 08, 2012, 10:05:25 pm
content: I´m having real trouble trying to work out which type of connectors to use. What I basically need to do is have a connection between 2 PCBs, the cable length is going to be about 10cm. I need 7 lines between the 2 boards, which are all either signal (I2C) or low 12v power (unsure of exact value yet, but definitely way under 0.5A). Ideally it would be best to have the cable fixed to one of the boards and then able to unplug from the other fairly easilyLooking through Mouser, DigiKey, RS and Farnell it´s really confusing what plug connects to what socket and which cable you use with them or they don´t sell the right cable. Am I looking at the wrong suppliers, or just am I missing something?If someone could point me in the right direction, it would be greatly appreciated.

author: David_AVD
author_rank: Super Contributor
timestamp: August 08, 2012, 10:51:43 pm
content: What about standard 0.1" (2.54mm) IDC headers for the pluggable end:The fixed end can use a transition plug:Both of these are used with common 0.05" (1.27mm) ribbon cable.

author: olsenn
author_rank: Frequent Contributor
timestamp: August 08, 2012, 10:52:14 pm
content: You neglect to mention what frequency your signals will communicate on, but by the sounds of it, it is most likely quite low; in which case you should be able to get away with just about anything. At under half an amp of current in 10cm of wire, you're not going to have to worry about the internal wire resistance or disipating too much power through it.As for which to chose; there's plenty of options. A standard ribbon cable connecting to IDC headers may be all you need. If you need something more exotic; for instance thinner, sturdier, cheaper, better looking, or easier to connect/disconnect, there are many options available to you. You may wish to even consider connectors that were meant for something else entirely; say for instance a USB 3.0 connector.Hope this helps

author: mariush
author_rank: Super Contributor
timestamp: August 09, 2012, 01:46:03 am
content: Like David said, those cables should be enough. They can handle the current and signals you need.If you want to go crazy, rj45 network connectors would work :http://www.digikey.com/product-detail/en/5555153-1/A31438-ND/769582Or repurpose a usb 3 cable... connectors are readily available:http://www.digikey.com/product-detail/en/1932258-1/A101494-ND/2618533

author: notsob
author_rank: Frequent Contributor
timestamp: August 09, 2012, 02:10:02 am
content: AS a general idea of what is available, have a look at some of the connectors these dudes in the UK stock, as you are outside of the UK don't bother buying from them, [very expensive shipping outside of UK]

author: paul23
author_rank: Regular Contributor
timestamp: August 09, 2012, 07:19:14 am
content: Quote from: David_AVD on August 08, 2012, 10:51:43 pmThat´s exactly what I was looking for but didn´t know they were called IDC headers, so couldn´t find anything like that. Thanks, I will search again now I know what they are called.Thanks everyone for your help.

author: ciccio
author_rank: Frequent Contributor
timestamp: August 09, 2012, 08:10:02 am
content: I second David_AVD suggestion: "flat cable" IDC type connector are, for small runs, the most efficient type, because you can assemble a cable with an inexpensive tool (less than 30 euros) or even without a dedicated tool (a small bench vise can do the job) and you don't need to buy dedicated, expensive crimping tools.Other advantage: crimped contacts sometime require exact wire gauges, that sometimes are not available in small quantities. "flat" cables and connectors from different manufacturers are in effect interchangeable.Best regards

author: David_AVD
author_rank: Super Contributor
timestamp: August 09, 2012, 10:43:25 am
content: Yep, those IDC connectors and cable are common and cheap. Why use some esoteric connector for a simple task?

author: paul23
author_rank: Regular Contributor
timestamp: August 09, 2012, 11:12:05 am
content: Searching for IDC connectors got me exactly what I needed. I did need to go up to a 10 way connector though, 7 or 8 way were harder to find. I can use 10 though without problem.Any recommendations for the tool to make the connectors? There seems to be a few at different prices. Does it it really matter for low volume, say a couple of hundred connectors?Thanks again.

author: ciccio
author_rank: Frequent Contributor
timestamp: August 09, 2012, 11:36:05 am
content: I use, for small lots, this Chinese tool :http://www.marcucci.it/prodotti/schede/scheda.asp?ID=970.It is cheap (15 euros + VAT) and works reasonably well. It can also crimp the 9 to 25 pins "D" type to Flat cable connectors.After a long search on the printed catalog (RS website is totally un-friendly and un-useful), I've found it is also available from RS : code 235-6428 (price in Italy is 16.99 euros + VAT)Best regards

author: paul23
author_rank: Regular Contributor
timestamp: August 09, 2012, 08:03:53 pm
content: Grazie, They are the same ones I was looking at and wasn´t sure if they would do the job. They are more expensive in the Spanish RS site though.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: August 09, 2012, 11:31:21 pm
content: You can get them from ebay too, starting from $20 incl shippinghttp://www.ebay.com/sch/i.html?_nkw=ribbon+cable+crimp+tool&_sacat=0&_odkw=ribbon+cable+crimper&_osacat=0But, as pointed out earlier, you can also use a small vice to crimp them. Only important feature that you need is a parallel squeezing action.

author: Rufus
author_rank: Super Contributor
timestamp: August 10, 2012, 12:52:05 am
content: Quote from: Short Circuit on August 09, 2012, 11:31:21 pmWith care a small vice works fine. For transition and DIL headers with pins 3 bits of 0.1" strip board glued together gives you a spacer with holes to accommodate the pins.

author: David_AVD
author_rank: Super Contributor
timestamp: August 10, 2012, 01:48:43 am
content: You can also probably use a spare cable crimp female connector to hold the male transition connector during crimping. (assuming you're using the 0.1" row pitch versions)