EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: bd139 on December 03, 2018, 10:53:21 am
-
Does anyone know any brands / part numbers for stiff stranded ribbon cable? I can find lots of floppy stuff but I want to use some for panel / inter-board wiring in the transceiver I am building.
Tektronix used the stuff in their kit from the 1970s / 1980s but I can't seem to find it or anything equivalent anywhere. It had the interesting property of staying exactly where you put it.
-
Are you looking for standard 50mil pitch stuff? We have some 3M 3801 and 3365 (If there's a difference between the two I can't tell what it is) that's fairly stiff, and can be lightly creased to get reasonable bends. If you were in the US I'd offer to send you some since we don't really use it anymore, but shipping it to the UK is probably prohibitive.
-
Does anyone know any brands / part numbers for stiff stranded ribbon cable?
Do you mean ribbon cable with solid wires? 3M has 3749 with 25mil pitch.
-
How come you want the stiff one? I thought it was a complete pain in the ass and I see them fail (for instance APC power supply). But theirs is almost springy.
I am curious why you would prefer to use it, unless its teflon or some kind of really tough insulation with special properties. I always thought it might be bad for vibration and I would recommend securing it anyway.
Maybe I am not thinking of the same thing as you. Do you mean the rainbow cables? They seem to hold to folds and stuff ( I have seen it in high end IFR equipment). I don't think its stiff but it is malleable. Is your definition of floppy a computer IDE cable, a SATA cable or even worse one of those really floppy connectors you might find in modern appliances (i.e. induction stove).
-
Thanks for the replies both - appreciated.
This is all internal cabling. It has to be relatively rugged and not flop around inside the device as it’s portable. Solid cables tend to stay put and you can tie them down easier in bundles. Floppy is same as IDE cables. If you have three to four strands of the stuff stuff it stays in straight lines as an example.
I tried normal 3M stuff as specified and it is too flexible. IFR kit stuff is about right. I’ve been using some old tek cable but I’m running out of that now.
-
It has to be relatively rugged and not flop around inside the device as it’s portable.
Using such cable in a portable device is a sure way to failure.
-
If its portable and rugged then use flexible cables and secure them with something like this IMO
https://www.newark.com/panduit/lpfcm22-a-c14/cable-fastener/dp/84F1428 (https://www.newark.com/panduit/lpfcm22-a-c14/cable-fastener/dp/84F1428)
It's nicely chamfured too so you can get a really low profile.
And unless the connector has a really secure lock on it, put a bead of sillsastic to seal it in when its done (make it so you can cut through it with a razor blade carefully to fix).
-
Would this line of cables work for your requirements?
https://www.molex.com/molex/products/family?key=tempflex_hybrid_ribbon_cable&channel=products&chanName=family&pageTitle=Introduction&parentKey=tempflex (https://www.molex.com/molex/products/family?key=tempflex_hybrid_ribbon_cable&channel=products&chanName=family&pageTitle=Introduction&parentKey=tempflex)
-
does anyone know of guidelines for ribbon cables being secured for vibration resistance?
-
I have found that some of the rainbow coloured stuff is significantly stiffer than the normal grey. Still probably not what you want though.
-
Devil's advocate position:
Floppy is better.
Consider: it doesn't take up strain, and is more flexible (more range of motion for less fatigue) than the stiff stuff.
It's easier to secure onto walls. Which is really what you want to do. Don't give it a chance to fatigue in the first place!
Explanation of fatigue: many metals have no fatigue limit, meaning, for some degree of strain (deformation), there will always be a point of failure, though it may take some unbelievable number like 10^14 cycles for it to finally fracture. Therefore, less strain is better.
For a spring, force (stress in the material) is proportional to strain. Therefore, more force resulting from a given strain means more risk of fatigue.
("Aha!", you will say, as this is the critical part: the amount of force depends on how much material is in that spring. Whether this line of argument is actually true, depends on the geometry. It may well not be! :) )
As for securing, anything will do: wire ties (hard to keep flat; more than good enough if you curl the cable into a round, assuming it can be routed that way and the greater line-to-line coupling isn't an issue), double-stick tape (3M VHB foam tape is exquisite), clips or other mechanical features to strain-relief or trap or clamp the cable, etc.
Tim