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Cost of shielded ribbon cable....use metal enclosures instead?

Flyback

Well-Known Member
Hi,
I am seeing phenominal price differences between unshielded and shielded 10 way ribbon cable.......

**Unshielded 10 way ribbon cable = £1 per metre

**Shielded 10 way ribbon cable = £18 per metre

£1 per metre VS £18 per metre!!!

Would i be correct in saying that this is the reason why people put electronics systems comprising multiple SMPS's, multiple PCBs, and multiple Board to board ribbon cables, into Metal overall enclosures?....ie, because then you dont have to shield all the ribbon cables etc.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
If you use balanced or at least ground interleaved connections in the ribbon, the RFI should be minimised.
And you can get ferrite clamps for ribbon cable to reduce it further.

I think the price of screened types is a result of it not being used much, rather than the other way around. There is not enough market for real competition, unlike with basic ribbon.

"Twist and flat" type is an intermediate compromise that can also reduce emissions, as long as it's used properly.

That is far cheaper than screened, though not as cheap as unscreened. If you eg. get 50 way and split it down to five runs of ten way, it makes it about £2 per metre.

Note that cable screening alone will not help much anyway, if there is more than one possible current path between units.
Each cable must have its own good return paths, then adding a ferrite sleeve restricts unbalanced currents via different paths and so radiation.
 

Flyback

Well-Known Member
Each cable must have its own good return paths, then adding a ferrite sleeve restricts unbalanced currents via different paths and so radiation.
Thanks, it sounds like we need to just bite the bullet and put it all in a metal enclosure?
 

Flyback

Well-Known Member
Thnaks, but no, it hasnt. There are many cables including many ribbons...to have interleaved ground with everything would take too much room. We havent yet added ferrite sleeves no.
 

unclejed613

Well-Known Member
Most Helpful Member
you could buy appropriate sized copper braid ground strap. open up the inside of it, and run the ribbon cable inside it. because of the way it's made, it's actually a hollow tube, even though it lays flat on the spool it comes on.
 

gophert

Well-Known Member
Most Helpful Member
aluminum boxes are getting pretty cheap in recent years. Also, Thixomolded magnesium alloy is getting more snd more common if it is a high volume item that can cover the cost of a mold. With Mg-molding, you can mold any heat sinks right into the housing.
 

gophert

Well-Known Member
Most Helpful Member
You can paint the plastic enclosure with metal paint.
Metallic paint is not generally electrically conductive - a requirement for shielding. Only a few companies make silver pigment ink/paint and it is more expensive than a tin box.
 

gophert

Well-Known Member
Most Helpful Member
gophert

Metalic paint is for cars. Metal or conductive paint is for shielding.


I should have used the term "conductive paint" and a reference. Sorry,
I know. The particular product you show has no datasheet, no shielding response information (thickness vs attenuation vs frequency and saturation limit. In other words, thus product is a lot like "oxygen free " copper wire claims - it sounds cleaner, less humm, blah, blah.
Now, look for a real product with a real datasheet and the price goes up by 5x. Also, you'll realize from their datasheets that shielding efficiency at 50/60Hz is quite low vs kHz and MHz signals so the StuMac products claim of reduced humm is rather funny. Maybe measurable on a scope but your ear will not notice. If you have a claim that indicates the product works, then why don't they have a datasheet?
 

unclejed613

Well-Known Member
Most Helpful Member

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