name & function of this component cover? (RF shield?)

[Adam Funk]

I was taking a piece of scrap equipment (old cable modem, I think)
apart just to see what was in it, & noticed two perforated removable
cases around some of the components.

Photos:
http://www.ducksburg.com/diy/20130323-electronic0.jpg
http://www.ducksburg.com/diy/20130323-electronic1.jpg

I suspect the cases are grounded but perforated to allow airflow but
shield the contents from radio interference --- is that right?

What are they called?

 

[Tom Biasi]

I was taking a piece of scrap equipment (old cable modem, I think)
apart just to see what was in it, & noticed two perforated removable
cases around some of the components.

Photos:
http://www.ducksburg.com/diy/20130323-electronic0.jpg
http://www.ducksburg.com/diy/20130323-electronic1.jpg

I suspect the cases are grounded but perforated to allow airflow but
shield the contents from radio interference --- is that right?

What are they called?

Sounds like you know what they are.

 

[Adam Funk]

Sounds like you know what they are.

Well, it's nice to get it confirmed.

 

[Adam Funk]

Doghouses. That's not their formal name but it is what we call 'em.

Thanks! What would they be called in a catalogue (for example)?

 

[Tom Biasi]

Thanks! What would they be called in a catalogue (for example)?

RF shield, but most are made to meet a particular design.

 

[Michael Black]

Sounds like you know what they are.

"The perforated whatchamacallits".

It almost sounds like a trick question, that somehow there should be
something more than "shielding".

Michael

 

[Michael Black]

Thanks! What would they be called in a catalogue (for example)?

It'a not an off the shelf piece. A design is conjured up, it's layed out,
and then that defines the size needed, so it's off to the machine shop to
make the shielding. Obviously it's mass produced in commercial equipment,
but since it's to fit the circuit, it's made for that circuit.

If you were doing it at home, you'd get a metal bending break and bend
some thin brass or whatever thin metal you could get cheap. Tin cans
would offer up small pieces of metal that would work. Or someone else
might solder bits of copper circuit board together to make small shielded
compartments, again especially useful since you can make them to the size
you need. If you weren't up to that, you'd buy miniboxes (now often too
big) to build up isolated stages in.

Or dig through the junk pile until you find something that is the right
size. Older (and thus larger) IF transformers were once a source, once
transistors came along. Copper pipe might be used, with end caps. I find
myself often saving those bits of shielding from commercial equipment
because they can make neat boxes for this. Anything that offers up a
small box of about the right size is useful, though less likely to be
found in today's electronic equipment.

Michael

 

[Phil Allison]

"Adam Funk"

I was taking a piece of scrap equipment (old cable modem, I think)
apart just to see what was in it, & noticed two perforated removable
cases around some of the components.

Photos:
http://www.ducksburg.com/diy/20130323-electronic0.jpg
http://www.ducksburg.com/diy/20130323-electronic1.jpg

I suspect the cases are grounded but perforated to allow airflow but
shield the contents from radio interference --- is that right?

** RF shielding is certainly the purpose - but the other way around.

Those ICs inside generate RFI that could upset services like TV or Wi-Fi so
the shielded box is to keep it in.

What are they called?

** The material is typically tin plated steel.

So tin boxes will do.

You see the same in most TV sets, VCRs and FM tuners - housing the tuner
itself.


.... Phil

 

[Adam Funk]

"The perforated whatchamacallits".

It almost sounds like a trick question, that somehow there should be
something more than "shielding".

Good one! Thanks, everybody.

 

[Adam Funk]

"Adam Funk"


** RF shielding is certainly the purpose - but the other way around.

Those ICs inside generate RFI that could upset services like TV or Wi-Fi so
the shielded box is to keep it in.

Interesting, thanks.

 

[George Herold]

I have a bunch of those.  They're pretty nice, actually.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot nethttp://electrooptical.net

We get some things like that from leader tech.
http://www.leadertechinc.com/
I've just used the 'fencing' without the top... that was enough to
stop capacitive feedback in a high gain amp.
It all seems way over priced to me. I seem to recall ~$25 for a 2"x2"
fencing and top.

I also buy stuff from these guys,
http://www.orbel.com/

A little PCB shield 100 for ~$4 each. It was cheaper to design the
circuit to fit under the shield than making a custom shield.

George H.

 

[Fred Abse]

If it weren't for British English, you'd all be speaking French.

In the days of the Founding Fathers, American English *was* British
English. They subsequently diverged.

 

[Michael Black]

"screening can" has been in common usage for some time.

I can't say I've heard that one before, but it works.

After all, people have called "IF transformers" "IF cans" and obviously
the "can" is in reference to the shield, not the actual transformer
inside.

Michael

 

[Fred Abse]

We saved your asses remember - Hitler was about to drop dirty nukes all
along your eastern Seaboard.

Cite references.

What decided the outcome of WWI was US industrial might, enabling the
Allies to fight simultaneously on four fronts.

I cannot understand why some, fortunately few, Brits,instead of expressing
gratitude, indulge in criticism or derision, at every opportunity.

 

[Fred Abse]

Remember what they said about the GIs: "Over paid, over sexed, and over here."

I'd have said that the British soldier was underpaid. Something to do with
the class system.