#2042

[@ToumalRakesh]

As my HF Professor used to say: "Never look into the open end of a pipe. Either someone's flushing the toilet, or there's microwaves coming out."

[@scottsmith5048]

Nice Faraday cages, I suspect that fan should be mount on the outside of the cage.

[@humidbeing]

When you do shielding for EMP protection for military gear we have to use copper tape on all the tiny seams. EMP are very broadband and even tiny pinholes let too much energy in.

[@bobkozlarekwa2sqq59]

Great video. A few topics come to mind. First, the material that the box is made of aluminum versus brass versus copper versus nickel . I’ve made several enclosures using un etched copper circuit board, and soldering the joints together. Second a company in Connecticut called Miller. Stevenson makes a conductive nickel spray dries to a rough sand like finish. I’ve used two coats over the surface of a small plastic box with great results.

[@SkyhawkSteve]

Yep, I've made RF enclosures (for test items) with copper-clad circuit board too. Solder the sides to the bottom to seal it up. Might use copper tape to seal the top to the sides. It's not as clean as a machined aluminum enclosure, but it's certainly quick and cheap!

[@ats89117]

Jim Williams was famous for using heavy gauge tin plated cookie tins because they provided better shielding especially at lower frequencies. Henry Ott preferred paint cans. This is one area where spending a lot of money doesn't buy much if any improvement...

[@EssArrB]

Yes, the old style cookie tins are tin plated steel which attenuate magnetic fields as well. Nowhere near as good as mu-metal or other soft magnetic material but if you need better attenuation you can always put one tim plate box inside another. At AF I often get magnetic field junk, usually transformers radiating 50/60Hz and lots of harmonics, the cookie tins work wonders to get rid of it. Shame all the cookiecandy assortments we used to get at xmas are all plastic tubs these days.

[@androgenoide]

I worked inside of a screen room for a few years and my impression is that a single layer cage doesn't always provide enough attenuation. The screen room was essentially a box within a box with a layer of insulation between them.

[@Grateful.For.Everything]

Damn, what was goin on inside that room lol, 2 screens will do the trick is what I’m getting, which is good to know because maybe that’s what it takes to reach real silence.

[@YSoreil]

Such a strong faradey cage it even absorbed the episode number

[@return2sender791]

😆

[@Elias-f4h]

Cookie tins from 'dollar tree' / 'family dollar' or 'dollar general' are around a buck and similar sizes to your thousand $ machined lunacy for prototyping. 1" sheilding tape or copper tape to seal the edges can easily get 140dB E field (NO holes). You might want to look up slot loaded antenae at microwave freqs. One thing to be aware of - reflected internal resonances can be nasty above VHF, sooo some sort of lossy material inside to break up standing waves. Smallest box necessary is best. Cheap $59 microwave from Walmart or Amazon is also quite good to GHz (typically > 80dB). Home document fire safe are cheap, too. Second outer box as double magnetic shield for 60Hz out of soft steel (old file cabinet etc). ...been there, done that And incidentally, MIT is a bunch of crazy folk: They invented card counting. One group of students made a 'licking' machine to test Tootsie Pops - you'll never forget this now if you RF.... 377 licks 377ohm free space 😎

[@iainmcculloch5807]

I was wondering if the sheet is Eccosorb GDS? I foresee some fun experimenting in your future. 🙂

[@sachiperez]

my tinfoil hat keeps me connected! Great video topic for a Faraday!

[@byronwatkins2565]

A fine-wire spring also makes a great rf grommet/gasket... compressed about 2%-5%.

[@davidv1289]

I recently put together a 19 Gigaohm resistor inside a copper enclosure that connects to a guard potential and is in turn housed in a metal box that is grounded. This was used to test an electrometer I was repairing. It worked well, eliminating almost all outside interference. Regards, David

[@erwe1054]

1 резистор 100 гигаом стоил 75 долларов я позвонил в компанию и мне прислали готовый

[@louiskatzclay]

I had a friend who had a business that wove conductive gaskets. Sometimes they used silver wire, sometimes copper, sometimes gold. Some of his gaskets were used on airplanes, others in microwave ovens, rockets,,,,,

[@humidbeing]

Those same spongy conductive pieces were also commonly used in desktop computers and laptops in the 90s/00s

[@samreames1713]

Same problem here and I made mine using a square Christmas cookies tin. Nice idea using SMA. I used BNC and terminal jacks for power inputs for mine so the power leads can still act as an antenna. Always room for improvement depending on how deep you want to get into it.

[@PlaceholderforBjorn]

The Tinfoil hat story really got me! 😂 But I have thought about making a cage out of a used microwave. As those I don't really know how much they attenuate, but should be quite much as you cook your food at ~700W. But maybe you brake the seal if you drill a panel mounted coax connector to the Inside.

[@IMSAIGuy]

kzbin.info/www/bejne/sJmknp6HfKeDpposi=6vTE5Xs7pIEcI7Fy

[@allthegearnoidea6752]

Have you ever used box vented with mesh with a depth close to the noise source frequency. The cavity creates standing waves, so you can still have a screened box with a hole cut in it. HP used this for some of there test gear

[@KeritechElectronics]

A nice and elegantly built box.

[@TheTrueCBaer]

I've read there is foam that you stick into such boxes, maybe under the lid. It's resistive and dampens down unintentional cavity resonators. Maybe that's was the sticky stuff is

[@therealjammit]

About the peel and stick ferrite. I wonder if those flexible fridge magnets would work?

[@THEELECTRICGUY]

2:50 It would be great if you can share the paper link.

[@alanknight7867]

Hi I used some of the foam covered in wire mesh many many years ago . I must have got from RS or Farnell ( in the UK ) as thats where I got most of the stuff I used at work . If it was a Vero product your out of luck as they no longer exist . Alan

[@StianEklund]

Interesting video. I recently built a RS232 sniffer / splitter and lined the box with copper tape but it's not perfect in that it doesn't cover the entire inside of the box. I realize I've basically created a capacitor, although it might not be a problem it might also be less resistent to RF than without it perhaps? 😅

[@charlesdorval394]

Wow, that material is very interesting! I've been looking at shielding some analog stuff I'm working on lately, I would have totally tried the tinfoil, thanks for the heads up, I don't have any instrument capable of telling me sadly

[@chrisharper2658]

I few decades ago, I had some of that RF absorbing sheet material. I thought it would be really cool to line the inside of a front bumper cover to see if it would make a car invisible to radar. I wonder if anyone ever did that? I used a lot phosphor bronze for RF shielding because if it's springy nature and that gasket material that feels like a cat's tong. It's silicone but with tiny wires oriented in one direction. And yes, aluminum foil generally makes things worse. Any overlap becomes a slot and that's all it takes. I guess it must be because aluminum oxidized so easily.

[@byterock]

Egad you are entering your 'Tin Hat' years ;) That would be great video yes indeed

[@robinbrowne5419]

I think that stuff is the same stuff they make fridge magnets out of.

[@rahulkushwaha9500]

good friend. it would be interesting to see that rubber ferrite thing in action.

[@humidbeing]

The "grommet" material is just conductive ground foam/tape found all the time in 90s/00s desktop computers and laptops. Usually stuck to the metal outer case panels.

[@AdmiralQuality]

I saw some stuff like that in a computer display I recently disassembled for connecting the board's ground plane to the light's. Spongy but metallic.

[@leetucker9938]

I have to re design my government secrecy helmet now

[@romancharak3675]

What extraordinary boxes! AND what will we do without our "tin-foil" hats? Oh no!

[@jspencerg]

So, one needs to drag a grounding strap off their foil hat. That's inconvenient!

[@SkippiiKai]

I'm much more interested to see you measure noise with the test circuit OUTSIDE the box and your LED supply in it than the other way around.

[@paulperano9236]

Wonder if the antistatic foam used for ICs would work for an RF grommet ?

[@Elias-f4h]

No

[@dave_dennis]

If you find sources for the ferrite mat and grommets please post here.

[@jman51]

I can’t believe that these cheap LED bulbs and integrated switched mode power supplies can be sold when they radiate so much energy

[@SkippiiKai]

I think he said he made it himself in a previous video.

[@charlesdorval394]

Ah, good ol' i²c, neat! Noted on the tinfoil hat, I'll share the knowledge lol

[@andymouse]

Well you did ok there as those boxes would have cost a few quid for sure !

[@DavidGillooly]

I just must find that MIT paper on the failure of Tin Hats!!!!

[@VovelPunch]

wow

[@BkR090]

Is the grommet what is missing in the tin foil box? It reminds me of Dave Jones's light box. Interesting.

[@Chris_Grossman]

Eccosorb

[@AdmiralQuality]

Gasket, not grommet. :)

[@galileo_rs]

There must be a few hundred bucks of gold plating on those boxes considering the current price of gold.

[@AdmiralQuality]

It's only a few atoms thick. Almost nothing. Literally pennies worth. (The application treatment costs more than pennies but the value of the gold is only a small part of it.)

[@galileo_rs]

@@AdmiralQuality Back in those days they did much thicker coating. For example on the, now infamous (among gold recyclers), Pentium pro CPU they used up 0.3g.

[@AdmiralQuality]

@@galileo_rs Well, it depends on the application, I guess. And .3g of gold is only $25 USD.

[@Elias-f4h]

There was $30 in gold recycled from my old Tek 7000 scope, ASICs and connectors.

[@AdmiralQuality]

@@Elias-f4h Is that before or after energy costs? :)

[@alanvandusen76]

I have some of the mat from Spectrum Microwave, not sure if they are still around. But it is part number 21109145 or PN 700-17164-0001. Good luck finding a data sheet.

[@Mr.Leeroy]

1:50 all you need was cookie tin can 🤏as per Linear Tech ApNote 159 - Measuring 2nV/√Hz Noise and 120dB Supply Rejection on Linear Regulators

[@6AK5W-JAN]

Where are you buying your cookie tins that they come with a copper box inside and a mu-metal box inside the copper box?