EEVblog - 2019-02-07
How to make your own magnetic H-field EMC probe out of semi-rigid coax for $10 that performs identically to a $300 commercial probe! Search for "Low noise amplifier" and "semi-rigid rg402" on ebay. Forum: http://www.eevblog.com/forum/blog/eevblog-1178-build-a-$10-diy-emc-probe/ Bitcoin Donations: 38y7DE8HEHNj8fGDtUr4PkCn9nWxiorvvy Litecoin: ML7oQokTwB38bgzzjLDbRV97HKAHuwRfHA Ethereum: 0x11AceA38DCA9DbFfB4F35f3F746af65F9dED28ce EEVblog Main Web Site: http://www.eevblog.com The 2nd EEVblog Channel: http://www.youtube.com/EEVblog2 Support the EEVblog through Patreon! http://www.patreon.com/eevblog AliExpress Affiliate: http://s.click.aliexpress.com/e/c2LRpe8g Buy anything through that link and Dave gets a commission at no cost to you. Stuff I recommend: https://kit.com/EEVblog/ Donate With Bitcoin & Other Crypto Currencies! https://www.eevblog.com/crypto-currency/ T-Shirts: http://teespring.com/stores/eevblog Likecoin – Coins for Likes: https://likecoin.pro/@eevblog/dil9/hcq3
One of the best videos in a while!
Totally agree .. high quality content .. stick it to the fat cats Dave .. maybe build a differential probe next from Ebay parts .. there are a ton of broke engineers and hobbyists out there
Yes sir. An RF probe came to mind from an old set of computer external speakers... that'd be about as cost effective. SDR ideas don't seem bad for cheap spectrum analyzers especially if there is an oscilloscope plugin... though I've figured a set of attenuators for the range and profiling the SDR well to know its range of performance to characterize the limitations so you don't blow it up. Probably a current limiting input thingamajiggy too. Normalizer dohicky would be impressive. Least that's what comes to mind. I was also wondering about making a leveling head for the cheapo signal generators since they're so cost effective. Trips me out how cheap some of the modules are and how like this detailed video demonstrates using the hardline or rigid or I guess it's called semi-rigid cable... can be used to make decent kit alone basically or with a or some modules. So much, I just ordered a range of modules, plus some, to make an Antenna Analyzer or looks like is going to be a VNA using Erik's latest modularized version he notes on the SoftwareControlledHamRadio groups.io post on Analyzer Comparison since seems impressive: https://github.com/erikkaashoek/Tapr-VNA
This post, the high voltage probe and the isolation probe video's of EEVBlog are coming to mind as impressive also. I'm sure there's more I haven't seen yet. It's like man jewelry... I buy the components and it looks so great just hanging there even if I hardly use.
Agreed!
@midnightman011 Agree with that.
I'm looking forward to next video "Build a $100 DIY Spectrum Analyzer" <3
you could use an RTL dongle and get it running with SDRsharp or other software for about $25.
It might not be $10, but the W7ZOI homebrew SA was a good design/project from the '90's, rebooted here:
http://hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html
I have done that (500 MHz) , is a lot of work, by the time it was finished I had a few real SA's. http://www.pa4tim.nl/?p=1643 , it is a while back so the page is in Dutch, newer projects etc are in English.
Great, now I just need a Spectrum analyzer :|
Yeah about $20 for the RTL SDR + Spektrum (free)
https://www.rtl-sdr.com/poor-mans-spectrum-analyzer-with-an-rtl-sdr-and-noise-source/
@Samuel Comeau Install it with Pothosware. Dead easy.
Try this homebrew project from a great RF designer:
http://hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html
My $200 Keysight scope has FFT.
SDRplay radio now has some software called RSP Spectrum Analyser by Steve Andrew https://www.sdrplay.com/spectrum-analyser/
TomTekTest has a nice set of videos on this software hardware combo https://www.youtube.com/watch?v=h8-9a6CNyB8
The SDRplay RSP1A can be had for around $100
You had time to build it to scale and to paint it!!!
Only two coats!
@EEVblog I believe this would do a better job coating it than the spray-can version: https://www.amazon.com/Performix-11602-6-075815116024-Plasti-Dip/dp/B000ZN1T16/ref=sr_1_9?keywords=plastidip&qid=1549645102&sr=8-9
The guys at tekbox spent houndres of hours on r&d for this thing to work properly.
Dave botches something together in 10 minutes and it works just as fine if not better than the pro kit. :D
R&D, or D&M (design & marketing)? :P
Research & Development
Getting those curves that are individual, and that are a true reflection on the device, as opposed to lucky try and it worked. Plus the whole repeatable manufacture thing that means you can interchange probes, and not have to run a calibration on each new one you get, just use the curve supplied, which is well within a specified tolerance spread.
That coax looks like they just dipped normal braided shielding and dipped it in some solder.
That is exactly what they did.
Omg that's exactly what it looks like! I have some junk solder and some coax. Looks like my cost just dropped $5
Thats how many places make semi-rigid in the smaller coax styles. Very common.
Need more of these typ of videos
Dave, you need an x-ray machine. Just saying :-)
@EEVblog How to make your own x-ray machine with Cody's refined Uranium that performs identically to a $300 000 commercial X-Ray machine!
no mikes electric stuff
@EEVblog finding the CCD detectors new machines use would be interesting.
I'm detector curious btw.
That's what X-ray technician friends are for. Or a dentist shop.
There's bound to be one in the dumpster from heaven
It's funny that I don't have any use for the probe but found it so entertaining.
*semi-rigid. You can't bend rigid coax without destroying it
@EEVblog This cable is actually called "conformable" coax cable. Meant to be shaped for final application, but not for repeated flexing/bending. Good video. Thanks!
Yes you can. Like a plumber. Just not by hand.
Martin Krehl Yeah you could even bend it by hand if you're careful and keep your bend radius large enough. You could use a 10mm pipe/rod/drillbit shaft and bend it around there for example.. Depends on how big it is obviously, you're not gonna bend the 50mm (or so) stuff at the TV station
Rigid coax often use air dielectric. If you bend them, you will change the impedance and risk the inner conductor touching the outer conductor.
There are specific L-pieces for rigid coax, but often they are custom made anyway (soldered/welded). Rigid is really not meant to be bent.
Dave has a nice video from a TV transmitter site where they had rigid coax pipes.
Antoine Roquentin Well yes and no, you're right on air dielectric on the bigger rigid coax but the smaller ones inside spectrum analysers and other RF gear are all bend from the factory. Generally no L connectors on there. You do mess them up when you rebend them but they get bend into shape at the factory I think
Demonitized by Tekbox.
love all your videos, but i have a preference on EMC/EMI things, keep it up
Seems to me that Tekbox is not at all pleased with this video :-)
we've always called that soldered braid stuff "semi-rigid" coax. Solid copper outer shield was called "rigid" ..
Yes, it's semi-rigid.
Actually the right term for this stuff is "handflex." Examples of semi-rigid coax would include the 0.086" and 0.141" cables with the solid tinned-copper shield that you see in commercial spectrum analyzers and other RF gear. It is not meant to be formed by hand and often breaks when you try.
BOBBY DAZZLER!!!!! NOW I JUST NEED A SPECTRUM ANALIZER..$2000...DOWE!!!!
But the $300 one looks so skuukum! I'd still up for the tenner though. Good job Dave
skookum as frig!
Hum ..... somebody's been watching AVE.
That's the thing, if you are doing it for curiosity, and will probably only use it once, $10 is the go.
Great video Dave! Could you do a similar frequency domain analysis with an oscilloscope's FFT? Just to make it a lot cheaper and accesible, since it's a more common tool.
I would love a video on using FFT function to make these measurements. I think building one of these probes would be a lot of fun for $10. A spectrum analyzer is out of the question for me, and probably a lot of hobbyist, but I do got a scope with FFT.
You could potentially use fft on a scope, if you had a scope with 1+Ghz bandwith. A new 1Ghz scope is in the $10k vicinity. A hacked to 3.2Ghz Siglent spectrum analyzer is about $1700. A HackRF SDR is about $250, and I believe with the correct firmware sweeps 6Ghz rapidly. The lower cost devices would not be calibrated or have features like like tracking generator, so the hacked spectrum analyzer has some significant attractions. There are also PC based vector network analyzers, which add a lot of additional functionality, as they measure phase shift in addition to amplitude. A full duplex SDR + a ebay reflection bridge might be a usable vna with the right software.
Are the 2 thumbs down from the CEO and Marketing Director at Tekbox ? Lol. Tekbox are so overpriced for what they are.
Now start mass production and sell it on Ebay for $50 and bundle it with calibration certificate "Calibrated by Dave".
A cal cert on a post-it note...
Steve Irwin of the electronic jungle.
Is it possible to get any sort of useful reading with a scope? I've seen these used for locating dead ICs
Great video! This is the kind of content that I really like, this is definitely worth the patreon subscription.
Frigging amazing hack! Everyone is going to build one. Thank you Dave, really
Please do a Rogowski Current Probe next!
Great video as always, Dave. We’re dealing with an EMC issue on a project right now..
I think you might be slightly wrong about the commercial probe coating. I feel like they did a grippy gritty transparent conformal coating to help adhesion of the blue shmoo.
Possibly
@EEVblog, would a probe like this work on picking up the signal on an automotive ignition coil, like the coil on plug units. I have seen pickups made for such, but if I can make my own, that would be awesome.
Well, that came in handy! Things ordered, now the waiting begins. Thanks a lot!
Looking forward to the E-field probe.
That was ace, enjoyed that. I was thinking u could 3D print a mould for the coating.
That piece of coax is beautiful.
Interesting Dave, Cheers bud :-)
Awesome video, I like how you show that doing EMI measurements is easy. And in my electronics courses they said I'd never do that unless I go to university, yeah... Right.
Dave thank you for this video really useful video so many applications, looking forward to an official diy PCB.
Really great video, Dave. Thanks!! I know you might not like the request but since we are looking into bargain field probes....what options do we have out there for bargain spectrum analysers? Does Hantek offer anything? Something for the home hobbyist or person at home looking to tinker around or EE student looking to learn more practical application wise about fields. A DIY probe and amp set coupled with a bargain analyzer would be right powerful bit of kit for people like myself.
Great video! Waiting for Part 2 with a little EMI pre-testing howto!
Thanks again Dave. Way cheaper and super easy. You’re the man!!! Gonna build my own.
Fascinating! Thank you!
Oh, nice. I saw the other EMC video and was thinking about 3d printing something and winding the head with the various reels of magnet wire I have here. I also have lots of rigid coax so winner, winner chicken dinner.
I came here to say this is one of your best videos in a while and am amazed to see how many others are saying the same thing. I couldn't believe you peeled back that Tekbox cover; thanks for doing that!
Excellent! Thank you Dave. Videos like this are why I subscribe to EEVblog.
Good job Dave!
Just another grand Video!
Very educative and interesting!
Keep it up! Good onya Dave :)
*dreams of slapping a 9V PP3 on it- dashed *
@eevblog I’m just finding out about these probes. For vintage electronics would there be an application for these? Maybe probing around a TV set to see if certain wave forms are present at components?
That's the kinds of videos we are here for. Thank you!
Great video Dave! The blue coating on the outside of the TekBox probes is likely a low-pressure overmold, which is the same material used on strain reliefs for cables, etc.
In my book, this is a proper tear down.
Great work.
Brilliant dialogue, very entertaining and informative. Many thanks for sharing
Love the enthusiasm. How about doing the E field probe next ?
Das Kässpätzle - 2019-02-07
Now build a additional spectrum analyzer for 10 bucks and every one is happy ;-)
InsideOfMyOwnMind - 2019-02-23
@Chris Balfour Annoyingly I also bought a HackRF and while it is kind of a fun toy at the end it's a POS.
Chris Balfour - 2019-02-23
@InsideOfMyOwnMind If even that's a POS, then it's definitely cheaper to just get an actual spectrum analyzer. Thanks, that's good to know.
InsideOfMyOwnMind - 2019-02-23
@Chris Balfour The thing is, it's rx performance is crap even compared to the rtl. The front end both rx and tx are extremely ESD sensitive. If you touch the antenna without grounding yourself first you will pop it 100% of the time. That said, it's easy and cheap to fix when that happens but what a pain in the first place.
jcbarros71 - 2019-04-25
Most DSO scopes this days have FFT, so at least in the scope BW range this probes can be used to "sniff"
Muck2014 - 2020-08-25
Well, use an old transistorized radio.