EEVblog #14 - An unusual oscilloscope phenomenon! 

I discovered the same thing a few years ago! I added a sheet of aluminium foil as an 'antenna' and a peak detector circuit and created a very sensitive motion detector. It was able to display my footsteps as I was walking around the room or waving my arms. It was probably more effective than most infrared motion detection systems! It only worked in 0% humidity though.

*watching it again after 9 years!*

I reproduced the effect with a Tektronix MSO 4104B-L, 1 GHz BW, 5 GS/s. It does take several tries. I leave it waiting for a trigger of 40 mV in single trace mode, and eventually it happens . It also happens on the other 'scope channels which have open/unshorted probes. Thanks Dave. EMI/EMC is a topic of interest.

Before I even started the video I was guessing the the probe was acting as a magnetic B-dot probe, picking up the emi from the static electricity. In my lab, we short probes like this and hang them over the near a Marx generator and look at the trigger waveform for quick on the spot frequency diagnostics. I love these videos though.

Great Scott. This is on my feed a decade later. Finally!! Time travel. See you again in 10 years.

Many years ago in my college lab class I tested an 741 Op Amp with an analog scope and found it had a 'ringing' frequency of ~ 50 MHz

@Picobyte I agree, it is more likely the loop formed at the tip of the probe, not the coax.

Ground loops can cause some really weird things in a radio receiver. In just a 555 oscillator running at audio frequency, if I were to put the ground scope lead to the far right of the power supply and the probe on the far left ground, I can pick up a square wave in the ground plane of my breadboard. Move the scope leads closer together, and the square wave goes away proportionally to the distance between the probe tip and the 555 grounds. A 104 cap to ground on pin 5 didn't affect the output. 10MHz single-trace scope from 1967.

Dave, your videos are fantastic. This is arguably one of the best as it speaks to electrical safety. Hat-tip to you Sir!

Awesome. From the video what i could understood that, when Dave gets up from the chair & touches the floor which is the ground, static charge from his body flows to ground, & due to known phenomenon of inductance probe nearby picks it. And Oscillocope displays it(plus tank circuit concept as explained by Dave). I am not sure if Dave is barefoot or wearing slippers or shoes when he get up from chair & comes in contact of ground. I am beginner so may be i am misunderstood something.

discovered that long long time ago, and much before I decided to give it a try on youtube. But it's fun to watch a video recorded 10-15 years ago, and a video format from that time.

Yes ESD would be worse on a dry day, and could definitely be affected by the fabric type on the chair (not due to the piston though).

I am a technician at AE Techron and we had a customer complaint about glitches seen at the output of our 7224 Amp when being driven by an AE Techron 3110A signal generator. I was noticing that static could cause glitches. or turning on or off other test equipment on my bench. Or some one turning on a microwave . or me standing up quickly out of my chair. I do have a static strap that I use when working on the amp but at that time I just sat down and then stood back up and wow another glitch appeared on the scope. my scope is a Lecroy LT374L which is a 4 ch color 500mHz scope. and I love it. I was also suspecting glitches occuring from air compressor kicking on and or refergerator microwave hot water heater exc. SO I put a very good EMI filter on my scope and that helped. but still not fixed. then I put a 10nF cap between common and ground of the amp and that further helped. Now I can turn on the flourescent lights at my bench without causing a glitch. But if I turn on a HP 33120 signal generator I still get glitch. I wish i would have seen this video earlier this week. I spent most of the week on this problem. Because a customer didnt want to buy our product with these glitches that may occur 1 time per hour if not much is going on.

ill save everyone 9:50 buy simply saying that when u stand up the static discharge creates a small EMP witch momentarily displaces the electrons in the cable creating a small charge wow 10:00 to explain that =\

The resonator is most probably the shorted probe, not the cable, that is a transmission line. The spark that generated the input is oscillatory too.

"I'm trying to bullshit you". Lol that was exactly what I thought at the moment

Now after Your newest video about microphonic - I think maybe the suspention of the chair made vibrations that makes microphonic effect to MLCC caps and that generates voltage, not static?

Is it really the coax picking up that signal? That small ground-wire loop can also act as the antenna.

I filmed a comment that I have seen it happen from several meters away, but it didn't make the final edit due to time constraints.

Love the videos, will love to see more videos on troubleshooting with an oscilloscope

I think It's your chair. I used to field service and had a problem with a user's terminal shutting off. It turned out that the nylon bushing in the chair acted as a static generator. When the person got up off the chair, and the chair rotated, the back of the chair would touch the keyboard of the terminal. The resulting static discharge would shut the terminal off. Note your event happened when you got up from the chair.

You’re basically just creating a simple loop antenna.

(20 years in science...applied one...) YOU ARE AMAZING KEEP ON GOING YOU HAVE REAL TEACHING SKILLS . You make the world better,and future of many young potentials. Thank You For Your Work

Hahahaha you look so young compared to what I'm used to!

My headphones make that noise when I lift off my chair. Very similar profile, dangerous static, sometimes enough to pop the drivers. Usually depends on the foam composition in the chair and the fabric

@Desmaad It's definitely proven to be static, nothing to do with microphonics.

I had a similar experience. The waveform on the scope would move when I waved my hands over the circuit. I found out it was bcoz of the sweater I was wearing. I took it off and what a relief. I am pretty sure, if you are careful with what you wear, you will see less of the glitch.

I tried and could not get anything on my Rigol DS1054Z upgraded. I got some bubble wrap, just to check I could create sme static, rubbed a t-shirt created static that my electroscope loved but my DSO didn't flinch. I don't think my scope has the scope for this.

1:50 So this machine is an all digital scope, and the screen indicates it doesn't use an ORT?

the shape is a sinus cardinalis, the fourier transform of a rectangular signal and since FT works in both ways, there has to be some interesting mathematical background. im trying to figure that out :)

@pugleo Of course it's the static caused by the chair.

That is a hi freq tank circuit. So you have a nice LCR tank. I would think you would almost need a X-tal doping LCR to check some of these scope probes. Maybe my Teague might do it. The best teacher I had was the one my high school retired due to budget cuts. I knew a TV repair shop he worked in was close to home. He also did RTVB work, as well as antique TVs. I was heart broken when they laid him off before classes started. SELL ME A GAUSS METER CHEAP! You must obey! LOL

Hallo Dave, I haven't seen all your 1000+ videos yet, but after watching this video: looks like all these fancy ESD shoes, mattes and hand bracelet's do little, when one's clothes have lot's synthetics. It appears like a wrong fabric or even parts of it can generate enough ESD voltage and accidentally kill one's circuit. What clothes do you suggest to wear when playing with circuits?

Did you know that coax self generates glitches and noise ? Just wiggle a coax connected to a scope turn up the RF intensity the energy in the open space , the scope will indicate the signal NO NEED to stand on a chair.

I think this is a transmission line reflecting back and forth with a loss at each end. I think you should try doubling the length of the cable to half the frequency, and half the cable for double the frequency. If you use the scope 50 ohm term you will termination it will terminate the line for no reflections. If you want a non ESD stimulus try shorting charged capacitor in a near by loop of wire..

Been jumping up and down the last 5 minutes until i've heard the word static. I am in a static free room.. :)

your scope probe is a simple antenna.

Very interesting video now I can show off my knowledge to my friends

Hi Dave, Like your VDO alot. it is down to Earth Oscope dummy like myself. Have you ever thought about producing a VDO of how to use and what to use the O cope to test different/ various pieces of electronics equipment? I will be your first customer to buy them.

cool phenomena, thanks Dave for showing it to us. in the end NERDS RULE!!!

Love the videos. Thank you and keep up the good work.

Could you please make a video titled "What are the things to look for when you purchase an old analog oscilloscope?"

is there an actual 1meg resistor in the input of scopes? 2 significance of the chair -climbing?

btw what is the background sound I hear 9:20 , some small airplane or what, a helicopter? And I just discovered my secret, I watch the video and commenting in the same time so usually, it happens that I leave more than one comment with different time stamps.

i dont think it come from the static of your chair but from the metal tube from your chair moving in the cylinder of the mecanism.

I tried it on my 70MHz digital Tektronix one but it didn't work. Does it have to be 100MHz? What does that even mean anyway?

@EEVblog nice investigation, curious if you can tried generating static manually on a larger scale

Tinfoil between leads creates antenna picking up only alien broadcasts...

Is it the corona discharge that creates the broadband EMI? Very strange. Is it worse on dry days? I has nothing to do with your chair, right? maybe some kind of pseudo-piezoelectric effect from the chair piston thingy?

a Wavelet :-) Nothing is for ever as it is in Fourier. Glitch=Wavelet in this case Mayer or Ingrid Daubechies non-symmetrical wavelet - in a Wavelet spectrum it would appear as a single shot at del.t and "frequency" if one can say that in a Wavelet type spectrum display. Great for displaying "glitch" if the "shape" of the glitch is known. Unlike unrealistic Fourier will work only on continuous sinusoidal that go on for ever - there is your "new" trivia. I like your work keep it going - I am viewing all your blogs as I am impressed with a practical aspects. //Nick

I've read that air core inductors--like your probe cable--can pick up vibrations, known as "microphoning". Have you considered this might be the problem?

Spark gap transmitter.

I figured this out without a scope, my monitors would turn off when I got out of my chair...

body capacitance to scope and lead changes suddenly ...

It might also be that the way you shortcircuit the probe is creating a solenoid (a 1-turn one) loop. Could you try it again shortcircuiting without the loop?

oo-er!! big question....how to stop or reduce it!!!!

The good ol days

Surely the co-ax is capacitative too?

Must take a long time for noise to get to OZ.

Can I use scope for finding of buried wiring using a coil connected to it's probe ?

i think dat input capacitor is the key....noting to do with static electricity ....it can be generated by u hair too...

What is a division? I have had a scope since IO was 12 and I just don't know. I can do advanced mobo repair and troubleshooting. It's my business I own at the age of 21. I can do all this but yet I don't know common terms, pppffftt. embarrassing.

U know what I learned in school? Using this setup to detect RF signals =)

Maybe was not the chair but what was on the chair...

could it possibly be the chair that is causing the static

Why any company who produces a product which is made to be maniuplated (used) by a person constantly (like lots of controls and knobs, such as an oscilloscope) would call their thing "TDS" is beyond me. You say its model number, and it sounds like "tedious!" :-) It's gotta be "Textronix Digital Scope"

Still procrastinating after all this time... he says he will show something and then... sidetrack... then say he’s going to show it... then sidetrack... for ages lol 😂

Dave, what is the inductance of your probe and capicatance at the scope input?

Will this work on any 100MHz scope? Mine is a Rigol DS1104z.

Stop wearing polyester :0) going to try this at work tomorrow.

We've come a long way...

Are you saying "crow probe"?

2020

at 5:50 the answer ...

2019 Buahahhahahahhaha, you were so young! :D (Ops - we were... ;) )

That was a good video

COOL!

Ah you tested that :)

I love your videos, but I would suggest you to make them shorter. I guessed right from the start though. I would make the video only 2 minutes.