EEVblog

Mystery Teardown!
What's got two pads and generates a Devo Energy Helmet waveform?
Forum: www.eevblog.com...
Previous teardown: • EEVblog #909 - Heart D...
Fluke Whitepaper: support.fluke.c...
EEVblog Main Web Site: www.eevblog.com
The 2nd EEVblog Channel: / eevblog2
Support the EEVblog through Patreon!
/ eevblog
EEVblog Amazon Store (Dave gets a cut):
astore.amazon.c...
T-Shirts: teespring.com/s...
💗 Likecoin - Coins for Likes: likecoin.pro/@...

[@EngineeringVignettes]

I have actually designed one of those... The one I made could measure energy of a FRED defib waveform... It came out pretty accurate... Good ol 8051 MCU running it. Cheers, - Eddy

[@98xjdriver]

Yea! That's the item I sent to Dave! I'm glad to see it actually arrived :) Thanks for the teardown.

[@GiddeonFox]

Am I the only one who saw the thumbnail and skipped through the video trying to find the part where Dave tears down a Devo hat

[@mikeselectricstuff]

Insulating sheet looks like Tufnol or similar.

[@ibd1977]

Bakelite

[@GeckonCZ]

We usually call it Pertinax here in Czech, but that's probably just one of many trade names for it...

[@stanilastefan1687]

In Romania we call it Textolit but i think the english name is Textolite. Very good insulator, easy to work with pretty good mechanical strength an heat tolerance.

[@dj_paultuk7052]

Yup, its Tufnol. Used to use loads of the stuff once upon a time. Even machine it on a mill and use it for a modelling material.

[@stevenduhaime1484]

Phenolic, is what we used to call it.

[@bigclivedotcom]

To make a defibrillator fire it would need to see a suitable fibrillation waveform on those metal pads. I'd guess that's what the other chain of resistors is for.

[@ZomB1986]

"My resistance to bullshit is going up" - must be the quote of the day!

[@pwnoobhax]

Transthoracic; Trans-thor-ass-ic Meaning moving through the thoracic cavity (chest). Love seeing medical/scientific devices being taken to bits.

[@eugenekochnieff]

Mate, the scope output is for viewing the defibrillator output not the simulator outputs. The simulator outputs are present on the 5 terminals on top of the unit. these signals are to simulate the patient so the defib can be tested to ensure that is triggers at the correct part of the ECG waveform. Not all defibrillations are for Ventricular Fibrillation, sometimes a patient is fibrillated to correct a non fatal arrhythmias. Also modern automatic Defibrillators can Defib without user input so a tester with an ECG simulator that can simulate both normal sinus rhythm and Ventricular Fibrillation is needed.

[@ptamog]

The strange resistors in the resistor divider should be caps to form a capacitive divider and being able to work at higher frequecies. Hi impedance resistor dividers only work well in DC.

[@aklef]

I smell the clickbait Dave...

[@Yogsoggeth]

It worked too. I never would have clicked on a video called "Defibrillator analyzer teardown"

[@chrisalpha2354]

eevblog along breakfast before going to work.priceless.

[@flymypg]

I wasn't as shocked by this teardown as I expected to be...

[@dummyvariable3079]

BobC Watt else did you expect in a teardown video?

[@leisergeist]

Dummy Variable it's a defib joke presumably

[@ottoreuter6279]

And not a jewel in sight...

[@martinkuliza]

Why? Why not join the Resistance instead

[@flymypg]

OK, I *was* thinking of saying: "Another heart-starting teardown!" or, perhaps: "A smart dummy load?" or maybe even: "I'm confused - Is this for testing AEDs or IEDs?"

[@JonTheBrush]

That sheet looks like phenolic, and will have that lovely hospital smell to it, go on Dave give it the sniff test!

[@vex9060]

The insulation sheet is based on paper layers impregnated with synthetic resin. It's also called paper based laminate!

[@SOCOLVN]

Love Devo

[@keithrefior6990]

IntraThoracic - Through chest. Vent - Ventricular Afibrilation, Back in the day I used one of these all the time. Fluke Phillips went crazy buying up Biomedical test companies after I left Biomed. Enjoyed this teardown a lot... Took me back in time. Thanks Dave.

[@Audio_Simon]

The insulating sheet, as others have said, is phenolic resin bonded cotton woven sheet. Interestingly, it is basically 'Bakelite' and was first used IIRC for aircraft cockpit panels, I think B52.

[@uzaiyaro]

I’m no heart surgeon but the VENT1/VENT2 modes probably simulate ventricular fibrillation or ventricular tachycardia, both somewhat similar conditions where the heart beats rapidly, but inadequately or irregularly. Defibs would likely have a seperate routine to deal with these types of heartbeats, as it would have a seperate routine if it detects a normal heartbeat (don’t fire). I’m likely to be corrected but that’s my theory anyway.

[@EngineeringVignettes]

Yeah, Coarse and fine Ventricular fibrillation, or V.Fib for short. It may also simulate Atrial fibrillation (A.Fib) but unlikely as I do not think that unit can test AEDs (which need to know the difference between A.Fib and V.Fib in order to fire.) - Eddy

[@pyromen321]

Wow great video that I definitely already watched the entirety of!

[@EEVblog]

One day I'm going to add something 2 minutes into a cool video to make it the worst and most offensive video ever, and watch all the early commenters.

[@mzflighter6905]

Gotta love that !!!

[@johnfrancisdoe1563]

This is obviously for testing/calibrating full feature hospital defibrilator carts that are used multiple times per week, not the modern disposable defibrilators that are placed in public and are typically used at most once before replacement. All the 7 connection on top are for the wires that would normally connect to different parts of the patient. The jack on the side would connect to some common device in the maintenance workshop (at the hospital), while the scope should plug into the BNC with a regular 50ohm coax. The rough waveform resolution may be because some of the simulated "events" have much higher amplitude, so the ones you measured are near the bottom of the range.

[@Falcrist]

Dave, I don't think the 8-bit-ness of the DAC is the limitation in that waveform. The vertical divisions are finer at points and coarser at other points, which leads me to believe that the time resolution is what's causing the crazy steps.

[@1337Frost]

I used to build some of the newer Impulse units, I recognized this classic unit immediately!

[@MidnightVisions]

@5:50 That material is called Micarta, similar to fiberglass but a form of linen is used instead of fiberglass.

[@Systemrat2008]

In a past life i worked on defibrillators and the more advanced units also had heart rhythm monitors and it was very common for the US FDA to mandate an update maybe to firmware or hardware so i found myself sitting in an active ER up to my elbows in defibrillator. i one had one that lived in an ambulance returned it's main capacitor had exploded and had a big hole in its side I don't know if it was connect to a patient at the time :-( I also did a stupid thing by putting a sheet of paper between the paddles and letting 300 jewels discharge. it arced through the paper burned a small divot into the stainless steel paddle which cost me most the the afternoon to carefully sand flat again. Sadly I've also had the need to be be connected to a defibrillator a few times to stop and restart my heart. i was sedated at the time but it leaves a nice red burn mark where the pads where.

[@mikeissweet]

Systemrat2008 To stop and restart your heart?

[@Systemrat2008]

Had atrial fibrillation 2 x cardio versions and then an ablation where they put a catheter via a vain in the leg up into the right atrium and burn nerve paths inside the heart. So far that has been successful. en.wikipedia.org/wiki/Atrial_fibrillation en.wikipedia.org/wiki/Catheter_ablation

[@tonyw8001]

So what you're trying to say is you sat on your fat ass ate shit most of your life then expected doctors to help you after self inflicting your problems

[@Systemrat2008]

Idiot - Do some basic research which will support my initial statement. PS I do not have a fat ass. Have a nice day

[@vk3hau]

Systemrat2008 I have WPW syndrome and have to have ablation to, but I'm on the waiting list so take verapamil till then.

[@TzOk]

The insulating sheet is made of textolit (Rezotex). It is very old (known since late '30s) and a common material. It is made of a cotton fibers (also a fiber glass version exits) and a phenol resin. I'm surprised you didn't know it before. Very old PCB were also made of this, but more common usage was a base plate for electric switch/fuse-boxes and also in mechanics for plain bearings.

[@dj_paultuk7052]

That insulation material is called "Tufnol". We used to use it allot in the UK for high energy insulation back in the 80's.

[@Maadhawk]

Looks like fish paper, the red board, but stiffer. At least that is what we called the laminated like orange insulation we used in the Navy.

[@MrTripcore]

I only like mystery teardown when it ends up being something that I want to watch

[@Anamnesia]

"I've never one SO BIG!!!" - That's what she said... 🤣

[@Darkknight512]

You probably did not see an output on your scope at your first testpoint measurement because the amplitude was too low (1 mV), but at the DAC the voltage was higher it seems (500 mV). The second set of resistors is probably the voltage divider for the output from the DAC to whatever device is measuring. Doing this you can also simulate the high output impedence of the body. The large voltage divider probably also protects the DAC from the defibrillator during operation.

[@DJ-Manuel]

Oh, when you are talking about schiller: The company I work for is doing the conventional (THT) component placement and selective soldering of those components on the PCBs‘ of schiller. And I‘m not even from China, so its #swissmade :D xD

[@onlyrgu]

Vent might be referring to icu / ccu ventilator. ventilators have fancy ecgs that can be remotely monitored

[@oldiron1223]

Dave; That fiberglass insulation board is the same thing as was used in old tube radar sets for insulating high voltage, high current power supplies. Really top drawer stuff but expensive. I did know the dielectric rating on the stuff because we would have to test it every 2 years but that's been 30 years back and I just don't remember.

[@RentableSocks]

Dave, that insulation sheet looks like it could be some old school phenolic resin!

[@mikeoliver3254]

Is is a phenolic insulator. It is great stuff, when I was in the US Air Force we used it as clamp blocks for wiring and hydraulic lines in aircraft.

[@OverKillPlusOne]

My aunt works for one of the companies that manufacture the new POU type defibs that get mounted everywhere. Pretty sure they send them back to refurb (replace batteries and test/cal I'd imagine) I can ask her if anyone is interested.

[@vladnickul]

In my country that brown material its called "textolit" , its a a cotton based fiber, infused with fenolitic resins, more names for other flavors are sticlotextolit (cotton fibergalss ) Pertinax Stratitex Sticlostratitex. Used to be the go to material before FR4 in pcbs, but it allso used to be machined, I like it :D

[@glenslick2774]

The analyzer has a Medtronic / Physio-Control asset tag sticker on the front. Their main office is about 5 miles away from me in Redmond, WA. They make Monitor/Defibrillators and AEDs, among other things. Maybe they used this for R&D on some of their products.

[@Michael-1337]

Pretty cool. Most defib units on the market now days have their own built in testing systems. This allows for easy daily self diagnostic test to ensure the unit is working at the proper specifications. Paddles are not used much these days at least in the region where I work. They have been deemed unreliable and it increases risk of coming into contact with the patient when a shock is administered which will put your ass on the floor if your touching the patient when they get shocked and possibly stop your own heart or put you into an unstable rhythm.

[@gustavgnoettgen]

5:50 in tech school we used these glass fiber resin compound sheets for transformer bodies. When you file or drill it its stinks badly from formaldehyde.

[@m.k.8158]

Fluke has bought many companies over the years...for example, they bought the remains of Victoreen, and STILL sell several of their products to this day.

[@furrball]

My guess is vent1 and vent2 would be two forms of ventricular fibrillation. If you tried to scope them, you'd probably see a series of close spikes with no P waves (the smaller spike before what simulates the QRS complex, the P waves being generated by the atrial sinus, the heart's natural pacemaker).

[@PlasmaHH]

A blue pcb from 1990, haven't seen much colour variety back then...

[@shurdi3]

5:40 We call that Текстолит back here in Bulgaria (or textolite in english), really common on older appliances. Usually known as a good insulator

[@hightechstuff2]

I'm surprised to hear you have never seen phenolic sheet before, Dave. Its used in numerous insulation applications however, it was more popular decades ago.

[@randycarter2001]

I wonder, is the actual output of the DAC coming out of the 2 pads? I could see this device simulating a beating heart so that the defibrillator paddles can pick it up and show it on its own display. The stair case is designed to check resolution and bandwidth of the display and make it obvious that it is a test waveform.

[@eddyfontaineyoutu100]

The two types of "resistors" are perhaps a C//R daisy chain to form a high voltage input capacitor ?

[@pepper669]

"My resistance to bullshit has certainly gone up" - ROFL. Dave, maybe you could re-purpose this nice machine as a BS detector :D!

[@muppetpaster]

the brown insulator is called Pertinax.....It smells horrible when cut or drilled.

[@alfredorenteriavillanueva7462]

Mexican viewer over here! I love your videos, mate.

[@T3sl4]

Insulation sheet: garolite, linen phenolic. Old school stuff.

[@dtiydr]

5:50 Bakelite impregnated with some fibers, perhaps glass, have high dielectric resistance.

[@SkyCharger001]

the low-res nature of the test-waveforms may be due to memory constraints... EG "if we make the test-waveforms 4-bits per sample, we'll save ourselves one ROM-chip without actually endangering the reliability of the product."

[@kathyquinlan5922]

Dave, I think the ECG signals should appear on the banana posts, these can hook into the defib so it can analyse and display the ECG signal, so you can see what the heart is doing before, during and post shock (hospital etc defibs have paper chart recorders so they can give a hard copy of an event.

[@thevivekmathema]

That nice piece of technology, Dave. Thanks

[@dhpbear2]

Does this imply that a defibbulator is a constant current source?

[@lesmoor001]

i love your enthusiasm great video

[@awesomeferret]

Hey, I live in Washington, USA too! Hello from Washington State!

[@bluedeath996]

I have one of those model hearts shown at 11 mins. Not sure a defibrillator is going to get it started though.

[@esdblog6100]

What a lovely scope :)

[@pravardhanus]

The brown coloured insulation sheet is "hylam sheet"

[@johncajka5424]

50 ohms is what the pads see when you get zapped so that is why they use 50 ohm load

[@anishsarkar120]

"My resistance to bullshit is going up" ---- should be treated as EEVblog or Daves Quote

[@martijn4740]

nice dave

[@billelkins994]

I suppose the generated waveforms appear on the paddle contacts.

[@1ohtaf1]

That insulating sheet looks like Micarta.

[@pvc988]

14:20 Wow, that's one crappy signal.

[@programmernerd4527]

I watched the entire video waiting for the DEVO part.

[@flatfrog69rr71]

Hi Dave Thanks for the great video Can I ask you a question ? Are you studying for your ham license? It's just you keep making reference to RF terminology and you seem more knowable with RF matters Sorry if I am wrong ! Thanks once again

[@Falcrist]

The new standard for defib testing may have been instituted in 2010. The two standards mentioned in the video appear to have been merged, since the AAMI site calls out DF80 as a previous designation for the 60601 document. From that page: _"AAMI/IEC 60601-2-4 covers the basic safety and essential performance of medical electrical equipment intended to defibrillate the heart by an electrical pulse via electrodes applied either to the patient's skin (external electrodes) or to the exposed heart (internal electrodes). This standard does not apply to implantable defibrillators, remote control defibrillators, external transcutaneous pacemakers, or separate cardiac monitors. This standard amends and supplements IEC 60601-1 (third edition, 2005)."_ Of course these standards seem to be behind paywalls. Unfortunate. :(

[@C2welder]

Micarta is the wood like material

[@Yogsoggeth]

OMG this is made by DYNATECH! That's the South Park company that made Toweleeie! I actually am shocked.

[@SupraBlack-dp4zz]

FYI, the defribillator keeps you alive while you are dying. Literally. When it's time for you to die, the thing keeps shocking your heart to keep it from stopping. It's a terrible site. Not sure if they shut it off now or not, but I've seen somebody who had one and while it was definetly time for the person to pass, the jolting of this unit would not stop. Such a horrible site to watch.

[@m.k.8158]

Actually, you got it backwards(sorta). When the heart goes into Fibrillation, the muscle fibers just fire randomly, so no blood gets pumped....the purpose of a Defibrillator is to stop the heart COMPLETELY, so that it can restart on it's own, hopefully in a proper rhythm. Of course, it does not always work, and not all heart issues cause Fibrillation.

[@SupraBlack-dp4zz]

Ah... Gotcha. I do have it backwards then! Regardless, it was horrible to watch the pain my grandma endured. Unfortunately she passed within minutes after said above happened.

[@supernova86]

Ofcourse Simco calibrated it... they will sticker anything =P

[@jacekpaw1]

Fluke has calibrated this unit because DNI Nevada belongs to Fluke.

[@Sjalvstandighet]

I've just noticed the clock on the oscilloscope... 1:39AM. Dave, do you know that you're supposed to sleep at night? :D

[@powerelectronicsguyl306]

Just a general question about EEVBlog design videos. Why don't you do any high power (kw) circuit designs????????????????? I sent a request on your forum.

[@yakacm]

Haven't watched the video yet, but I'm hoping there is an explanation for the Devo hat thumbnail.

[@ZontiBoy]

Mexican viewer here!

[@KSSilenceAU]

Hi Dave!, I have a Faulty UPS that complains of an inverter over-voltage fault as soon as it tries to bring the inverter online (its a double conversion unit), it would seem to be a silent failure as well, nothing went bang that i know of, and i haven't smelt any magic smoke. Do you reckon its repairable? If i you would like to do a reversible teardown on it and attempt to fix it and make a video on it, i'd be happy to deliver it to you. Model is a Chloride Active RT 3000 Series. i actually have a second nearly identical unit that did go bang, and it was found the inverter mosfets went boom, im gonna try and fix it myself.

[@RedwoodRhiadra]

1:24 wtf, Dave, you turned it on!

[@CPD-KD6-3.7]

I think I'm your only viewer in Mexico, and I'm from Jersey 😹

[@huanhosedubo]

I'm a mexican viewer. Cheers!

[@Samuel-ti7hv]

dummy resistor thats the term im looking for

[@km5405]

when DSS really was 8 bit or less ... those were the days

[@LeLyfa]

WHY did you turn it on before you took it apart???!??

[@tomstern1681]

I won't connect any of my scopes to that thing!

[@SK-dv6yc]

So why is the signal measured from a heartbeat called a sinus, when it doesnt even look like a sinusoidal waveform?

[@zenodorous]

STFN it's nose powered

[@AndrewJones-tj6et]

Yes quaint crusty old school, acres of space socketed PCB's. You didn't sniff test it Dave?

[@VintageSupportServices]

The insulator is phenolic

[@danuber5558]

You're crazy Emett Brown

[@mquintus3681]

you just saved my breakfast :) cheers mate :D

[@w3vjp568]

"Are we not men?" "We are EEVo."

[@synaesthesia2010]

this model goes for as much as $1,250 on ebay

[@picobyte]

@eevblog My sister complained about your voice.I told her not to go to Australië.

[@landonwilliams565]

Hi. Could you do a video on I2C. I like your style and other videos that seem pretty good are not spoken in an accent I can understand..

[@devinblack20]

wow, shocking video

[@pseudotronics]

Dave, I think that is garolite.

[@mbirth]

1:25 … OMG! You turned it on before taking it apart!! That ruined the whole video for me… /s

[@ccish8098]

Fluke bought Dynatech Nevada