EEVblog

It's all fun and games until an innocent opamp gets hurt!
Dave proves he's not the sharpest tool in the shed by killing an opamp in his µCurrent calibration test jig, whilst checking the calibration of course.
Doh.
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[@GeorgeGraves]

It's always a fun game when your ordering parts to guess how many spares you'll need!!! "Hmmm, I need one, but I'll order 3, one to blow up doing something stupid and learn my lesson. Another one to re-learn that same lesson. And the last one to get the job done"

[@NickT6630]

I always order more parts because I'm more concerned about parts being discontinued. And this is also why I am soo careful and check everything before applying power to a circuit these days. I remember frying a 741 opamp when I was first starting out in electronics and also the TDA2030 power amp which has no short circuit protection and self destructs with lots of smoke and burning the casing away to reveal its glowing hot IC inside. I built my first amplifier with that.

[@hottokatrazi]

Every good electronics engineer makes this kind discovery during his career. Congratulation, you invented the SED ( Smoke Emitting Diode)

[@engineeredlifeform]

I remember destroying an OP Amp when I was doing my 'O' level electronics project at school. I'd custom etched the circuit board, soldered all the components and chip holder in place, put the OP Amp in, hooked it up to the bench supply, there was a snap noise, something hit me in the forehead, then that unmistakable smell. In my haste, I'd put the 741 in the wrong way around. DOH! We lived in a rural area, and this was pre-Internet, so I had to mail order another. Rushing doesn't get stuff done faster.

[@clairsmyers3571]

I blew a 741 that I was using as a voltage comparator In a battery charger circuit. I was powering it with a 9 volt battery and just momentary touched it in reverse accidentally and the chip was gone. One diode could have prevented this. We learn from our mistakes I hope! lol!

[@Bubu567]

I have about a dozen bread boards with burns on the middle from op amp accidents.

[@FranLab]

Great Scott! Classic Doc Brown moment Dave.

[@sebastianschmidt566]

I wonder how many circuits would survive if their designers understand the concepts of "using a fuse" :-)

[@babybearkill1]

We all have that oops moment in life, no biggy

[@sebastianschmidt566]

BBK1 and sometimes its a sort of "oops I dit it again" moment :-)

[@computergarage-australia2301]

+BBK1 I agree, we all make mistakes

[@SyedRizvii]

Would be great to see a video on good input protection practices...!!

[@SteinErikDahle]

Yes, great idea!

[@metalmishap]

Always wear a condom.

[@NoajmIsMyName]

He did explain it there, kzbin.info/www/bejne/sIbLn3qmatubbJI

[@StevenKiberton]

This goes to show that even those with a lot of knowledge can even do things wrong. We are all human and that is the key flaw in most life events... (human error)... Keep up the great work Dave.

[@robertcalkjr.8325]

"Don't turn it on - burn it apart". lol

[@MTTT-bl2uo]

One thing I learned pretty quickly: thou shalt always connect a dummy load. Powering up an RF power amplifier without connecting a dummy load is fine as long as you're not applying any RF input, right? Wrong! Instability in the amplifier caused it to self-oscillate and lack of dummy load at the output = POP! Now I never ever ever power up any RF amplifier without first connecting a dummy load, even if I'm just applying DC to check bias levels.

[@frollard]

It's excellent to be reminded everyone makes a mistake from time to time. I recently let the magic smoke out of a teensy by probing it with a voltage rail when I thought it was a ground probe (pulling input pins down to trigger the interrupts...The input pullups didn't like being externally overvolted :S)

[@reggiebacci]

Yeah it's comforting to know even Dave screws up. I went through a phase of destroying 7805s by connecting the output pin to what should've been the input voltage. I did about 3 in a row, in the space of an hour, through a comedy of various errors.

[@dasdew2]

In your own words Dave "That's how you learn electronics, you fail and you learn" It's just a learning experience.

[@Xmetalfanx]

same exact thing I tell people curious about Linux ... A) Back anything important up B) When stuff does go wrong ... take it as a learning experience :) ... thats how I've learned alot of what I have over the years

[@alcesmir]

Xmetal Having backups is just good practice overall. Although you can screw things up easily if you want to in Linux, no denying that. I mean you're literally a command away from wrecking all your partitions if you really wanted to and had the know-how.

[@Xmetalfanx]

while of course there is an "up to a point" level of just being silly (and alot of times I am talking to home users) .... "YOU CAN NEVER HAVE TOO MANY BACKUPS"

[@batteryanalyser1729]

G'day Dave. I have not seen this video yet when I decided that going forward all op-amps in my experimental boards will be sitting on a IC sokets to not being bothered with replacement if I cook them. Did not burn any yet. Hard to beleive you did. Voltages at my place are 140-400 V DC. :) and I cooked Mosfets (op-amps were not hurt) couple of times when have not been bothered to run the circuit via Analyser which detects ubnormal current / voltage and cuts it off if mistake was made. Keep up the good work. Another reminder - attention to details is of paramount importance when you are dealing with electricity / electronics.

[@CynicalFlame]

I love how half the time I have no idea what dave is going on about, and still don't really understand the micro current thing, but I am learning! and maybe one day I can watch one of daves videos and understand everything! :)

[@dwDragon88]

"No opamps were harmed in the production of this....oh wait....damn......"

[@nickguy6820]

In this short video, Dave invents the NopAmp.

[@JeffBarberDigideus]

Dave, I'm an amateur electronics hobbiest. I do wiring in Guitars and have some experience of infrastructure and cabling for IT and AV applications, and I just wanted you to know that as a direct consequence of watching your videos, I have managed to expand my interest to fixing equipment to component level. I just successfully diagnosed and repaired a faulty guitar pedal by watching your video on killing Opamps. Thankfully I haven't killed mine, and found the diode protecting the 9v supply has blown open. I just wanted you to know. Many thanks dude, and keep up the great work!

[@AmazingDX]

This reminds me when as a child plugged my gameboy color to one of those universal transformers, the gbc needs 3v and the adaptor was on 12v... poof went the poor machine.

[@blueslayer99]

Any chance we can get a video on how you would go about protecting the inputs to prevent this from happening?

[@ethanpoole3443]

Add some input resistance -- this is a high impedance Op-amp input so you could very likely get away with 1K, 10K, or even greater, input resistors -- to limit the maximum current that can flow into the input when the protection diodes activate. Then, on the Op-amp side of those resistors, add a reverse biased Zener diode. If you use a 5.1V Zener then the maximum voltage the Op-amp will ever see on its input, with proper polarity, is about 5.1V and if you should accidentally inject a reverse polarity on the input then the Zener will limit that to a maximum of about -0.5-0.6V. If you want better reverse polarity protection then supplement the Zener with an additional Schottky diode (in parallel), which would limit the maximum reverse polarity voltage to no more than about -0.25-0.45V. In that setup the Zener will limit maximum proper polarity on the input and the Schottky will limit maximum reverse polarity on the input. Regardless, the Op-amp is now protected from any remotely reasonable voltage mishaps and now has full ESD protection on its high impedance input as well. If you know in advance that 1V is the maximum the input will ever see in normal use then one might opt instead for a 3.3V Zener.

[@iamdarkyoshi]

Did the magic blue smoke escape? If not, it should have worked despite a 60 ohm input impedance... How long did this take for you to realize that the voltage was 10v and the opamp has popped?

[@8180634]

When you mounted the new chip, what was the main reason you used an iron instead of some flux and the hot air to reflow it?

Great talk as always! Nice video Dave.

[@wattage]

Thanks for sharing the head-smacker moment, Dave. Great reminder. Nice to see the ol' meter and soldering iron! Bring 'em out more often.

[@annieworroll4373]

A couple days ago I was probing my op amp with my old crappy multimeter, it's got a long bit of exposed metal and it turns out shorting pins to other pins is not a great idea. The replacement, I put in backwards. Both let out the magic smoke with large cracks in the package, the first audibly popped. The third one held up. Thankfully my EEVBlog BM325 has the probe sleeves so I don't have to expose the entire lead if my use case doesn't actually require that, and the old one can be set aside as a backup.

[@KrzyInuYasha]

LoL, I sorta did the same last night to my Naze32 flight controller. I mixed up my battery sensor and buzzer lines and put 15v from a 1800mah LiPo into a 3.3v 150ma rail. Luckily all I did was wipe out a BAT54C SOT23 double diode and a SOT23 1AM transistor, replaced them (yay scrap boards) and all seems fine so far.

[@giulienk]

It was actually really instructive Dave! I blew up an op amp a couple weeks ago (and it took me hours to figure out that was the part that was not working in the circuit) and I was wondering why and this might well be the reason.

[@slinkytreekreeper]

Maybe a video on what steps would be advised to 'ruggedize' the device to higher voltages and reverse polarities would be worth the effort? I would certainly appreciate an experienced opinion here.

[@dmottern1952]

Showed this to my electronics class. Great lesson!!!!

[@Willam_J]

It takes a humble man to admit his mistakes. As engineers, it's hard for us to admit when we're wrong. When we do, however, it shows others our integrity.

[@MatthewSuffidy]

Recently I replaced all my 60watt lights with CFLs and I have these glass globes on the ceiling here and there. I noticed one died after being on for a day, and took it down to look at it. So what I think is the problem was that they are not supposed to be in enclosed fixtures, and were cooking the electronics or a thermal fuse. So what I decided to do was leave one of the two lights out of each of them and hope it would lower the temperature adequately. I took apart the dead screwy light and got out the little electronic thing to play with but I don't expect to do anything with it.

[@cemx86]

I forget what the multi-turn pots on your board are designed to do but I assume calibration of some sort - which isn't to be changed, right? I cannot tell if they have some anti-tamper paint (i.e. fingernail polish) on these pots. Is there? Should there be?

[@RealationGames]

That moment when you realize that your build isn't working and you notice that the IC is rapidly getting burning hot. Damnit.

[@CH_Pechiar]

Dave, can you comment on the current source you put together? Thnks, CH

[@megatech1966]

I hope you can help me. I have a Logitech Z906 Sound Speaker System for my Windows Computer and retro computers. My Amiga 1200 has blown its op amp twice and the guys on my Amiga forum says it could be my sound system. They said check for AC and DC voltage on the line inputs. I did the other day and it was 24 volts ac. Today it’s 5 to 10 volts AC. I have sent my motherboard away to get fixed. Could that be the reason it keeps on blowing up the op amp? Is that voltage not normal? Is my speaker system faulty? Can I do a easy fix? Or can I take it to a technician to get fixed (I live in Adelaide South Australia) Any help would be greatly appreciated.

[@PilchPlays]

Thanks for your honesty and cander on these sort of FUBAR moments. Its a great learning experience for all.

[@theonlyari]

A video on rail clamping and other input protection would be good. If you had just spent 25c on some diodes you could have saved you $1 part. Thats 75c you could have saved! I mean you could probably get a can of Coke for that-- maybe :(

[@CoolJosh3k]

Mistakes are bad, but these quick informative videos I do like. Thank you for sharing.

[@PTNLemay]

I've started studying electronics at college and my teacher pointed out to me that the multimeter I've been using is woefully inaccurate (I was getting 10-11 V or so from a 12 V source). Are there well known, reputable multimeters out there? I don't want to spend a ridiculous amount on one but I figure if I'm going to start doing this semi-professionally, I'd like some professional tools.

[@gordonkeller6998]

Recently had a good OpAmp cooker scenario. I had just finished a 2kHz, square wave IRLED signal detection circuit that I was pretty proud of and spent all night soldering when a friend asked me to demonstrate the range for him. Despite there being reverse-voltage protection and a voltage regulator integrated into the circuit, I instantly fried the circuit when I set the perfboard down on a solder mask positioning plate without thinking (pretty much bypassing all of the protection)! And I figured that the OpAmps would be first to go, so I replaced them, but no luck. I went through the trouble of testing each capacitor only to find out that it WAS one of the OpAmps after a second switch-out. So butt!

[@johnrickard8512]

Would I be wrong to suggest a schottky diode across the input terminals?

[@shmehfleh3115]

I learned an important lesson recently: Never trust what it says on the outside of the power brick. I wanted to build an LED table lamp out of a cheap camp lantern, so I salvaged the LED & controller. I connected them to a 6v DC power brick, because the lamp was designed to run on 4 D cells in series. Well, it certainly did light up when I switched it on. But then the IC on the board got very hot, and the LED briefly became extremely bright before releasing its magic smoke and dying. I checked the power brick on the meter and was much chagrined to find out it wasn't putting out 6 volts; it was putting out 12. Ouch!

[@Erik-yw9kj]

Moral of the story: check it before you wreck it, maybe? =P

[@tad2021]

There's always time to do it right the second time

[@scott55246]

TAD2020 Or third :)

[@userPrehistoricman]

"check urself b4 u rek urself?" - a happy precision voltage supply

[@djkelectrical]

I'm surprised you've used pots on your test jig. Is it a reliable solution for a piece of test equipment when you consider that it's handled so much? Sometimes when I've set them to a value I feel like I only have to blow on them to create drift or maybe that's because I use WHL branded ones?

[@sarowie]

I would be highly skeptical about the temperature coefficient. But to be honest: In his use case, an out of spec test jig is just a hazard, not a problem. With his Vishay resistors, most uCurrents will be in spec. If the test jig goes out of spec or dodgy, it will - more likely then not - cause a larger number of uCurrents to be flagged as "out of spec" and he will get called by his assembler. Even when doubting it: Calibrating it before giving it to the assembler and recalibrating it when getting it backs. Note: Calibrating is just checking the test jig. Turning on trimmers is NOT calibrating, it is adjusting. Many people mix up does therms, but it is important to know, that calibrating is just checking without touching trimmers or any thing.

[@s_s-g4d]

yeah i figured it would be a good idea to add an input series resistance and clamping zeners regardless of whether i'm going to feed voltage higher than allowed to the input port of the device that i am designing. because i know i will, one day, even though i'm not expecting to. same goes about reverse polarity.

[@fred123864]

Mr Dave, what temp do you set your hot air gun to when removing SMT parts?

[@JasonOlshefsky]

Good on you for letting us know you make mistakes too! My take-away from similar experiences is to desperately, desperately try to _make good habits_. Probably number one is "never rush" which is easier said-than-done-a good 75% of my blunders are due to trying to do something too fast. "Use checklists" is a good one too.

[@KlemenZhivko]

You could explain voltage limiter circuit. Would that be possible?

[@Uterr]

So, how do you protect of this sort of problems? I am amateur in electronics and when i do some stuff whit opamps, i just add 500Omh resistor either to Vcc and to inputs, i don't know is it bad and is it spoils something in scheme? i just afraid to damage opamp :)

[@Uterr]

***** So, i putting this 500 Omh resistors to cut current, if i connect something wrong way. I thought its current that killing it?

[@necessaryevil8615]

A wise man once told us here on youtube how to learn electronics: "FAIL" was his advice...

[@rubber20021]

Your right binding post was for 3mm down!

[@OrbiterElectronics]

If I don't do something like this at least every month or two something is seriously wrong :)

[@Crytek1337]

Your videos are awesome! Dont stop with posting videos!

[@MrBuck295]

Funny thing ,while I was watching this there was a pop up about opamp tutorial maybe Dave should watch and get a refresher about opamp`s lol :)

[@PilotPlater]

Always learn more from breaking something than keeping everything working perfectly all the time.

[@proluxelectronics7419]

Isn't the reference voltage output current limited?

[@BUNCHofxs]

I haven't been keeping up with your vids but it looks like you got a new camera, and a damn good one to...

[@nutin2new547]

Thanks for sharing Dave, good to know even the masters flub sometimes!

[@ABaumstumpf]

At least nothing happened to your regular equipment - albeit unlikely, that would have been a bit more than just annoying.

[@SixthyGTi]

WhenI was in highschool, my colleague hooked up 220 AC instead of 12 DC while I was trying to figure out what's wrong with car audio headunit. Luckily we're still alive... :D

[@michaelhawthorne8696]

DOH ! That was a big ass iron to solder that sot there Dave !

[@Jalae]

why is this not a blab?

[@EEVblog]

Kehnin Dyer Could have been I guess, but Blabs are technically single take rant videos that don't require editing etc.

[@supersat]

Kehnin Dyer Just think of it as an old-school EEVblog video, when KZbin limited you to 10 minutes,

[@rich1051414]

Dunno about anyone else, but if I am designing an op amp circuit for personal use, i grab 3 of them. One extra in case it arrives dead, and one more for when I blow the ass out of it by mistake :)

[@zx8401ztv]

Poor little Op Amp :-(, hope you gave it a honorable burial dave :D Big chunky zenna diode across the terminals?

[@jerrythefisherman94]

This reminds me of when I was in school for electronics. We were taking a test using 741's. We are supposed to apply DC before applying AC. Well, I forgot the DC and fed in the AC. Well, the 741 turned colors and was fried.

[@superdau]

So this wasn't a latchup? Because that really lets some smoke out if you have a power supply with no current limit. I put a capacitor that was still charged with a few volts (maybe around 10 because it was used as decoupling cap just before) on the input of an opamp supplied with +-5V. Imagine my surprise when fire came out ot the opamp on my breadboard and left a few charred holes on there.

[@network_king]

I knew someone they bought a bakery. Got some fancy industrial coffee pot he plugged it in went up in smoke fried like a $550 board. Called an electrician and I guess it was a high leg delta setup.

[@magicphysicsdude]

Huh. I thought inputting a voltage beyond the supply rail voltage would simply cause clipping (and then cause distortion if the input is an audio signal). Maybe there's a different effect for AC and DC inputs. That reminds me, I should make an op amp tester one of these days. Whenever a circuit with an op amp doesn't work for me, I'm always paranoid I killed it.

[@Nordic_Mechanic]

As an engineer, you are allowed to break anything that you can fix :D

[@evahle]

We all have Homer Simpson moments. lol. I knocked out a breaker for half the department in electronics school, while showing a really neat circuit that I built. How embarrassing for an A student!!!

[@tonyinfraredstamp2159]

We've all done it Dave, don't worry mate,lucky it was a quick fix 😊

[@jpopelish]

I think you are pushing that opamp a bit, just by powering it from two coin cells. It's absolute max supply voltage is 7v (not speced above 5.5v.)

[@PackratCND]

Dave: Welcome to the state of being "Human" !! I wish I could tell you the things that I have screwed-up/blown-up in my life ...lol.

[@JoshuasRecordings]

I once ran 20V into a 7V rail on a Sony amp. Then I heard a bang, and a cap vented and something else went bang. Opts!

[@computergarage-australia2301]

+Joshua's Recordings bet that made you jump

[@JoshuasRecordings]

+Computer Garage Yup, hit the switch on my power supply really quick!

[@siouxsettewerks]

It's certainly subconscious! You unknowingly wanted to justify the magic smoke emission from your logo in the outro, as otherwise, I don't remember seeing you fry a component in a vid!

[@transimpedance]

What does 10V reference mean?

[@MnemonicHack]

Your mistakes are our learning opportunities.

[@AzureFlash]

At least it was easy to fix!

[@TheVespap200e]

Oppps! It happens to the best of us. Its good you had a spare chip.😁

[@nrdesign1991]

at work I killed an RS232 isolating bridge, because some time ago I had to integrate a 24V power supply on the same wires! Doh!

[@PaulaBean]

I blew up an optocoupler yesterday - too much current through the LED - by accidentally turning a trim pot too low.

[@spinningquad8700]

Nice to see plenty of hot snot in the precision power supply

[@noahtheviking1]

I did a super special dumb move and soldered in a diode backwards on a guitar amp. And then to add to it I kept turning it on and off then got pissed because I knew what I did and pulled two traces because I wasnt paying attention to the heat on the iron.

[@kaoshavoc]

Thx for sharing this screw up lol. I am a new hobbyist and it is releving to see that even professionals can make oopsies. Luckily the biggest oopsie i have made that resulted in destruction was grabbing a 15v adapter instead of the 7v i meant to grab. Lets just say i had to build a new battery charger.

[@Kalkaekie]

Thanks for sharing !

[@sanfourbensanfer3911]

hi dave, it's the first time i saw u using a fluke 27 can u do a quick review please :)

[@44R0Ndin]

But how can it be broken if you didn't let the magic smoke out? On a more serious note, Why didn't you use steering diodes? Diodes are cheap, Op-amps and downtime are both expensive! The downtime cost might not have a monetary value, but I would be surprised if you didn't have better things to do than fix a test jig. In this case, Schottkey diodes are the obvious choice due to their low voltage drop and fast switching times. If you have some in 0402 or 0201 size (Imperial scale) you can probably use those and maybe some fine-gauge wire-wrap wire without even needing to re-roll the PCB. If it works "good enough" now it's better than working "better" later! Of course bodge wires and HF or high speed digital signals don't usually mix well, but a bodge wire or two isn't going to hurt this circuit that works at basically DC.

[@superdau]

Because once set up, this device would never see something much more than 1V (that's what the µCurrent puts out).

[@44R0Ndin]

superdau Would you plug in a computer without a surge protector? I wouldn't. Not even a laptop. This is the same idea. The diodes are basically a surge protector for the op-amp. They don't change the circuit's normal operation, but they do protect against the inputs going above or below the supply rails, which is exactly what killed the op-amp in this video.

[@superdau]

44R0Ndin Why would you need a surge protector? I never used one. You can't protect against every eventuality of user error. The next time he might have set it to 100V. protection diodes won't be of any help then, because even they can't take it. This thing is supposed to be used by people who know what they are doing. When testing µCurrents with it the only "power supplies" are coin cells in both of the devices, which can't deliver any current at all and they don't have the voltage either.

[@Regimantas_Baublys]

Nice video :) Dont forget input protection :)

[@jonathanwilhelm8891]

and tho shall keep WD-40 off top shelf and with in better reach. you never know when those pesky electrons will start squeaking.

[@Chriva]

Ohyes. Blew an ECU to smithereens last day by accidentally applying 12.5 volt to the 5V rail instead of vcc. It did not like it let me tell ya :p

[@Chriva]

*VPP. That's what I get for hurrying. :)

[@OzDelphi]

I hope you gave it a decent burial, Dave?

[@TheBdd4]

Thanks for showing the human side.

[@AstralS7orm]

This is why Zeners were invented. It's not like they're expensive...

[@phil.tsao.]

This just happened to me as well yesterday! Doh!

[@SteinErikDahle]

We've all been there.....

[@jonathanwilhelm8891]

precision doesn't have to come with beauty

[@monoham1]

wtf is an op amp? (besides a magic triangle that somehow violates the 1st law of thermodynamics)

[@Zamsky39]

Duracell batteries suck big time. Best price to capacity ratio - Ikea branded ones :D Highest capacity: Varta.

[@jamesknowles4839]

Personally, screw-up videos like this one are instructive and just as valuable as the instructional videos. Though technically this could be considered an instructional video. "Traps for young players" and how to deal with screw-ups.

[@stephenwoods4118]

Just remember Dave, poop always happens.

[@Cracktune]

I liked how informative this was (newbie tho)

[@scaleop4]

i know this is nothing to do with the vid..but 60fps and 50fps works well for your vids.

[@SurajGrewal]

that's nothing.... I've destroyed a graphics card by dropping a screw on to it while it was turned on.... literally screwed

[@SurajGrewal]

lucky it was just a 10$ second hand card

[@yoianrhodes]

scared me, then unscared me

[@SurajGrewal]

that's whats gonna happen when someone deals with a cheapskate like me :p

[@yoianrhodes]

If I fucked up that bad on my card I might just give up gaming... be like I can't be trusted...

[@AfdhalAtiffTan]

haha