What's your most expensive electronics mistake?

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We all know it's jolly difficult to get the magic smoke back in your chips once you've released it... Inspired by the following two posts, I want to know what's your most expensive / embarrassing electronics error, and whether you can top my most recent mistake (which I shall reveal a little later - oh the suspense... :oops: )

https://www.avrfreaks.net/index.p...

https://www.avrfreaks.net/index.p...

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As a youth... Production test of military helicopter circuit card batches. Power supply set wrong; toasted most all in 1 second. Don't know, but probably $20K.

And hard to measure in $, but (I didn't do it but was in charge), at the TV station in big city, someone bored with the baseball remote we were transmitting, accidentally patched out to air the NFL game. For a while.

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Wired a bank of sixty 12V batteries to a prototype switching power supply through a relay controlled by a switch. Threw the switch. :shock: I had never seen so many FETs spew so much molten metal in all my life. The room was filled with sunlight for about 30 seconds. Polarity was reversed. :roll: Cost classified.

"I may make you feel but I can't make you think" - Jethro Tull - Thick As A Brick

"void transmigratus(void) {transmigratus();} // recursio infinitus" - larryvc

"It's much more practical to rely on the processing powers of the real debugger, i.e. the one between the keyboard and chair." - JW wek3

"When you arise in the morning think of what a privilege it is to be alive: to breathe, to think, to enjoy, to love." -  Marcus Aurelius

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Getting into this business in the first place has been my most expensive and embarrassing error. Seriously thinking of walking away from it for good too.

As far as $$ boo-boo's go, I was asked to troubleshoot a design at the fiber optics company I worked at. It had a real expensive laser coupled to a prototype WDM and custom photodiode receiver. Dummy me I did not notice that the regulators were jumped out when I applied 12vdc to it and poof! The laser smoked up massively and in my startled state smacked the unit off the table and shattered the WDM. Toasted the photodiode too.

Laser $8000
WDM $6000
Photodiode $1200

I still had a job and enjoyed the ten years I spent there anyway. ;)

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign, did you (a part of whole cost, of course) pay for the smoked equipment?

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NOPE! Although I did not adhere to rule #1 which is to look everything over BEFORE applying power, The owner pinned the blame on the VP of engineering as there was no sound reason to jump the regulators. He ended up not paying for it either due to some fancy talking by him, and the project was apparently a "Can it be done" thing.

The vendors were none too happy about it though as they heavily discounted the devices in expectations of a big sale. Oh well a LONG time ago.

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Believe it or not... I cannot remember any mistakes, expensive or otherwise. Isn't the human brain wonderful? (Ego-centric bias)

Ross McKenzie ValuSoft Melbourne Australia

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valusoft wrote:
Believe it or not... I cannot remember any mistakes, expensive or otherwise. Isn't the human brain wonderful? (Ego-centric bias)

It (the brain) protects himself)

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Starting electronics 50 years ago this year. :(

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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As best as I can remember I was 12 when I made a crystal set... 53 years ago... oh and it didn't work first go... but did after I improved my soldering. Maybe that was my one mistake!

Ross McKenzie ValuSoft Melbourne Australia

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I deal with electronics for about [ 28 (my age now) - 9 (when I was started) = 19 ] years this year. But some days ago I realized I know nothing about it(((

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I had been at Micro for a couple weeks when Mike asked me to put together a board for him. The prototyping board had pins 1 and 2 connected together, and the first thing I had to do was separate them 'cause in the newer systems, pin 1 was -12v and pin 2 was data bus 0.

Imagine the sound and smoke when the tiny thread of copper I'd missed put -12v to data bus 0 of that large TTL computer!

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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I still maintain it wasn't my responsibility but it involved the mains electricity feed to this transformer...

Attachment(s): 

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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That's not a trannie! Its 3 home brewing kegs on wheels.

Ross McKenzie ValuSoft Melbourne Australia

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My gosh! It looks just like the Flux Capacitor's available from Digi-Key!

JC

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valusoft wrote:
That's not a trannie! Its 3 home brewing kegs on wheels.

Drinking that beer is the same as having a 6 kV shock :D

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All that to power Torby's model railroad?

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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I once turned this off by mistake:

Starting with a dodgy audio drive amplifier, I jacked it out with what turned out to be an incorrectly wired jump lead - which resulted in the right channel being inverted and sent to the left channel.

The transmitter summed these, got zero, and thirty seconds later decided that as there was silence, it could go to sleep.

So it did.

Three minutes later, the next transmitter in the chain, which was monitoring this one, decided the same thing, at which point people started to complain...

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... proved that they were actually listening. No one likes to be ignored... and you weren't.

Ross McKenzie ValuSoft Melbourne Australia

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barnacle wrote:

I once turned this off by mistake...

Ah, so you might recognise my transformer, or were the C4 transmitters at Emley the Marconi ones?

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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Quote:
As best as I can remember I was 12 when I made a crystal set... 53 years ago... oh and it didn't work first go... but did after I improved my soldering. Maybe that was my one mistake!

That is so spookey.... I did exactly the same thing at about the same time and same age as you...

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Quote:
I never make mistakes...

I thought I made one once,

but I was wrong.

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I made a crystal radio. I was 11, and it wasn't as long ago.

I also had one in a little bakelite case that somebody must have made generations before.

For the 6th grade demo, where all the little kids got to come and see our projects, I substituted a diode for the crystal so it would work without having to find a good spot with the cat's whisker.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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My first crystal radio was in the 50's. Then I upgraded to a galena crystal with cats whisker. (Hmm... perhaps downgraded...) Then I used a rusty razor blade for the detector, due to reading either a Rick Brandt or tom swift junior book. (I can not recall which.) The rusty razor blade worked just fine, thank you very much!

Ah the good old days. Sigh.

I am building my qrp kits that I have collected over the years now. Relearning my morse code. Lots of fun!

dit dit

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stevech wrote:

And hard to measure in $, but (I didn't do it but was in charge), at the TV station in big city, someone bored with the baseball remote we were transmitting, accidentally patched out to air the NFL game. For a while.

He He. That's fantastic. I've heard a similar storey of someone accidently broadcasting porn to the screen in the Superbowl in Tucson, Arizona.

larryvc wrote:
Wired a bank of sixty 12V batteries to a prototype switching power supply through a relay controlled by a switch. Threw the switch. :shock: I had never seen so many FETs spew so much molten metal in all my life. The room was filled with sunlight for about 30 seconds. Polarity was reversed. :roll: Cost classified.

Holy cow Batman! That must have been scary. I've seen videos of 480v bus bar short circuit. With 720v of batteries that must have been one hell of a fireworks show.

I once shorted out my 24v 150Ah battery bank on my UPS. Within a fraction of a second the terminal connector that made contact vaporised leaving almost no evidence of it's former existence other than a few scorch marks where molten metal shot across the top of the plastic battery case melting it along the way. I couldn't find any metal around the room...

But that didn't cost me much, and no one knows it happened, so I got away with it... ;-)

My most expensive and embarrassing involved one of these chips. I designed a board with two FPGAs on it. Boards could be expanded with peripheral modules to add things like DDR memory, HDMI SPDIF etc. Power to the peripheral modules was supplied by the FPGA board at 12v and regulated down as necessary. An alternative use for the expansion connectors was to stack FPGA boards together to expand the logic space.

When the board arrived from the manfacturer I was on holiday so the bring up fell to a colleague. I arrived at work a few days later, fresh from my holiday only to find myself presented with the rubber chicken. Unfortunately for me I had inadvertantly designed in a kill switch by failing to spot the potential for reverse current flow when a certain combination of components were turned on by software. Queue 12v applied to the 1v8 rail of my expensive FPGA. $25k down the pan.

Software and verilog solutions to prevent the problem in future were quickly made and distributed to end users. A hardware modification was also designed and a program of rework started. So you can imagine my dismay when a I got word that a second board had been destroyed from the exact same fault because the user hadn't applied any of the three patches, any of which would have prevented the loss.

Took me quite a while to get rid of that $50k rubber chicken!

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Wasn't a mistake, but an unexpected result:

One of my first electronic projects was an amplifier from a kit from radio shack. Remember the red plastic box with holes in it like perf-board?

Saturday afternoon, Dad was laying on the couch "watching" baseball, and I was sitting on the floor putting the kit together. I carefully followed the diagram. Naturally, when I first connected the battery, there was no sign of life, so I was going through the schematic, putting my finger on each connection and checking where it went.

I touched one connection, and it sang "The Star Spangled Banner." I didn't think it appropriate to take my finger away until it was finished. When I did, Dad said, "That was impressive."

It only took a few minutes more to find my mistake.

Then Dad turned on the radio and indeed, the local AM station had just started a ball game. I guess I coupled the AM signal to the base of the transistor, which amplified it to the speaker.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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In 1993 there was a massive storm in the North Sea off the east coast of the UK. I was in Cromer, Norfolk at the time at a friend house near the pier. A barge for the oil rigs came adrift at sea and crashed through Cromer Pier.

Queue fireworks as the gas pipes and electricity cables feeding the buildings on the pier were severed. Queue lots and lots of police and fire engines.

What made me think of it was the fact that my friend and I could hear everything that was going on via the police / fire radios. Somehow my friend's audio amplifier (Pioneer A400) was receiving the police radio and playing it out via the speakers.

There was nothing we could do about it other than turn it off. Input selector and volume control made no difference to the speach we could hear.

The amp was a plain old 2 channel analogue amp. No radio receiver. Just a CD player and speakers.

I expect we were receiving the IF frequencies and something in the amp was able to demodulate an AM signal.

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Rarely, drowsing in bed in the morning, I can ever so faintly hear the local (strongest by an order of magnitude) 91.5 MHz FM station. Have no idea what is doing the demodulation, I would say dental work but it goes away when I block my ears.

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Are you wearing your tin foil hat at the same time? :lol:

Ross McKenzie ValuSoft Melbourne Australia

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FM demodulation is way more complicated that that!

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My wife 'hears' the audio from the satellite Rx. TV is off and sat. Rx is on standby.Change cannel, she hears the change and tells me what is being said :(

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FM demodulates very easily if you're tuned 'on the slope' rather than at the actual frequency. I can see it demodulating with a diode in a tooth.

Not so sure about the satellite receiver though - unless it's an analogue signal and she's hearing the IF strip.

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Reference the dental radio

I think I experience the same phenomena. It's hard to prove.

When I'm trying to go to sleep at night I sometimes hear a radio/tv/whatever playing. It is very faint, and I can tell there is talking going on, sometimes music, but mostly voice.

A couple times over the years I've crawled out of bed to go search the house for a radio or TV that was left on, never to find one.

I never hear it when I am active during the day, only when I am resting quietly late at night.

With my abundant dental work, (sigh), I probably ought to be able to tune in several stations!

I though Lucille Ball stated that she could hear radio through her dental work. A quick search through her Wiki failed to show it, however.

I recall one of my first crystal radios used one of my father's razor blades and a pencil lead attached to a paper clip or safety pin as the diode.

JC

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Maybe that is why some folks take their teeth out at night :lol:

Ross McKenzie ValuSoft Melbourne Australia

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I was 14 and built a darkroom in the bathroom under the stairs. It was a little warm and stuffy from the enlarger lamp, so I appropriated Mum's old hairdrier and pulled it apart. I wanted the fan as an exhaust fan, but didn't need the heating element, so simply cut it away and jumped the wires right to the fan motor.

It's spread out on my desk, and I plug it in to test. Didn't realize that the heating coil dropped the 240V and current to manageable levels for the motor - an open-frame motor. The fine wire in the motor vaporized, and a puff of copper vapor blew up at me.

My hand was blocking, so it didn't coat my face and eyes. But all the skin on my palm blistered from the burn, and a chunk of something sliced my little finger. Still have the scar from that ... The burn cream and bandage weren't too expensive, but the almost-face-and-eyes, yah, that might have been expensive.

Dean 94TT
"Life is just one damn thing after another" Elbert Hubbard (1856 - 1915)

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I'm with a few of the other posters. Not becoming a lawyer or a banker, that's the expensive mistake.

Four legs good, two legs bad, three legs stable.

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This topic is amazing... It's nice to see that we aren't alone... :)

I'm trying to remember my worst mistake:
- Pop an oscilloscope on my second year;
- A bad PTC choice in a board so we need to go to the products that was in the installed. This PTC blocks the power to the others boards and the product stops. :(

Regards,

Bruno Muswieck

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Regarding hearing things......
Both the wife and I hear either a radio station or the cable box at night as well. Not loud but it's there. If I get out if bed it goes away. Nothing on in the house either

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign wrote:
Regarding hearing things......
Both the wife and I hear either a radio station or the cable box at night as well. Not loud but it's there. If I get out if bed it goes away. Nothing on in the house either
Saves on electricity so why complain?

Ross McKenzie ValuSoft Melbourne Australia

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valusoft wrote:

Both the wife and I hear either a radio station or the cable box at night as well. Not loud but it's there. If I get out if bed it goes away. Nothing on in the house either

Maybe a strong nearby AM radio station and a rusty bed frame or spring acting as a rectifier? Not uncommon for such. Also, a strong AM station can get into the speaker wires, or an amplified speaker whose amp is always-on.

People I heard of, near 50KW AM station KFI in Los Angeles, had many problems - including needing a filter on the phone lines as KFI would be heard on the phone.