Author Topic: What`s your expensive mistakes?  (Read 4241 times)

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Offline Fredrik AnderssonTopic starter

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What`s your expensive mistakes?
« on: September 28, 2007, 07:40:24 AM »
Yeah, we have all done mistakes while working on robots, right? Fried stuff and such. It would be interesting to know what accidents everyone have got into and what it have cost.

Even though i am a beginner i have already fried four servos and a CMUcam (which makes me wonder if it`s maybe cause i am a beginner) for a total cost of about 250 dollars. That hurts :(

Now you list your accidents!
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Offline hgordon

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Re: What`s your expensive mistakes?
« Reply #1 on: September 28, 2007, 08:04:01 AM »
I'm not a beginner, but I regularly make mistakes like reversing the power connections when testing prototypes, reversing transistors on designs, and sometimes installing the wrong headers or connectors.  Probably the most expensive set of mistakes was with a prototype processor board that cost about $1000 to design and build just for 2 boards.  The processor module had "border pads" for soldering, and I took a shortcut of using a hotplate to flow the solder for mounting instead of hand-soldering the 80 pads.  The result was that one processor never worked, and the other had bad flash memory.   I could have ordered more processor modules, but at $250 each, I decided to instead wait for the next prototype revision, and the wait was the most expensive part of the error.
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Offline JonHylands

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Re: What`s your expensive mistakes?
« Reply #2 on: September 28, 2007, 08:16:59 AM »
I fried a $400 PDA by sending +5 volts up the ground like. I had a 3-pin plug on the end of the serial cable coming off the PDA, and a 4-pin header on the board (4 pins because when I plug in my DS-275 to control the board from a PC, I provide power to the DS-275 transceiver from the main board).

So the header was +5, ground, Rx, Tx. The PDA only used Ground, Rx, and Tx. I accidentally shifted where I plugged it in, and fried the PDA completely.

Now when I build a serial cable for that board, I use a four pin plug, even if I don't need the +5...

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Offline Admin

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Re: What`s your expensive mistakes?
« Reply #3 on: September 28, 2007, 08:54:01 AM »
Ive spent $150 on DC motors, not realizing they were 24V.

Spent $300 on servos, not realizing they had 1/10th the torque I needed. This is why I always stress to calculate before buying motors!

If you count pain as expensive, Ive burned myself on my first attempt at an H-Bridge. The MOSFET permanently had my fingerprint etched into the aluminum after that . . . took a week for the pain to go away . . . Then the time I almost lopped my thumb off with a bandsaw, lots of blood . . . always be afraid of your tools! I wear safety goggles for almost everything, had soooo many near accidents that could have resulted in eye loss . . .

And of course, Ive wasted huge amounts of time (hundreds of hours) redoing parts/circuits - time is money!

The biggest mistake I always make is hole tolerances when drilling. I rarely get them right . . . its not expensive, but wastes huge amounts of time.

Offline Gertlex

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Re: What`s your expensive mistakes?
« Reply #4 on: September 28, 2007, 06:29:23 PM »
Most expensive, though it didn't cost me anything, was a carbon fiber fairing that I trimmed slightly wrong, and I *think* meant the whole thing had to be junked.  To be fair, I had asked a couple others about which lines from the mold to follow, but none of them actually knew the exact details themselves.  (One person knew the details, and she wasn't around)

I wear safety goggles for almost everything, had soooo many near accidents that could have resulted in eye loss . . .

Same here.  I've been crazy lucky.  Once my brother shot a rubber band at me and hit me between the eyes.  I've been hit on the side the nose by a pneumatic cylinder (I don't remember exactly how...).  I've had a heft coil spring thrown at me (in retaliation for flicking a tiny particle at my friend) that hit my safety glasses.
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Offline Ro-Bot-X

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Re: What`s your expensive mistakes?
« Reply #5 on: September 29, 2007, 10:56:47 AM »
I have fried 6 I/O pins on my OOPic-R board by reversing the servo plugs. Besides that, I have a ATmega8 with a wrong fuse setting, not even remember what I did wrong to try to revive it. A couple of servos with gears stripped... One by me, and one by my daughter shaking (realy hard) my robot's hand! She is one year old and doesn't know it's hurting Eric... and Dad.
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Offline annoyin_kid

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Re: What`s your expensive mistakes?
« Reply #6 on: October 02, 2007, 02:53:11 PM »
around a month ago i fried the left channel on my dad's mp3 player while testing my project in school (accidentally had 16.6V go in the wrong way).
it turns out that the switch that i was using was faulty and was shorting interanlly letting the 16.6V in.

a few days before i fried the mp3 player i also almost fried my whole project that i'd been working on the whole year. i was testing one day and then suddenly sparks came out of the bottom of one of my circuit board. luckily it survived.

before this i fried 2 speakers in less than 20 mins (no one in class had fried anything more than a resistor and a cap before this) after trying to find what was wrong i found that i was putting in around 10W into a 0.25W speaker. this was the day i learned what the power ratings were for.

i'm sure there are going to be bigger things that i fry in the years to come but for now these are all that i've fried.

Offline SomeSaba

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Re: What`s your expensive mistakes?
« Reply #7 on: October 02, 2007, 07:01:00 PM »
i miscalculated the torque i needed and bought a $100 servo when i needed a $130 servo   :-\

Offline voyager2

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Re: What`s your expensive mistakes?
« Reply #8 on: June 12, 2010, 06:36:11 AM »
I fried my $50 robot's ATmega168 when I applied voltage the wrong way, also fried my regulator and a capacitor or two has gone "POP"(only 0.1uF though, whew!)
Hot microchips tonight, anyone?
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Offline amando96

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Re: What`s your expensive mistakes?
« Reply #9 on: June 12, 2010, 11:05:54 AM »
I never have  :D
When i was a beginner i used to be really scared of killing parts, because they weren't easy to find, so i double, and triple checked everything before applying power.

I have though bought things by mistake, but so far eventually i used them all, and not that expensive, only 30 for both.
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Offline little-c

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Re: What`s your expensive mistakes?
« Reply #10 on: June 12, 2010, 02:48:36 PM »
cooked two micros, fairly expensive at $160 for both. I had made a header board so I could remove them from the project out of strip board, and subsequently cooked both, cause I hadn't cut the traces running from one side of the board to the other. I never twiged until I scraped the version it was for. you have no idea how much testing didin't find that fault.




Offline Cristi_Neagu

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Re: What`s your expensive mistakes?
« Reply #11 on: June 13, 2010, 01:19:33 AM »
The most expensive thing i fried as of yet is a 555 timer. That was through ware and tare, because i bypassed a resistor that i think wasn't supposed to be bypassed. But it did work for a while...

Offline random robots

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Re: What`s your expensive mistakes?
« Reply #12 on: June 14, 2010, 03:36:41 PM »
killed couple of 555s, fried some leds and transisors, nothin' over $2 really.
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Offline TrickyNekro

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Re: What`s your expensive mistakes?
« Reply #13 on: June 14, 2010, 03:56:47 PM »
Failed at chipping a PS2 slim... God that was painful...
Of course had nothing else to do that trying to unsolder the whole chip to get some pins right...

And just forget to mention that it was something like a 256pin TQFP IC...
Got it working but... it was a heavy mistake for not having a good respectable soldering gun at the time...
Skill is not enough... The right tools come always in handy...

I don't remember anything significant by the time...
Some transistors and some LEDs fried... that's common...

I got some AVR fuse locked... but keep them... and got them unlocked with an STK kit... :-D


I also remember killing some power supplies... But... they were beyond repair before I started the repairing...
At least repairing them to a compared price to buying a new...



That's all from me... ;-)
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Offline Webbot

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Re: What`s your expensive mistakes?
« Reply #14 on: June 14, 2010, 08:07:57 PM »
Fried myself once as a kid when was starting electronics.

Decided to test out my 240V AC powered circuit with everything laid out on my bed.  Leaned over to test something with my multi-meter just enough for the 240V side of the transformer to roll over onto my hand !!

Wont do that again in a hurry ! Hair like this:  ???

Lots of mis-purchases and trousers splattered with etching solution.

At least software doesn't try to kill me !
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Offline SmAsH

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Re: What`s your expensive mistakes?
« Reply #15 on: June 15, 2010, 12:33:39 AM »
At least software doesn't try to kill me !
We'll see...

The worst i've had is a bad ass shock from a coil gun capacitor...
As for the most expensive stuff up, try frying a $150 processor >:(
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Re: What`s your expensive mistakes?
« Reply #16 on: June 16, 2010, 07:39:03 AM »
Quote
At least software doesn't try to kill me !
If you put a Microsoft OS on your robot, the 'blue screen of death' will have a whole new meaning . . .

Offline Asellith

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Re: What`s your expensive mistakes?
« Reply #17 on: June 16, 2010, 08:11:50 AM »
If we include work projects I got a good LONG list... Lets see

A $6000 FM transmitter Tube (yes some of us still use vacuum tubes. They are just bigger then your head)
A $30000 Campanile Control System (In my defense I rolled my own system for under $500 and some scrap. Also it was 25 years old when I broke it)
A $150 cellular modem

I have lots of others I just can't remember any more mistakes right now :)
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Offline TrickyNekro

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Re: What`s your expensive mistakes?
« Reply #18 on: June 16, 2010, 02:28:02 PM »
Quote
At least software doesn't try to kill me !
If you put a Microsoft OS on your robot, the 'blue screen of death' will have a whole new meaning . . .

Pffff....
Same with motor controller drivers not arriving at the same time, with the new Kernel if you ask me...
For whom the interrupts toll...


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Offline Derme302

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Re: What`s your expensive mistakes?
« Reply #19 on: June 18, 2010, 02:27:59 AM »
So far I have only made mistakes that cost under $5...brought the wrong capacitors, got 10v when I need 16v and I have also fried a couple LEDs by putting to much voltage in them. I just hope my luck holds. ;)

Offline voyager2

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Re: What`s your expensive mistakes?
« Reply #20 on: June 19, 2010, 04:43:23 AM »
Just thinking, I've fried a few (4) LEDs too, one was a dodgy solder job, another was SMD, used to much solder and covered the whole thing! ::)
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Offline Gertlex

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Re: What`s your expensive mistakes?
« Reply #21 on: June 28, 2010, 09:30:21 PM »
Electrical division needed me to drill something out.  Drill bit got pulled in a bit too far, and got the barest edge of the PCB.  The MPPT was deemed an unknown for reliability because of this, and therefore not usable.  $2000 item. Ahh yea.
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Offline codeblue

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Re: What`s your expensive mistakes?
« Reply #22 on: June 30, 2010, 11:35:55 PM »
My high school club lost our entire quadcopter last year(like $1000 and 300 hours of work). So we had everything working really well as far as landing on our pad on land. So we decided to try it on water, but we simply had a 5 X 5 foot pad for it to land on and the pad floated on water. We tested it in a wide open pond on a day that had like 10 mph winds. The quadcopter was programmed to calculate its landing before going to the pad, and to not make sure it was still under it in the last few seconds of flight.. It undershot the platform by like 6 inches and it fried the cmu cam, main board, accelorometers everything  :'(

Offline dunk

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Re: What`s your expensive mistakes?
« Reply #23 on: July 01, 2010, 04:45:56 AM »
At least software doesn't try to kill me !
heh, a good few years ago now i caused one of my work sites to receive a phone bill in 3 stationary boxes.
i mis-configured an ISDN modem to test call a server every 1 second instead of every 1 hour...
it was only a few £thousand. we did a deal with British Telecom and got it to a reasonable figure.
admittedly is wasn't software killing me but had i been there when the bill arrived the site manager would have had a go...



since then i've been involved in network outages that have affected sizable portions of the internet and cost millions.
only one of those was my fault though and i had that one fixed within 30 minutes. it probably cost under 200k if you take loss of earnings and wasted man hours into account.



probably the most stressful moment that was entirely my responsibility and *nearly* turned expensive
was breaking 480Gbps of trans-Europe and trans-Atlantic connectivity at about midnight GMT.
it was a compound problem involving multiple pieces of defective hardware and a previously undocumented software bug on the DWDM system.
one of my contractors on a motorbike managed to defy the laws of physics (not to mention the road laws of the country we were in) to get to the nearest depot for parts.
had i not got this system back up before morning it would have had a considerable affect on how western Europe and eastern US uses the Internet for the duration of the issue...

after much shuffling of hardware and stealing from backup systems we had everything back online for morning.
we actually managed to take advantage of the complete network outage (something that we would never have got permission to do) do move circuits i had been waiting for years to get down time on.



that's all just work stuff though.
it's expected and that's why i was there: to fix things when they go wrong.

the mistake that is currently stinging is the firmware on UAV test platform locked up yesterday.
the whole project just flew away. i last saw it circling happily upwards a few miles away.
i could have avoided this by properly testing the latest firmware revision on the bench instead of being impatient to play with it.

the cost of the parts is probably under 100Euro but the time involved in sourcing the parts and rebuilding is quite large.

sucks.



dunk.
« Last Edit: July 01, 2010, 06:50:01 AM by dunk »

Offline Asellith

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Re: What`s your expensive mistakes?
« Reply #24 on: July 01, 2010, 06:35:48 AM »
Dunk you make me feel better about my problems. I'm the last and only line of defense at my radio station. I now have 2 full power stations I take care of and at this point they are both run on my own designs and I hate documenting things. So when things blow up they call me. When an AC unit fails and a station shuts down because its 130 F in the room everyone looks at me and says fix it. So I make 5 calls and wait while everyone glares at me and wants the station back up. The AC company takes at least 2 days to do ANYTHING and my techs take at least an hour to get to the site and about 5 hours to call me back. Managing sites remotely without dedicated personnel is the worst. and at $85 an hour the engineer 5 states away is making WAY more cash then I am... I need to get on that side of the bill someday.
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CorSec Engineering
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