Have to get this out...

ARG! I just really have to post this - the frustration is killing me. I have been sitting for 12 hours straight (besides taking leaks and getting cup noodles for food) programming and wiring a pcb, and finally, once I finish it - 2:30 in the morning here… It f*cking shorts somewhere and some led melts itself! (wtf?) I am sure you avae all had a similar experience (surely multiple actually), but wow this was a big blow… I’m afraid to touch the project now in the fear of repeated disappointment…

I hear you man. Why not have a nap or at least a shower and try again later. Is there a deadline you have to meet. Its like the simplest things one overlooks or doesnt notice are usually the ones that cause horrible shorts and smoke.

I was busy with a project a few months ago and made a dumb mistake. I was checking the PCB by powering it up without the IC’s in and making sure the power goes everywhere. For some stupid reason I decided to stick a wire in the VCC pin of the PIC socket and then proceed to short VCC to the LED pin sockets to see the LED’s come one. I touched the wrong socket and touched ground.

“Poof” a whole ground track vaporised >:(

Back in school, the way we had to write programs…
You’d have the actual program in one file, and you’d have a separate little short file that contained the commands needed to compiler the program (sort of like a .BAT file.) So after a 6-hour frenzy typing in this rather long porgram, I quickly entered the commands to create the command file, and OVERWROTE the six-hours worth of programming with the short file. Which wouldn’t have been half as bad if the last thing the editor had displayed hasn’t been the “are you you sure you want to overwrite this file?” question.
Sigh. Re-creating and re-typing the program the second time didn’t take quite as long.

What a bummer. Take a break and tackle it again. I’m sure next time around your PCB design will be better :slight_smile:

I am sure you avae all had a similar experience

Nope, 'fraid not: you’re the only one who’s ever made a mistake that dumb ;D

I don’t think I’ve ever managed to melt an LED. That’s a pretty good trick.

My personal favorite is the exploding electrolytic. The little ones that blow up because you soldered them in backwards have some amusement value, but the best one was about 2 cubic inches, which we were using to try to develop power for electronic controls for a propane-powered floor polisher with a magneto ignition. Unfortunately, our first guess at the required voltage rating was a te-e-e-ensy bit off. Fortunately, I was wearing a jacket: the scars would’ve been completely useless for picking up chicks. We were finding bits of capacitor in nooks and crannies of the lab for weeks after that…


My exploding capacitor (well I was only a trainee and it wasn’t my mistake) in 1967 was on a coil for a eddy current flaw detector for metal tubes.
The coil was taking 40A and the smoothing capacitor’s ripple current was exceeded. In those days before switching regulators ripple current was a relatively unregarded parameter.

It was a 3" diameter 6" high electrolytic that blew upwards, leaving the can intact. It was quite magical raining silver foil down for ages. You get similar effects nowadays for parties but without the capacitor.

I used to get those effects at parties, but when I got a career I started worrying about being arrested and gave that sort of thing up :sunglasses:

Homemade electronic door bell, powered by 120V–>16V step-down transformer, confused the primary for the secondary, thus stepping 120V up instead of down.


You’d have the actual program in one file, and you’d have a separate little short file that contained the commands needed to compiler the program (sort of like a .BAT file.)

Oh yes, the joys of makefiles. I made it through 4 years with a makefile I copied from someone in first year, just making minimal changes for each assignment.

It does remind me of the time after a 36 hour coding session, 2 hours before an assignment was due, I was cleaning up the directory to get it ready for submission. When I typed “rm *.bak” to erase my backup files, I managed to hit enter before the period so I executed “rm *” and had “.bak” on the next line.

To relate to the OP, I usually use 1-pin pieces of male header connectors to make test points on my prototyping board and I have a bad habbit of not labelling them. On one board I hadn’t touched for 6 months, I went to power it and applied power to the +5V pin after my regulator rather than the Vin pin before my regulator. I put 9 volts on everything that was supposed to get 5 volts. Luckily the only casualty was the ATmega which was socketed. So what could have been a 15 hour mistake was just a $4 mistake :slight_smile:

I don’t think I’ve ever personally blown up an LED, but a few projects ago I set an employee to building a bunch of LED pairs on long wire tails that were to be installed in some scenery, and then went and worked on something else. I came back later to a nasty smell and a bewildered employee who, come to find out, had put mains plugs on the other ends of all of the tails (they normally only deal with mains equipment), and then plugged one of the pairs into the wall to “test” it. At that point I indicated the batch of 6V wallwarts that had been purchased for the job, and the employee had an “aha!” moment.

My most common problem when I get tired seems to be forgetting to change the mode on my DMM when changing measurements. Fortunately, my bench supply has gracefully withstood my inadvertently measuring its short-circuit current more than once. . .

not related to electronics per se, but almost worth an IT darwin award:

little me was experimenting with partition tables/bootloaders a bit on somebody else’s laptop (with really important data, what else) and we ended up deleting the MBR of his disk and rebooted the computer. next thing was something like “No operating system found…”, even worse: no partitions found! oops, but no problem because I made a backup of it.

Now ya’ll can guess where the backup of the bootsector was saved.

Just in case this happens to YOU, you’ll want to use THIS to save your ass (last word was probably censored again).

HOORAY! ;D ;D ;D ; woke up 20 minutes ago and fixed the issue first thing (damn biological need for sleep)… seems I wired the wrong pin to a +5v rail. It’s fixed now, but I did run into another issue that I want to throw out real quick for ya -

I’m running two servos, the PING, an h bridge’s 5v ic power (not the motor power) and 2 enable pins (from the h bridge) all from the arduino’s 5v pin. It worked fine for a few seconds but then the arduino began to restart itself every 3 seconds or so and try to run the code (it would start running, then stop, and start again)…

Am I running out of current due to the many components hooked up? or Is this some sort of short? (I wiggled the wires around, but the restarts continued at the same rate, never corresponding with a wiggle or pull on a wire).

Unless you’ve got a wiring problem, the servos are probably the only things putting a significant load on the supply, can you disconnect them and then run the sketch to see if it still resets? It could also be a software problem (overrunning the end of an array or somesuch, for instance).

Thanks, just tried that - seems to have less issues, but some sort of delay randomly occurs still… perhaps thats just a code issue…

any way of adding some more current to the 5v without blowing the arduino?

any way of adding some more current to the 5v without blowing the arduino?

Yes, use an independent external 5vdc power supply that has maximum current rating well above your estimated needs. The Arduino’s internal 5vdc current capacity is rather limited and really only pratical for low current external devices like small LEDs, most ICs, etc. When you start interfacing to motors and servos you really need to use additional external power.

If and when you do utilize external DC power supplies for your external loads be sure to remember to wire the ground from the external supply to a Arduino ground pin.


What are you using to power the arduino, usb or external? You might want to power the servos with a darlington transistor array which will amplify the current. When there is no load on the servos they won’t draw much current but when they are loaded they could exceed the current limit from the arduino.