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Dos And Don'ts To Prevent Release Of The Magic Smoke


The extent of my knowledge in electronics is that they run on magic smoke and if you let it out they stop working.:)

I found a thread on hooking up H-bridges prevented me from frying my EZb 4. I would like a one stop thread where we could post our experiences where we have fried our boards and other components.

I've gone through all the tutorials and have found additional info on the topic there as well. Though it would be nice to have a one stop shop for the combined wisdom of others on this topic.

Thanks much,



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I lost $70 in two seconds when I inadvertently reversed polarity on one of my sabertooth 2 x 5 motor controller boards... Lots of blue smoke that day...:)
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Not that I want to toot my own horn but I've never released any magic blue smoke... my secret is simple, read everything, understand it, then connect it up to the magic of electricity:)
LOL... @Rich... Knock on wood dude!... Have you checked Melvin? He could be going up in flames as we speak... :P
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He's fine, his battery is removed (I don't trust him not to turn himself on and run riot in the spare room!):)
They say a Carpenter measures twice and cuts once.
Why not use the same rule in electronics

all the circuits and connections are available to you on the ARC manual,ask questions on the forum if you don't understand before you make that final power connection if you are unsure.Make it as detailed as possible even include a photo.

Smoke of various colours usually is a result of circuit overload or incorrect polarity.

Always use a fuse on any power circuit ,or if you connect first with a bench power supply and limit the current you may identify any possible short.

This will ensure you have a smokeless experience.
I smoked two TTL-WiFi boards of two brands trying to convert my EZ-b v3 from Bluetooth to WiFi.

Both were examples of trying to work on something when I was too tired and making silly mistakes.

1st was (I believe) mixing the ground and power.

2nd was giving 5 volts to a 3.4 volt board.

Lesson in these is to not work with delicate or expensive electronics when not in possession of all of your faculties.

This is sort of a repeat of Alan's (and others) sage advice:
Check everything.
Resolve any ambiguities the diagrams or instruction leave you with.
If you are not absolutely sure how the power is to be hooked up, ask for help.
Make sure you know what voltage each circuit needs.
Check everything.
If there is still some doubt - go do something else. Come back to the project with a fresh mind.
Check everything.
If you can, divide the project into smaller or simpler component parts Maybe, start out with only 1 servo connected.
Check everything.
A quick disconnect if something is wrong probably won't help. The blue smoke is much faster than you are.
Check everything.
When you are confident that the polarities are right and the voltage levels are correct, connect it up and enjoy!
Also, DON'T plug anything into the system with the power ON.
Ya, whatever. I say if you haven't blown something up then your not doing much bot building. *blush*:D

I burned out a V3 EZB by draging an energized 5vdv power source over the digital ports. Didn't even spark so I didn't even have the consolation of seeing a blow. However then I turned a live pot past it's one turn limit and at least it had the dignity to shoot flames up into the air for about 3 inches. That was exciting. *eek*
Once a Student came in my Electronics repair shop (1970). I was working on a tube type guitar amplifier when he broke my concentration by saying "What is a rectifier?" Well, I answered rather quitely "One is right Hereeeeee! I pointed to one in the circuit and it shocked the crap out of me. (it was in a bridge circuit that had 117 VAC hooked to it. After I stopped convulsing , he said "OK, thanks."and walked out.

That was one of my most embarrassing moments of my life.
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Oh I've had electric shocks but I was an electrician for a few years. I've lost count of the times I've touched live 240v cables. Is it wrong that I actually quite like the sensation?

And Dave, you are right, I haven't been doing much bot building but hopefully that'll all change in the new year:)
I have been lucky and have only reversed the voltages on my ez-b v3 and blew a fuse.
Speaking of shocks, I had a wall that built up A LOT of static electricity(near an air filter machine that made static electricity to filter out particles) and when I went to switch the light switch on I got a huge shock that made me jump across the room! I've also stuck wires in outlets as a kid...:D *blush*
OK, if we are going to talk shocks...

Once I was talking on the phone during a thunderstorm (land line, copper, one of those hold really heavy Bell 500 sets.... this was 30+ years ago, when I was in high school) and lightning hit a tree right outside my house. A shock went from the mouthpiece of the phone into my chin. As if that didn't hurt enough, my whole body spasm-ed, and my right arm drove the phone handset into my jaw. Didn't break it, but I had a huge bruise and couldn't comfortably eat or talk for a week. The answering machine on that line was fried, as was the one on my mother's phone line, and apparently my van was also hit because the stereo was dead when I went out the next morning.

I also lost a car stereo a couple of years ago when my car was hit by lightning while I was driving it, but other than the stereo, the car acted as a Faraday cage and protected me from getting shocked.

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Alan, you don't have much luck with lightning! Good thing you weren't doing 88mph!;)
@Rich... as smart as Alan is, I doubt he had a flux capacitor.... Queue Huey Lewis....:P

I also used to have a cat that liked getting static shocks. After being pet, she would go to the nearest metal surface (well,she was't that smart, she would try on bookshelves and chairs too) and touch her nose to it, then bite the air when she got shocked, but would then keep repeating it to try and get another shock.

I fried a number of cmos chips by handling them as I would TTLs. Only later learning they were much more sensitive to static shock. I fried two very expensive static ram chips (circo mid 80s) that way. Since then I've always touched the ground before touching components.