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Small explosion, did I do something wrong or was it defective?

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Triode

Active Member
So, I just connected a 12V 1 A voltage regulator to a 15V 1 A DC power supply and it exploded like a small firecracker. It was connected to the circuit properly. Is a 15V supply really that far too much or is that a defect? The datasheet says it can take up to 35V input.

Thats the first time I've actually had a part explode.
 

Leftyretro

New Member
So, I just connected a 12V 1 A voltage regulator to a 15V 1 A DC power supply and it exploded like a small firecracker. It was connected to the circuit properly. Is a 15V supply really that far too much or is that a defect? The datasheet says it can take up to 35V input.

Thats the first time I've actually had a part explode.
"Is a 15V supply really that far too much or is that a defect? The datasheet says it can take up to 35V input."

No 15vdc is not too much and that is not the reason it blew up, something else caused it.


"It was connected to the circuit properly. " Was it connected properly for sure? Maybe a wiring drawing show how you built it would help.

"Thats the first time I've actually had a part explode."
Well it comes with experiance, less explosions over time as you gain knowlege and experiance.;) Most likely won't be the last time either, to error is human.

Lefty
 

picasm

Member
because it was working with a 12V 300mA supply, but that was a bit weak for the amplifier
In that case, your new power supply could be faulty.
Check the actual output voltage and also it could possibly have a faulty rectifier allowing it to output AC which would blow your regulator.
 

MrAl

Well-Known Member
Most Helpful Member
Hi,


I have seen regulators hooked up wrong and not blow up. They blow
out (so they no longer function correctly) but they dont blow up.
This leads me to believe that something very unusual was also in
play here.
Perhaps check your input voltage to make sure it was the proper
type (DC) and that it was really the proper level that you think it
was.
When you order parts get at least two just in case something like
this happens.
 

Mike_2545

Super Moderator
I have heard of letting the "factory smoke" out but this is the first time I have heard of "factory sound" being released. :)
 

kchriste

New Member
Forum Supporter
What was the load? If you had a unclamped inductor, such as an anti-thump relay on the output, it could spike and blow the regulator. Post the entire circuit including the load.
 

Sceadwian

Banned
Cause it to actually explode though? You need quiet a bit of energy to do that. I wanna see pictures =)
 

kchriste

New Member
Forum Supporter
What I was thinking was that the back EMF from the coil on the output could trigger the regulator to latch up, or otherwise fault out, causing it to draw excess power from the main input supply:
Coil EMF = blasting cap
15V supply = TNT :D
 

tcmtech

Banned
Most Helpful Member
I got your back on this one Triode!

I have seen so many IC's and electronic devices blow up that I know its a normal occurance. The plastic cases on the cheap IC's usualy just melt and smoke but the better ones will build up enough internal pressure to actualy pop the IC body open!

It could be from being improperly connected or an over voltage or power spike came from some where or its entirely possible it just did not want to live any longer.

If you want to see and hear a good IC explosion you should be around when a 1200 volt 200 amp IGBT half bridge block gives up on life! :D

Your regulator IC gave up at a few watts, Power IGBT's give up at a few 10's of kilowatts! :eek:
 

Speakerguy

Active Member
I've been in this business several years, and I can't think of one occurence where something was faulty from the factory. Everything that blew up turned out, in some fashion or another, to be my fault.

Electronics work. If you are buying from a reputable source and a decent semi manufacturer, it is 99.9% most definitely something you are doing. I say this knowing that I've sworn it was the part many times before - I just always found out it was me in the end.
 

tcmtech

Banned
Most Helpful Member
When I worked for a welding supply company as a service tech I know there were several welder and Plasma cutter manufacturers recalls related to "Unexplaned Device Failure" of specific IC's or switching devices due to poor manufacturing on the part of the IC or component manufacturer.
When you buy one or two you dont hear about it. When you buy 10 or 20 thousand they let you know!
 

Leftyretro

New Member
I've been in this business several years, and I can't think of one occurence where something was faulty from the factory. Everything that blew up turned out, in some fashion or another, to be my fault.

Electronics work. If you are buying from a reputable source and a decent semi manufacturer, it is 99.9% most definitely something you are doing. I say this knowing that I've sworn it was the part many times before - I just always found out it was me in the end.
When I was in the Air Force we had a name for this diagnosis, "short between the headsets".

Lefty
 

Triode

Active Member
Turns out it was a defect, but it wasn't the regulator or the power supply. Several of the rows on the breadboard were shorted together. After a lot of confusion testing this point and that and getting odd results, I tested the board itself and found that there were connections between holes where there shouldn't be. peeling off the backing I found a stray bit of rail material squashed flat under the backing. Chances are its one of the ones I got from a surplus place for $2. I guess you get what you pay for.

If anyone still wants to see pictures of the blown up regulator or the messed up breadboard I could put some up for you.

Thanks for all the input and advice.

I still find it a bit odd that just shorting a regulator would make it blow up like that but it is what it is. It really only blew off one piece, its a TO-220 package, and it basically fired a chunk consisting of most of the front half of the plastic case across the room, lucky it didn't hit my eye.
 

killivolt

Well-Known Member
Capacitors kur ...boom.

I had my boss hook a 1µ cap in backwards once. WoW:eek:

I was standing their when he did and for some reason it was my fault (just) for standing there. ;) Right.

It blew the lid off it and it went zinging past my head almost hit me in the eye.

Most of the time when stuff like that happened elsewhere in manufacturing and development, it was usually smoking and sizzling.

kv:D
 

kchriste

New Member
Forum Supporter
It IS odd since the 78xx series should have thermal and current limiting built in.
 

Sceadwian

Banned
Since you've fixed the problem, please post images of the fault.
 

killivolt

Well-Known Member
If anyone still wants to see pictures of the blown up regulator or the messed up breadboard I could put some up for you.
.
But of Course we would.;)

kv
 

creakndale

New Member
28 years ago, when I was in Tech school, we were given components (transformer, 4 diodes, capacitors, etc.) to build a rectifier. For safety, we had a Variac to "slowly turn up the AC" so you could watch and record the waveforms from a scope. As we cranked up the Variac, the waveform didn't look right. So cranked it up further and POW! One of diodes split in two.

Instructor comes running over. Looks at the circuit and sees nothing wrong with the polarity, wiring, etc. Put in a new diode and this time the instructor cranks up the Variac and POW! The new diode splits in two. Other students come over. This is exciting. Instructor rubbing his chin, his brain spinning. After about a minute he figured it out.

The scope ground lead was not connected to circuit ground but to the cathode of one of the diodes. However, the scope ground lead was forced to ground through the 3rd (ground) prong of the AC plug through the scope chassis.

Just then another POW! was heard across the room. Instructor says to me, "Go tell him what he's doing wrong". Then another POW! The lab experiment was stopped and the instructor gave us a lecture about Test Equipment and Grounding. Having the lecture before the lab might have saved a few diodes.

creakndale
 
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