It's Smoke that makes it all work

[Terry_VK5TM]

Came across this yesterday that shows that it is Smoke that makes electronics work (seriously, it is in the GE Electronics Components Hobby Manual from 1965 )

(And could someone please point to the post showing how to put pictures inline instead of as attachments, my search foo is seriously failing today, thanks.)

[hannahs radios]

That's just too funny for words terry thanks for posting

[Argus25]

What a great graph.

It's along the lines that the problem with electronic parts is that they have defective smoke seals, because everyone observes that when the smoke leaks out, they stop working.

I have a Heathkit robot that can talk as it contains the Votrax SC-01A speech synthesiser IC. It is pre programmed with a number of sayings, phrases and songs:

"Smoking transistors is hazardous to my health"
"I have the utmost confidence in this mission Dave"

Are just some of them.

[Argus25]

I remember about thinking of the issue of reverse breakdown in the past because there are a number of publications explaining the severe destruction when it happens. However it isn't always. It depends on the product of voltage, current and time whether or not the junction spectacularly melts and it goes up in a puff of smoke, after all this is how Zener diodes work. You will notice though that Zener diodes over 100V are becoming difficult to get, when zenered just 100mA will cook them quickly.
There was once made a spectacular stud mounted 400V Zener, made by Lucas semiconductors, to protect the collector circuit of a transistor switching an ignition coil. They are so rare now I only have one in my collection and they never appear as a separate item for sale. Manufacturers wised up and use much less robust zeners between the collector and base of the output transistors, turning those in an active power clamp instead.

[Dave Moll]

Originally Posted by Terry_VK5TM

(And could someone please point to the post showing how to put pictures inline instead of as attachments, my search foo is seriously failing today, thanks.)

I'm not sure where there is a post, but it can be achieved by attaching the image as normal, then inserting into the text [attach]attachment ID[/attach]. The ID can be found by hovering over the attachment after uploading.

[Nuvistor]

There are instructions at the bottom of this FAQ.
https://www.vintage-radio.net/forum/...l&titlesonly=0

[joebog1]

Image test

That was my file name to "test" this answer.
Is this some Windows magic??

quote:

'm not sure where there is a post, but it can be achieved by attaching the image as normal, then inserting into the text [attach]attachment ID[/attach]. The ID can be found by hovering over the attachment after uploading.

Unquote:

I dont know where you got that info from ??
Sorry, this is a genuine question.

With respect

Joe

[joebog1]

That MUST be Windows stuff!!. I cant even get to that "position".

Soory mods

Joe

[Beardyman]

It is very illustrative of the consequences & I can see it would get the point across in a memorable way!
Here's one of my favourites if you like a bit of fun with the sometimes very dry subject of electronics. If the admins feel it is inappropriate please feel free to delete.

[KeithsTV]

In order to maintain job security, physicists strive to make electronic theory complicated. To this end, they devised a cock and bull story to do with atoms and electrons and how they were responsible for electrical behaviour.

However, in a secret document leaked from the National Physics Lavatory, it has finally been revealed that an electrical current is, in fact, a flow of smoke. This is supported by the fact that when smoke escapes from electrical equipment then that equipment seldom works any more.

Keith

[G6Tanuki]

And if you break open an old-style zinc-carbon battery, it's all black inside - that's concentrated smoke!

[boxdoctor]

Sometimes one even gets a bonus "fragrance" , as with Selenium rectifiers.
This is all easy tech though, compared to the theory behind Dark suckers! to which, I am sure post #8 is making a cryptic refence . Tony.
http://web.mit.edu/kolya/misc/txt/dark_suckers

[kalee20]

Originally Posted by Terry_VK5TM

Came across this yesterday that shows that it is Smoke that makes electronics work (seriously, it is in the GE Electronics Components Hobby Manual from 1965 )

It's the sort of thing that Tektronix would have done, too. See below!

Electronics is fun, Fun, FUN!!

[Dave Moll]

Originally Posted by joebog1

quote:

I'm not sure where there is a post, but it can be achieved by attaching the image as normal, then inserting into the text [attach]attachment ID[/attach]. The ID can be found by hovering over the attachment after uploading.


Unquote:

I dont know where you got that info from ??
Sorry, this is a genuine question.

With respect

Joe

And with respect, it was a genuine answer based on experience.

as demonstrated above.

[Radio Wrangler]

Extra caution is needed. Reverse bias avalanche of a PN junction - especially a base-emitter junction can do damage even before the smoke release point. For transistors, you'll find a progressive reduction in gain and an increase in noise factor. Not as dramatic, but still worth avoiding. Maybe the smoke stays in, but gets contaminated?

David

[broadgage]

Originally Posted by Radio Wrangler

Extra caution is needed. Reverse bias avalanche of a PN junction - especially a base-emitter junction can do damage even before the smoke release point. For transistors, you'll find a progressive reduction in gain and an increase in noise factor. Not as dramatic, but still worth avoiding. Maybe the smoke stays in, but gets contaminated?

David

Semi-conductors contain magic smoke. The escape of small volumes of this magic smoke is much less noticeable than the common smoke found in motors and transformers.

[Terry_VK5TM]

Thanks for the picture attachment replies, I'll give them a try next time (and the other replies, glad it bought a smile to the dial )

[Herald1360]

Originally Posted by Beardyman

It is very illustrative of the consequences & I can see it would get the point across in a memorable way!
Here's one of my favourites if you like a bit of fun with the sometimes very dry subject of electronics. If the admins feel it is inappropriate please feel free to delete.

The relevant part in this circuit is ringed below.

Smoke analysis apparently also features in some circuit simulators such as Microcap.

[julie_m]

Originally Posted by Radio Wrangler

Reverse bias avalanche of a PN junction - especially a base-emitter junction can do damage even before the smoke release point. For transistors, you'll find a progressive reduction in gain and an increase in noise factor.

BC547s seem to be cool with this. The old Glow-Worm Combi boiler (the one that has to run the fan on half speed all the time, just to keep the pilot burner alight! How anyone can have the gall to talk about leaving a mobile phone charger plugged in .....) used to shove 24V AC almost straight into the base of one.

LEDs in cheap kettles also spend time in reverse breakdown.

[Argus25]

Originally Posted by Radio Wrangler

Extra caution is needed. Reverse bias avalanche of a PN junction - especially a base-emitter junction can do damage even before the smoke release point. For transistors, you'll find a progressive reduction in gain and an increase in noise factor. Not as dramatic, but still worth avoiding. Maybe the smoke stays in, but gets contaminated?

David

One thing about this the effects are seldom seen but in two places I know of.

The audiophiles complain that in their amplifiers with BJT based IC's, with coupling capacitors between stages, that sometimes with power cycling the IC's get degraded over time as from time to time the B-E junctions of the input devices in the IC get degraded. Sometime they recommend replacing all the IC's in an amp for this reason. I have never been able to hear the effect of this myself.

The other example that happens is in the simple common 2 transistor multivibrator circuit. If it is powered by more than 7V the B-E junctions Zener on each half cycle , it's easy to see on a scope on the capacitor's charging waveform at the base of the transistor. This does relentlessly damage the transistor and after some time the multivibrator will not start as the transistor's hfe gets progressively lower. This is an effect I have seen in an instrument.

Motorola wrote a paper on the effect of hfe degradation of transistors after zenering their B-E junctions, as I recall the exact mechanism of it remained speculative.

I think there is an application for it though. If two transistors require an exactly matched hfe, the one with the higher hfe could be treated with some pulses of breakdown to lower it until it exactly matched the other transistor.

Of course it doesn't matter if an LED or some diode gets zenered, as long as the dissipation is low, because there is no hfe issue to contend with. The big evil of it is for a power supply rectifier because the circuit impedances are low, the breakdown voltages are high and the reverse breakdown currents are high, so the device goes boom when a voltage spike comes along and its piv gets exceeded.