Component Damage

I'd first be mindful of mechanical damage from doing that. When was the book written? Germanium?

NT

Haha! I think even those old germanium diodes would easily cope with a four foot fall!

The original, point-contact trasnsistors from the 1950's were quite fragile devices, basically a pair of etched hair whiskers on a Germanium speck.

Supposedly, it is the tiny dust particles in an air stream that create the triboelectric charge. So, clean air should be better. I live in Missouri, so we have enough humidity that ESD is a fairly rare phenomenon. I have used vacuum cleaners to clean old computer gear, and never had damage, although I was concerned about the possibility.

I have seen a fat spark produced when firing off a CO2 fire extinguisher, which seemed like a pretty big design defect. They should have made the hose and nozzle with a static dissipative material.

Jon

I think those would be some of the more fragile items. Many have an extremely thin filament stretching a few mm with no support at all.

NT

I beg to differ. Air compressors totally *rock*! Having used one now for

7 years I could not imagine going back to *any* other method. Nothing else comes close.

I'd be more worried about the action of brushing itself giving rise to static charges. It's hard to know for sure what

Yes, been there; done that. In fact a gave a co-worker a pretty nasty shock by using a CO2 extinguisher which must have charged me up to 10s of thousands of volts whilst I put out a fire with it. It was a very noisy situation so I needed to shout into his ear to make myself heard and this terrific blue spark shot straight from my nose to his ear! Had no effect on me but sent him reeling. You should have seen the look on his face! :->

Oh, no; a point contact diode can easily jar out of spec. There was even an old device (the 'coherer') which reformed a rectifying contact by motorized shaking during normal operation.

Yeah, air is so expensive you gotta use it sparingly hehehe! The one caveat I would add about blasting boards with (clean) compressed air is that you *gotta* do it outdoors for all sorts of reasons I can't be assed to go into here.

You're certainly right - if you had used it around any sort of flammable vapors, the spark might have started a fire. ;-)

I'm not sure that would have helped. Where would the charge have gone, during the second or three that one was blasting away with CO2? There'd be only a very limited amount of charge flow back into the CO2 cloud (neither the CO2 nor the ice crystals which were triboelectrically active, will be particularly conductive), or dissipate into the air nearby. The major charge-sink would still be the body of the person wielding the extinguisher.

is interesting. Apparently, even aluminum can generate a charge via triboelectric effect, and it's about as static-conductive as you could ask for.

Dont try that with a vaccuum tube!

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

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I've used a 1KW handheld Martindale blower for decades, no known static problem ,just occassional physical breakage of shielding or something like that, because of the air pressure involved, blowing out tarry/greasy/hairy crud.

diodes would be OK but die mounting and bond wires in some germanium transistors was well, err - a bit amateurish.

Nowadays; suppliers pack *ANY* components in anti-static bags - it used to be some sort of clue which bits to handle with care.

There's some unexpected parts on the vulnerable list, so maybe they have a point.

molded semiconductors can be subjected to pretty much anything that doesn't break the case.

The first successful anti aircraft shell proximity fuze that could be fired out of a gun had 3 hearing aid style tubes.

The thyratron obviously isn't a hearing aid tube - its about the sixe & shape of the glass envelope.

AFAIK: the point is "burned in" during manufacture. The weld is pretty much the alloying process that creates the PN junction.

They're much less fragile than the old catswhisker/galena crystal.

I've seen one or two bounce - not very often though.

The one I fished out of a skip is now fitted with a tyre adaptor and used for blowing tubeless tyre onto the rim.

You have to hold it upside down - if the syphon tube puts liquid CO2 into the tyre, the rim starts creaking ominously.

Are you the same Ian Field that has authored several books on UHF/VHF subjects?

Plasma physics too...

oh sorry that was Ion Fields. :^)

George H.