From: John Tserkezis 
Reply-To: Fidonet AVtech Echo 

Bob Lawrence wrote:
>>So... I bought one of those positive-ion generators

> JT> Negative ion?

>  Does it matter?

  I imagine it would give you more 'reach' into the room.  That's why they 
specify pins (the sharp things that prick you in the middle of the night) as 
the output interface into the atmosphere.
  You are spewing out electrons after all.

>  Chicken...*OF COURSE* I had a limiting resistor! ROFL! It was the
> idea of all those diodes and capacitors directly on the mains that
> worried me. If one fails, they go one after the other. The Jacob's
> ladder falls over.

  Spoilsport.  You take all the fun out of it.  BTW, you get a little better 
performance if you leave out that limiting resistor- giving you a low impedance 
output to the surrounding air.

> JT> Stupid thing is, if you DIY, or buy the kit, they give you a
> JT> standard garden variety resistor, which arcs over at a couple
> JT> of hundred volts.

>  I thought a standard resistor was rated at 250 AC. Oh! You mean the
> one at the HV end... it's better than nothing.

  The stupid thing is, that many AREN'T good enough for mains operation.  Power 
supply filter bleed resistors are commonly garden variety, and fail on 
occasion.  Using high voltage types improves reliability, and cost, so it might 
matter if you're doing a million of them.

> JT> The theory of operation is that they cause the dust in the air
> JT> to clump together (static) which would make the heavy enough to
> JT> fall to the floor, where you vacuum them up again, let them
> JT> pass straight through the filter and back into the room again.
> 
>  It doesn't matter what theory you use (or invent) it's bullshit anyway. 

  Now now, that bullshit speculation has yet to be proven wrong.  Yet.  Until I 
can be bothered to pull my finger out, ask the whereabouts of our dust monitor 
and actually test this, they can be classed as "maybe" operational.

> JT> If you're vacuuming for dust removal, you're fucking kidding
> JT> yourself.

>  Vacuuming works to some extent. There is a dust filter... in fact,
> the new HEPA filters are *very* effective.

  Have you seen an effective improvement over a noral vacuum by using a dust 
monitor, or did you read the promotional blurb?
  I read promotional blurb, (it's all bullshit).  I wrote promotional blurb 
too, (it's also bullshit).  It's written with the proviso that utlimately, the 
guy who's reading it, will want to actually buy it after reading it.

> JT> We have a dust monitor at work that we occasionally have a
> JT> chance to play with when clients don't have it, and we log the
> JT> offices overnight. Airborne dust is low, at about 7:30pm, the
> JT> cleaners come in with their industrial strength vacuum
> JT> cleaners, kick up a dust storm from hell, and it takes the next
> JT> four hours for the levels to settle down again. 
> 
>  Yair... but if you measure *total* dust before and after, there is
> less after vacumming.

  Can also be said that there is the same *airborne* dust levels after it's 
settled.
  Although, the *important* thing is how much *airborne* dust exists after it's 
kicked around under *normal use* (walking around etc).
  Vacuuming removes a lot of it, but kicks up such a stink that makes it quite 
significantly worse (for about 2-4 hours) than "normal" kickaround levels.

  On average, it's better to vacuum, than not to, becuase eventually the dust 
levels will eventually accumilate to absolutely stupid levels, that normal 
movement within the room will make it worse than not vacuuming.

  My point is that there are *better* ways than vacuuming to remove the dust.

> JT> If anyone claims their "special" vacuum cleaner stops dust as
> JT> well, they're full of shit. Or they have a sub-micron filter
> JT> that blocks after 2 minutes of use. After which point your damp
> JT> rag would pick up more dust. And it's cheaper. And it uses less
> JT> power.
> 
>  HEPA filters rely on static. Dyson started the big change, now
> they're all doing it. They're still pretty useless...

  Static works as long as there is no significant airflow to blow it away from 
the attraction point.  The back of your television works quite well.  You just 
have to remember to clean it out every so often....
  A "vacuum cleaner' by it's very own purpose uses high air flow, defeating the 
purpose.  Even if they do use a venturi (or whatever) effect to confine 
particles to a containment area.  Works great for bits of paper in the 
demonstration, but pointless for stuff that you actually WANT to suck up.

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