straydog wrote:

Yep, I can vouch for this effect. I've seen it, too. Short the cap with
alligator clip-tipped wire for a few seconds if you want that voltage
down to microvolts. I think it is not "soak" but simple RC time constant
decay. Just like radioactive half-life. Residual voltage on a cap
_never_ goes to true zero, only according to the decay equation.
However, there is a so-called "electret" effect which really sounds like
your "soak" effect.

No, it's not a simple time constant -- the slope is much different. A
reasonably good model of it is a series R, shunt C, series R, shunt C,
etc. A large number of Rs and Cs with various time constants have to be
used to imitate it reasonably well.

I don't know about an "electret effect". An electret is a dielectric
with a permanently trapped charge, so it produces a static electric
field. It's the analog of a magnet, with permanently trapped flux and
producing a permanent magnetic field. A magnet that's not moving can't
produce a current (much to the dismay of the perpetual motion crowd),
and an electret that's not moving can't produce a voltage.


D'arsonval meters, especially sensitive ones, are also best stored with
a shorting wire accross the terminals.

That's for an entirely different reason -- to protect the meter from
damage, rather than the user.

Roy Lewallen, W7EL

From: straydog on Fri 15 Jul 2005 00:48


That's called trial and error. Or, try, smoke, fix. Like if ready, fire,
aim does not work, change the order to ready, aim, fire.

All electronics works on smoke. If the smoke leaks out,
it won't work...

On Thu, 14 Jul 2005, Roy Lewallen wrote:

Date: Thu, 14 Jul 2005 19:47:23 -0700
From: Roy Lewallen
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

straydog wrote:

Yep, I can vouch for this effect. I've seen it, too. Short the cap with
alligator clip-tipped wire for a few seconds if you want that voltage down
to microvolts. I think it is not "soak" but simple RC time constant decay.
Just like radioactive half-life. Residual voltage on a cap _never_ goes to
true zero, only according to the decay equation. However, there is a
so-called "electret" effect which really sounds like your "soak" effect.

No, it's not a simple time constant -- the slope is much different. A
reasonably good model of it is a series R, shunt C, series R, shunt C, etc. A
large number of Rs and Cs with various time constants have to be used to
imitate it reasonably well.

Well, if you want to get technical about it, yes. All those layers of foil
all, individually, add up to all of those Cs and Rs.

I don't know about an "electret effect". An electret is a dielectric with a
permanently trapped charge, so it produces a static electric field.

I doubt if there is very much in the universe with a real, practical
_permanence_. The second law of thermodynamics says that trapped charge is
going to try hard to become untrapped.

It's the
analog of a magnet, with permanently trapped flux and producing a permanent
magnetic field.

Most magnets that I've heard about will slowly lose their magnetism via
one of many mechanisms.

A magnet that's not moving can't produce a current (much to
the dismay of the perpetual motion crowd), and an electret that's not moving
can't produce a voltage.

In a laboratory, once, I made an electret out of, basically, frozen water.
The various pieces of these electrets, bathed in liquid nitrogen, behaved,
qualitatively, like little magnets. Bring one near another, and whatever
"pole" was at some point on one piece would spontaneously jump,
appropriately, to the piece I was holding.

An electret that is not moving can't produce a voltage? Semantics. There
_will_ be an electric field between one pole and the other and it _will_
be measureable and calculable and the results will be in volts regardless
of whether the electret is "moving". The units can be expressed in more
than one way depending on reference systems, definitions, and goal of the
measurement or calculation.


D'arsonval meters, especially sensitive ones, are also best stored with a
shorting wire accross the terminals.

That's for an entirely different reason -- to protect the meter from damage,
rather than the user.

For many people (since, in my life, it came up many times in
conversation), protecting the meter was more important.

Roy Lewallen, W7EL


Art, W4PON

On Fri, 14 Jul 2005 wrote:

Date: 14 Jul 2005 20:48:16 -0700
From:
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

From: straydog on Fri 15 Jul 2005 00:48


That's called trial and error. Or, try, smoke, fix. Like if ready, fire,
aim does not work, change the order to ready, aim, fire.

All electronics works on smoke. If the smoke leaks out,
it won't work...


;-) Reminds me of another joke I can't quite remember: something
dealing with the proof that electricity is really smoke, or something like
that. Maybe someone has a reference to that joke. It was pretty funny,
too.

Art, W4PON

All electronics works on smoke.
If the smoke leaks out, it won't work...

;-) Reminds me of another joke I can't quite remember: something
dealing with the proof that electricity is really smoke....

A local (and now retired) engineering faculty member has an after-dinner
speech in which he "proves" that "electricity is black and heavy"!

For example, in an automobile, electricity is stored in the battery.
What color is the battery? Black!
And it is quite heavy for its size.

And on and on and on!

--Myron.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

straydog wrote:



On Fri, 14 Jul 2005 wrote:

Date: 14 Jul 2005 20:48:16 -0700
From:
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

From: straydog on Fri 15 Jul 2005 00:48


That's called trial and error. Or, try, smoke, fix. Like if ready, fire,
aim does not work, change the order to ready, aim, fire.


All electronics works on smoke. If the smoke leaks out,
it won't work...


;-) Reminds me of another joke I can't quite remember: something
dealing with the proof that electricity is really smoke, or something
like that. Maybe someone has a reference to that joke. It was pretty
funny, too.

Art, W4PON

But electricity _is_ really smoke. They burn coal at the generating
station and it travels through the wires to your house, where it makes
everything work. Then the used smoke goes _back_ through the wires (why
do you think they call them "return" wires, eh?) to the generating
station where it goes up the smokestack.

If something should break then some of the smoke will leak out right
there in your house right before the thing stops working.

And that's how you know that electricity is smoke.

--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Fri, 15 Jul 2005, Tim Wescott wrote:

Date: Fri, 15 Jul 2005 16:51:21 -0700
From: Tim Wescott
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

straydog wrote:



On Fri, 14 Jul 2005 wrote:

Date: 14 Jul 2005 20:48:16 -0700
From:
Newsgroups: rec.radio.amateur.homebrew
Subject: QUESTION: Fun with Svetlanas or Staying alive with kV power
supplies

From: straydog on Fri 15 Jul 2005 00:48


That's called trial and error. Or, try, smoke, fix. Like if ready, fire,
aim does not work, change the order to ready, aim, fire.


All electronics works on smoke. If the smoke leaks out,
it won't work...


;-) Reminds me of another joke I can't quite remember: something
dealing with the proof that electricity is really smoke, or something like
that. Maybe someone has a reference to that joke. It was pretty funny, too.

Art, W4PON

But electricity _is_ really smoke. They burn coal at the generating station
and it travels through the wires to your house, where it makes everything
work. Then the used smoke goes _back_ through the wires (why do you think
they call them "return" wires, eh?) to the generating station where it goes
up the smokestack.

If something should break then some of the smoke will leak out right there in
your house right before the thing stops working.

And that's how you know that electricity is smoke.

That's pretty good, but I seem to recall another slightly different
version of the joke but with some really clever line about the purpose
of insulation (and a half-believable rationale [rationale does not mean
scientific, however). Anyone else remember more of the details of this joke?


Art, W4PON

--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Myron wrote:


A local (and now retired) engineering faculty member has an after-dinner
speech in which he "proves" that "electricity is black and heavy"!

For example, in an automobile, electricity is stored in the battery.
What color is the battery? Black!
And it is quite heavy for its size.


Sounds logical to me.

My favoite is the Dark Sucker Theory (light is the absence of dark, and
light bulds suck dark). Do a google on it for lots more info, probably more
than you ever wanted to know... :-)

And thusly another thread morphs far off topic...

But electricity _is_ really smoke. They burn coal at the generating
station and it travels through the wires to your house, where it makes ....

Did you notice that coal is BLACK? And most smoke is BLACK, too.

Insofar as water-generated electricity is concerned, it comes from rain
which has FALLEN (it's heavy) out of BLACK clouds and flowed downward
(heavy, again) to a sort of centrifuge which spins the HEAVY electricity
out of the water and forces it into the wires....
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)