magnetic field

nospam · Sep 29, 2004

"Chris Cooper" <chrisnews@sc3.net> wrote:

Immediately after hammering the spikes into the soil, the resistance
measurement was at about 1k ... and rising slowly but steadily. And then I
reversed the probes and measured about 500 ohms, holding steady. So I
waited a day. Measuring one direction I got 1.5Mohms, the other direction
500kohm. Today it was 2.2Mohms one way and 1.5Mohms the other way.

What in the sam hill blazes is going on here? Some sort of weird chemical
reaction that makes the resistance different in one direction than the
other?

Not that weird - you made a battery - you can always call it a soil pH
meter

Commercial soil moisture measurements are made with probes inside (I think)
a gypsum block. They give a resistance reading which must be measured with
ac excitation (to avoid electrolytic action damaging the probes).

Search the web you will find information and suppliers.

Chris Cooper · Sep 29, 2004

Thanks, I had already searched the web and found several nice moisture
meters for about $300. That's (1) much more than I wanted to spend, and (2)
not nearly as interesting as trying to figure this out for myself (grin).

"nospam" <nospam@nospam.invalid> wrote in message
news:tt21ovgrtv1f21c17kbq315i748sfatvbb@4ax.com...

"Chris Cooper" <chrisnews@sc3.net> wrote:

Immediately after hammering the spikes into the soil, the resistance
measurement was at about 1k ... and rising slowly but steadily. And then
I
reversed the probes and measured about 500 ohms, holding steady. So I
waited a day. Measuring one direction I got 1.5Mohms, the other
direction
500kohm. Today it was 2.2Mohms one way and 1.5Mohms the other way.

What in the sam hill blazes is going on here? Some sort of weird
chemical
reaction that makes the resistance different in one direction than the
other?

Not that weird - you made a battery - you can always call it a soil pH
meter

Commercial soil moisture measurements are made with probes inside (I
think)
a gypsum block. They give a resistance reading which must be measured with
ac excitation (to avoid electrolytic action damaging the probes).

Search the web you will find information and suppliers.

nospam · Sep 29, 2004

"Chris Cooper" <chrisnews@sc3.net> wrote:

Thanks, I had already searched the web and found several nice moisture
meters for about $300. That's (1) much more than I wanted to spend, and (2)
not nearly as interesting as trying to figure this out for myself (grin).

I was not suggesting you buy a complete meter. I was suggesting you find
out what a decent probe is like here

http://www.microirrigationforum.com/new/sensors/gypsum.html

or here

http://www.irrometer.com/agcat.htm#watermark

that one is $30.

Spajky · Sep 29, 2004

On Sun, 5 Oct 2003 23:42:19 -0400, "Jerry G." <jerryg50@hotmail.com>
wrote:

If your Roland mixer is of high value to you, invest in a very good UPS.
The APC, and the Belkin units are very good. A surge protector is not very
good for serious protection.

As for anything of value, it is best to put a UPS on it. This way, it is
protected as much as possible for a reasonable cost.

has anybody thought about the signal coming from tha UPS (mostly non
sinus wave when internal electronics works when there is no
electricity) when bridging electrical fall outs?

the PSU of the mixer maybe would not like it! Try before you buy!
maybe the simple enough powerfull surge protector with RF filter build
in would do better, but all equipment connected to a mixer should be
supplyed also thru this surge protector IMHO ...

electrical dropOuts IMHO would not harm equipment but spikes when
electricity comes back will ... capacitors inside equipment PSUs can
hold in idle almost a second power dropout if well designed ...

-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Chris Cooper · Sep 29, 2004

Aha! That's much more within the budget!

It looks like I'm dealing with a slightly different process here? What I
have right now, is two "probes" with 3' of earth between them, and I was
trying to measure the resistance between them. The probes you pointed out
both have two wires coming out, which makes me think that I only need one
probe (not two) per area to be measured? And so instead of measuring the
ground moisture, I'm actually measuring the moisture in the probe? Which
should be "closely related" to the moisture level in the surrounding soil?
That's fine, by the way, I just want to make sure I understand what I'm
doing!

Thanks,
Chris

"nospam" <nospam@nospam.invalid> wrote in message
news:04g1ovcormunqcph5aphbgbdaiqiqhlma2@4ax.com...

"Chris Cooper" <chrisnews@sc3.net> wrote:

Thanks, I had already searched the web and found several nice moisture
meters for about $300. That's (1) much more than I wanted to spend, and
(2)
not nearly as interesting as trying to figure this out for myself (grin).

I was not suggesting you buy a complete meter. I was suggesting you find
out what a decent probe is like here

http://www.microirrigationforum.com/new/sensors/gypsum.html

or here

http://www.irrometer.com/agcat.htm#watermark

that one is $30.

nospam · Sep 29, 2004

"Chris Cooper" <chrisnews@sc3.net> wrote:

Aha! That's much more within the budget!

It looks like I'm dealing with a slightly different process here? What I
have right now, is two "probes" with 3' of earth between them, and I was
trying to measure the resistance between them. The probes you pointed out
both have two wires coming out, which makes me think that I only need one
probe (not two) per area to be measured? And so instead of measuring the
ground moisture, I'm actually measuring the moisture in the probe? Which
should be "closely related" to the moisture level in the surrounding soil?

Basically yes - go search the web there is a fair amount of information to
be found.

Gordon · Sep 29, 2004

Chris this is what I did.
Five years ago I started where you are now but I used 3" lengths of 1/8"
brazing rod spaced at 1/2" and buried 4" below ground. The probes are
connected via twisted pair to the PC. The hard part is overcoming noise
generated by ground currents. 50hz and its harmonics in my neck of the
woods.
I tried low voltage AC and a whetstone bridge but couldn't get reliable
readings with multiple sensors and large ground currents. Maybe I did
something wrong.
After some very good ideas from s.e.d I applied near AC from an osc (using
the +&- 12V rails of the PC) to the probes and used a full wave rectifier
and averaging filter (national an20 page 10) to feed DC levels to an ADC in
the PC.
This has been a stop start project since I installed the probes 5 years ago
and I've only recently got it up and running but the probes are still in
good shape.
I think the gypsum probes I've read about would be better as they should
overcome the conductivity differences of soil types.
Gordon
my address needs gj in front for mail

Chris Cooper <chrisnews@sc3.net> wrote in message
news:3f81ab30$0$196$75868355@news.frii.net...

That certainly is easier ... the problem is, when I said I only want to
test
it once a day, what I want to do is to hook up my PC so _it_ tests it once
a
day - so it's not that I want to run outside once a day and stick the
probes
into the soil, the probes gotta stay there...

"Bushy" <please@reply.to.group> wrote in message
news:bls2aj$cfa$1@bunyip.cc.uq.edu.au...
Forget the longwinded approach and simply use two different metal probes
and
a simple volt meter.

The cheap shop moisture probe I have uses this circuit and has two
different
metals separated by an insulator like coax cable and a half inch long
pointed copper tip. The shaft is silver coloured but I'm not sure what
metal
it is.

There are different voltages produced between different metals in a salt
solution and the moisture level in the soil will cause the voltage
produced
to change.

Drawback is the probe will corrode, but if you only want to test it once
per
day it is easy. Stick the 1/4 inch diameter 12 inch long probe into the
soil
and look at the attached meter.

It cost me less than $5.00 Australian and is now about five years old.
It
works happily for my girlfriend's pot plants but I don't know how
accurate
it is. It does show a difference when it's wet to when it's dry but I
think
different soils would have different salt levels which would cause
calibration problems.

Hope this helps,
Peter

Richard Crowley · Sep 29, 2004

Richard Crowley wrote:

Rein Wiehler" wrote ...
whats this guy doing, advertising his company

Never seen a canned sig before?

on a german language news group?

Crossposting is a new concept to you? :-0

"Lars Mueller" wrote ...

Maybe not to him, buy obviously to you because you don't
know that you should take care about the contents of every
group and set a F'up2. This includes the use of the correct
language.

Since you crossposted your English language response to the
sci.electronics.de group, apparently you either think it is OK
or else you violated you own rule? (Following up to s.e.m
only as per your tag.)

My point wasn't that the OP was right (or wrong), but that
it appeared to be originated from an English newsgroup(s)

We see occasional German, Spanish, French, etc. postings
in English newsgroups. No big deal. If you read the language,
fine. If not, ignore it. Not worth making a high-court case
of it.

Inclusion of one's employers URL in your signature file
doesn't constitute "advertising" to most people who have
been around Usenet for longer than a few months.

Chris Hodges · Sep 29, 2004

"Richard Crowley" <rcrowley7@xprt.net> wrote in message
<snip>

We see occasional German, Spanish, French, etc. postings
in English newsgroups. No big deal. If you read the language,
fine. If not, ignore it. Not worth making a high-court case
of it.

Many of the "English" groups aren`t really "English, but international
- most of the discussion is in English but that`s all (unless of
course the charter for the ng specifies a language - not common).

Chris

Richard Crowley · Sep 29, 2004

"Chris Hodges" <chrisjhodges@yahoo.com> wrote in message
news:d36a713e.0310072131.36406ba9@posting.google.com...

"Richard Crowley" <rcrowley7@xprt.net> wrote in message
snip
We see occasional German, Spanish, French, etc. postings
in English newsgroups. No big deal. If you read the language,
fine. If not, ignore it. Not worth making a high-court case
of it.

Many of the "English" groups aren`t really "English, but international
- most of the discussion is in English but that`s all (unless of
course the charter for the ng specifies a language - not common).

"The length of this conversation has exceeded my
interest in it." -- Casey McCall in "Sports Night"

Blank Slate · Sep 29, 2004

They have crossed beef genes with grapefruit. There is no blood and
when the fruit is ripe it;s sliced like beef or burgers. It will be
available next year in trial markets. No harsh conditions in a tree.
They also have grown it in trays in doors in slabs, but the tree fruit
sounds better.

All for meat with out faces or bones!

On Wed, 08 Oct 2003 05:18:42 GMT, "Ross Mac"
<macroeng@example.invalid> wrote:

43....huh....could fool me.....and an engineer...hmmmm...what field???......
Ya wonder bout me??? I am retired.....I made my fortune a few years back in
electronics.....
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:rh57ovo9520n2jj5u7gi5daetioto31mi8@4ax.com...
On Wed, 08 Oct 2003 02:49:59 GMT, "Ross Mac"
macroeng@example.invalid> Gave us:

Here we go again.....Tard Boy claims to be 43....yeah right...and his
vocabulary...yup...the same....retard and dipshit...and his reference to
school friends....well like I said...Tard Boy is in school.....hope the
little bastard learns something!

I am 43. I am an engineer, ya fuckin' 'tard.

Like I said... I have done more in the past week to make the world
a better place for mankind, than your lame, wussy boy ass will ever do
in your ENTIRE lame, pathetic cringing little milksop life.

You totally clueless bastard.

BretCahill · Sep 29, 2004

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

Jim Thompson · Sep 29, 2004

On 10 Oct 2003 02:28:14 GMT, bretcahill@aol.com (BretCahill) wrote:

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

I've never seen a pet peeve... are they a friendly animal ?

480)460-2350 | |
| E-mail Address at Website Fax

Ken Taylor · Sep 29, 2004

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:qo6cov0im7lghe8kjtg66ie7021bqknko4@4ax.com...

On 10 Oct 2003 02:28:14 GMT, bretcahill@aol.com (BretCahill) wrote:

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

I've never seen a pet peeve... are they a friendly animal ?

...Jim Thompson
--
My pet peeved on my good jacket - I wasn't impressed!

Ken

Jim Thompson · Sep 29, 2004

On Fri, 10 Oct 2003 15:50:20 +1300, "Ken Taylor" <ken123@xtra.co.nz>
wrote:

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:qo6cov0im7lghe8kjtg66ie7021bqknko4@4ax.com...
On 10 Oct 2003 02:28:14 GMT, bretcahill@aol.com (BretCahill) wrote:

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

I've never seen a pet peeve... are they a friendly animal ?

...Jim Thompson
--
My pet peeved on my good jacket - I wasn't impressed!

Ken

I've never had a pet peeve on my jacket, but with four children and
now six grandchildren, I've always had a baby-barf-yellow stain over
the left shoulder of my jacket ;-)

I got so I liked the color so well I almost bought a 280Z of that
color, but my wife said no.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Ken Taylor · Sep 29, 2004

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:0q7cov0fo642gushujhuhe7bjg6a31mn2e@4ax.com...

On Fri, 10 Oct 2003 15:50:20 +1300, "Ken Taylor" <ken123@xtra.co.nz
wrote:

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:qo6cov0im7lghe8kjtg66ie7021bqknko4@4ax.com...
On 10 Oct 2003 02:28:14 GMT, bretcahill@aol.com (BretCahill) wrote:

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

I've never seen a pet peeve... are they a friendly animal ?

...Jim Thompson
--
My pet peeved on my good jacket - I wasn't impressed!

Ken

I've never had a pet peeve on my jacket, but with four children and
now six grandchildren, I've always had a baby-barf-yellow stain over
the left shoulder of my jacket ;-)

I got so I liked the color so well I almost bought a 280Z of that
color, but my wife said no.

...Jim Thompson

Well, your wife has good taste in cars, anyway.

Ken

Jim Thompson · Sep 29, 2004

On Fri, 10 Oct 2003 16:23:58 +1300, "Ken Taylor" <ken123@xtra.co.nz>
wrote:

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:0q7cov0fo642gushujhuhe7bjg6a31mn2e@4ax.com...
On Fri, 10 Oct 2003 15:50:20 +1300, "Ken Taylor" <ken123@xtra.co.nz
wrote:

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:qo6cov0im7lghe8kjtg66ie7021bqknko4@4ax.com...
On 10 Oct 2003 02:28:14 GMT, bretcahill@aol.com (BretCahill) wrote:

Digressing a little is OK but when you
digress, change the title to reflect the
new topic.

That's my pet peeve.

Bret Cahill

I've never seen a pet peeve... are they a friendly animal ?

...Jim Thompson
--
My pet peeved on my good jacket - I wasn't impressed!

Ken

I've never had a pet peeve on my jacket, but with four children and
now six grandchildren, I've always had a baby-barf-yellow stain over
the left shoulder of my jacket ;-)

I got so I liked the color so well I almost bought a 280Z of that
color, but my wife said no.

...Jim Thompson

Well, your wife has good taste in cars, anyway.

Ken

Oh, I got my Z, it just was silver ;-) In fact I had two, a 1977 and

480)460-2350 | |
| E-mail Address at Website Fax

BretCahill · Sep 29, 2004

Is aluminum too weak to wind into a coil or
WHAT?

? ? ?

Bret Cahill

DarkMatter · Sep 29, 2004

On 10 Oct 2003 04:49:25 GMT, bretcahill@aol.com (BretCahill) Gave us:

Is aluminum too weak to wind into a coil or
WHAT?

Finding aluminum wire with the proper, thin, high dielectric
coatings on it, for use in transformers, is going to be tough or a
special order item. Weak? No. Why use something that doesn't
perform as well though? I squared R losses. Also making high current
bonds to it is not as easy to do.

It will get hotter as well, reducing connection life, and raising
failure likelihood. Also, the few points of transformer efficiency
that are lost will be found in higher heat emission in the wire, and
greater power input requisites to get the same job done.

Why fuck with what works? Use Copper. You want special? Use Litz
wire, or silver plated copper mag wire, or get all silver wire, if you
dare to attempt such a special order case.

There are lots of wire makers that will make whatever you wish... at
a price. If it ain't "off the shelf" it ain't gonna be cheap.

JeffM · Sep 29, 2004

I'd try to match wits with Jim, but I'm only half-armed.

magnetic field

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