ELF detector

L

Larry

Guest
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry
 
Larry wrote:
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry
Click to expand...
Use an opamp with low 1/f noise, and a loop antenna.
 
I read in sci.electronics.design that Robert Baer
<robertbaer@earthlink.net> wrote (in <41552C6E.661306FF@earthlink.net>)
about 'ELF detector', on Sat, 25 Sep 2004:
Larry wrote:

Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry

Use an opamp with low 1/f noise, and a loop antenna.
Click to expand...
And a Pixie tube, of course.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
gemlover@tampabay.rr.com (Larry) wrote in message news:<13667c89.0409242355.764c64f2@posting.google.com>...
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry
Click to expand...
A 100W light bulb does a good job for me. Its sensitivity extends
all the way to 60Hz, in fact.

Tim.
 
In article <13667c89.0409242355.764c64f2@posting.google.com>,
Larry <gemlover@tampabay.rr.com> wrote:
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
Click to expand...

The zero on the bottom end of the range can be trouble.

You can get GMRs from Digikey.

--
--
kensmith@rahul.net forging knowledge
 
In article <41552C6E.661306FF@earthlink.net>,
Robert Baer <robertbaer@earthlink.net> wrote:
Larry wrote:

Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry

Use an opamp with low 1/f noise, and a loop antenna.
Click to expand...
You didn't give enough details. How big does the loop have to be to do
the "0-" part of the range?


--
--
kensmith@rahul.net forging knowledge
 
"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:cj42mn$243$1@blue.rahul.net...
In article <13667c89.0409242355.764c64f2@posting.google.com>,
Larry <gemlover@tampabay.rr.com> wrote:
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.


The zero on the bottom end of the range can be trouble.
Click to expand...

I think that can be fixed with suitable software.

Ed
wb6wsn
 
"Tim Shoppa" <shoppa@trailing-edge.com> wrote in message
news:bec993c8.0409250915.3babcb6d@posting.google.com...
gemlover@tampabay.rr.com (Larry) wrote in message
news:<13667c89.0409242355.764c64f2@posting.google.com>...
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry

A 100W light bulb does a good job for me. Its sensitivity extends
all the way to 60Hz, in fact.

Tim.
Click to expand...

Older hams know that 100 Watt light bulbs have a frequency response to at
least 50 MHz! But they must roll off badly above 1 GHz, because they never
show the power I'm really putting out!

Ed
wb6wsn
 
In article <lAk5d.68220$9Y5.61521@fed1read02>,
Ed Price <edprice@cox.net> wrote:
"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:cj42mn$243$1@blue.rahul.net...
In article <13667c89.0409242355.764c64f2@posting.google.com>,
Larry <gemlover@tampabay.rr.com> wrote:
Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.


The zero on the bottom end of the range can be trouble.


I think that can be fixed with suitable software.
Click to expand...
I doubt software can do it. You need to divide by zero. Most programmers
have a hard time writing code that does that successfully.

--
--
kensmith@rahul.net forging knowledge
 
I read in sci.electronics.design that Ken Smith
<kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.
Click to expand...
IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
Ken Smith wrote:
In article <41552C6E.661306FF@earthlink.net>,
Robert Baer <robertbaer@earthlink.net> wrote:
Larry wrote:

Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry

Use an opamp with low 1/f noise, and a loop antenna.

You didn't give enough details. How big does the loop have to be to do
the "0-" part of the range?

--
--
kensmith@rahul.net forging knowledge
Click to expand...
Depends on the sensitivity you want.
Obviously, you cannot make a loop any where near 1/4 wavelength...
 
John Woodgate wrote:
I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
Click to expand...
ORDER??????????
What is *that*??
 
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:bkJTvRCl5mVBFwXa@jmwa.demon.co.uk...
I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
Click to expand...

Precisely, solved in Basic, circa 1968!
Or in Fortran, even earlier!
That's how coders solve those pesky little "special cases". <g>

Ed
wb6wsn
 
I read in sci.electronics.design that Robert Baer
<robertbaer@earthlink.net> wrote (in <4156705F.31F860EE@earthlink.net>)
about 'ELF detector', on Sun, 26 Sep 2004:
John Woodgate wrote:

I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

ORDER??????????
What is *that*??
Click to expand...
Ask your friendly local Marine sergeant.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
I read in sci.electronics.design that Ed Price <edprice@cox.net> wrote
(in <q0v5d.74623$9Y5.54225@fed1read02>) about 'ELF detector', on Sun, 26
Sep 2004:
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:bkJTvRCl5mVBFwXa@jmwa.demon.co.uk...
I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk


Precisely, solved in Basic, circa 1968!
Or in Fortran, even earlier!
That's how coders solve those pesky little "special cases". <g

There's a bit more to it. My pseudocode produces an extreme outlier
Click to expand...
result, which the user really ought to pick up. It does NOT produce an
error message that stops the program. Of course it can be extended to
produce a *warning*. Stopping the program for a recoverable error is,
IMHO, really rather stupid.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Sun, 26 Sep 2004 09:38:15 +0100, the renowned John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Ed Price <edprice@cox.net> wrote
(in <q0v5d.74623$9Y5.54225@fed1read02>) about 'ELF detector', on Sun, 26
Sep 2004:

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:bkJTvRCl5mVBFwXa@jmwa.demon.co.uk...
I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk


Precisely, solved in Basic, circa 1968!
Or in Fortran, even earlier!
That's how coders solve those pesky little "special cases". <g

There's a bit more to it. My pseudocode produces an extreme outlier
result, which the user really ought to pick up. It does NOT produce an
error message that stops the program. Of course it can be extended to
produce a *warning*. Stopping the program for a recoverable error is,
IMHO, really rather stupid.
Click to expand...
Note that you've arbitrarily chosen to use a very large positive
number for the result, even if the dividend is negative. I prefer math
that saturates in the appropriate direction. Sometimes, even with
division by zero errors, you can get it right. The sign tends to
matter quite a bit in control stuff.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
John Woodgate writes within:


There's a bit more to it. My pseudocode produces an extreme outlier
result, which the user really ought to pick up. It does NOT produce an
error message that stops the program. Of course it can be extended to
produce a *warning*. Stopping the program for a recoverable error is,
IMHO, really rather stupid.
Click to expand...
IF DIVISOR = 0 THEN PRINT "Division by 0!" ELSE RESULT = DIVIDEND/DIVISOR


[]s
--
Chaos MasterŽ, posting from Brazil.
"Two of the most famous products of Berkeley are LSD and Unix. I don't think
that this is a coincidence." -- Anonymous
"I'd rather be hated for who I am, than loved for who I am not" - Kurt Cobain
"F*** you, pal. " -- Amy Lee

"STATUS: ELF and ORC signals detected on Tolkien (sp?) Ring network!"

The Evanescen(t/ce) HP: http://marreka.no-ip.com
 
I read in sci.electronics.design that Chaos Master <spammers.fuck@spam.c
om.INVALID> wrote (in <MPG.1bc0c555d40b9c8398973d@news.individual.net>)
about 'ELF detector', on Sun, 26 Sep 2004:
John Woodgate writes within:


There's a bit more to it. My pseudocode produces an extreme outlier
result, which the user really ought to pick up. It does NOT produce an
error message that stops the program. Of course it can be extended to
produce a *warning*. Stopping the program for a recoverable error is,
IMHO, really rather stupid.

IF DIVISOR = 0 THEN PRINT "Division by 0!" ELSE RESULT =
DIVIDEND/DIVISOR
Click to expand...
But that overflows the column in a table of results, and is liable to
scramble the whole rest of the print-out. I speak from experience! (8-O(
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Sunday 26 September 2004 12:23 am, John Woodgate did deign to grace us
with the following:

I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Click to expand...
Gee, John, do you still punch your Fortran onto Hollerith cards?

;-)
Rich
 
"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:SFdBncC3znVBFwEZ@jmwa.demon.co.uk...
I read in sci.electronics.design that Robert Baer
robertbaer@earthlink.net> wrote (in <4156705F.31F860EE@earthlink.net>)
about 'ELF detector', on Sun, 26 Sep 2004:
John Woodgate wrote:

I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj4o62$g7l$8@blue.rahul.net>)
about 'ELF detector', on Sat, 25 Sep 2004:

I doubt software can do it. You need to divide by zero. Most
programmers have a hard time writing code that does that successfully.

IF DIVISOR = 0, THEN RESULT = 1E+38 ELSE RESULT = DIVIDEND/DIVISOR

It's the order in which you write it that matters. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

ORDER??????????
What is *that*??

Ask your friendly local Marine sergeant.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
Click to expand...
Friendly?

Charles
 
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