Loran, GPS, Lightning, Timing
Lightning risetimes are slow enough that back-to-back zener diode limiters can
protect the input circuitry for a 1-meter probe. Nothing will stop a direct
strike, even a 12ax7 :-). A series resistor on the input helps. Actually, a
well-designed active probe antenna, even (shudder) one made by MFJ will be
quite adequate for vlf-ulf phenomena. May have a lo-pass filter that needs
attention.
Measuring the earth/s fair-weather field, 100 v/m or so, or even a field under
a thunderstorm, 5000v/m or higher, would require input impedance in excess of
10^15 ohm. Better is to raise a sharp point, say a sewing needle on a nice
protected teflon or better kel-f insulator, and measure the small current of
around 10 fA. Needs a small breeze to work right. Clean off the spider webs
and wasp nests as needed.
Better is to build a device called a field mill (q.v.) that essentially chops
the field into an AC signal.
Getting too far from time nuttery and into atmospheric electric nuttery :-)
Don
Brian Lloyd
On Wed, Jun 25, 2014 at 4:42 PM, paul swed paulswedb@gmail.com wrote:
I am currently using a 12AX7 as a ELF preamp and have for years.
A note in the coldest part of winter preheat the tube low filament voltage.
They tend to fracture.
It sits 200 ft from the house as far away in the woods as possible.
That said and back to the thread. At these frequencies tubes do work. The
12AX7 can be found on vlf.it and numbers of tubes will work. They run 12 V
on the plate. They also stand up to nearby lightning very well.
So Diddier now you have no excuse. I can't wait to implement your design on
one of my stm boards. Not sure how to get this back on time-nuts topics
Regards
Try a 6DJ8 instead of the 12AX7. It has a higher GM and a LOT more
bandwidth. What kind of risetime are we talking about for a lightning
strike? And why not a loop antenna? That should provide plenty of signal
but not destructive voltages.
I know you are talking about measuring lightning strikes but if you get the
impedance high enough, you can actually measure the earth's electric field.
(It is about 200V/m if I recall properly.) Interestingly it is affected by
the solar flux and solar wind.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
"The power of accurate observation is commonly called cynicism by those who
have not got it."
-George Bernard Shaw
Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
Huson, MT, 59846
mail: POBox 404
Frenchtown MT 59834-0404
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com
How fast does the maltese cross turn?
Regards.
Max. K 4 O DS.
Email: max@maxsmusicplace.com
Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com
To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe@yahoogroups.com
To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe@yahoogroups.com
To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe@yahoogroups.com
----- Original Message -----
From: "Neville Michie" namichie@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, June 25, 2014 10:46 PM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
Is anyone using a field mill?
I have always been going to make one.
It consists of a horizontal metal plane with a conducting button on the
surface
which is insulated from the ground plane.
A metallic maltese cross driven by a motor alternately covers and uncovers
the electrode
exposing/not exposing it to the sky.
The electrode button has capacitance to ground which drops its impedance,
but across that impedance is an AC voltage proportional to the ambient
static field.
A typical field in fine weather is 300 Volts/metre so the signal is not
trivial.
You should be able to make a field mill that works continuously except
when
actually shorted by rain.
This is not a very high impedance device, and should show many marvellous
things
as the clouds float over you.
You can calibrate it with a metal plate, say 12 inches above it with 50
volts on it.
That should produce a uniform field on the mill.
cheers,
Neville Michie
I know you are talking about measuring lightning strikes but if you get
the
impedance high enough, you can actually measure the earth's electric
field.
(It is about 200V/m if I recall properly.) Interestingly it is affected
by
the solar flux and solar wind.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi,
the maltese cross is a chopper to interrupt the lines of electrostatic force.
The cross could have a hundred legs, as long as it alternately blocks
and unblocks exposure to the electric field.
The cross spins in a horizontal plane, maybe half an inch above the sensor
electrode which is flush or just above the ground plane.
The idea is to get the output signal up to a frequency where the time constant
of the sensing electrode can be quite short.
If you can get it up to 400 Hz it only needs a 2.5mS time constant.
Even then, since you can calibrate it you can have the signal below the time constant.
A 12 legged "cross" spinning on a 4 pole motor gives a chopping frequency of 360 hertz,
(in America), quite convenient for amplification and processing.
If the motor is synchronous, or you put a sensor on the motor shaft you can run a phase
sensitive detector and get polarity as well as magnitude.
cheers,
Neville Michie
On 27/06/2014, at 1:59 AM, Max Robinson wrote:
How fast does the maltese cross turn?
Regards.
Max. K 4 O DS.
Email: max@maxsmusicplace.com
Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com
To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe@yahoogroups.com
To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe@yahoogroups.com
To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe@yahoogroups.com
----- Original Message ----- From: "Neville Michie" namichie@gmail.com
To: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Sent: Wednesday, June 25, 2014 10:46 PM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
Is anyone using a field mill?
I have always been going to make one.
It consists of a horizontal metal plane with a conducting button on the surface
which is insulated from the ground plane.
A metallic maltese cross driven by a motor alternately covers and uncovers the electrode
exposing/not exposing it to the sky.
The electrode button has capacitance to ground which drops its impedance,
but across that impedance is an AC voltage proportional to the ambient static field.
A typical field in fine weather is 300 Volts/metre so the signal is not trivial.
You should be able to make a field mill that works continuously except when
actually shorted by rain.
This is not a very high impedance device, and should show many marvellous things
as the clouds float over you.
You can calibrate it with a metal plate, say 12 inches above it with 50 volts on it.
That should produce a uniform field on the mill.
cheers,
Neville Michie
I know you are talking about measuring lightning strikes but if you get the
impedance high enough, you can actually measure the earth's electric field.
(It is about 200V/m if I recall properly.) Interestingly it is affected by
the solar flux and solar wind.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The tube was probably the FP-54
http://frank.pocnet.net/sheets/141/f/FP54.pdf
No luck on finding the article - it is not in the Handbook of Projects for
the Amateur Scientist by C.L. Stong
http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti
st.pdf
I thought it might be as I remember there was a project to detect sferics
but this one used plain 12AU7s and 6AU6s
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Poul-Henning Kamp
Sent: Wednesday, June 25, 2014 13:45
To: Discussion of precise time and frequency measurement; Didier Juges
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
In message
16957e54-f6d5-4c0a-9068-6f0c772d2082@email.android.com, Didier Jug
es writes:
I think it would be perfectly appropriate to design an LF amplifier
with 12AU7s considering the high signal levels when the storm does
get close.
Somewhere, sometime, I saw an homebrew article for a
lightning detector
which was based on some obscure valve/tube that had grid on the top
terminal.
A wire from the grid electrode ran to a porcelain isolator and from
there to the wire antenna, in order to get the highest possible
imput impedance.
I have no idea where I saw that article, but some HAM magazine or
possibly Elector about 10-20 years back is a good guess.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On Thu, Jun 26, 2014 at 9:08 PM, DaveH info@blackmountainforge.com wrote:
The tube was probably the FP-54
http://frank.pocnet.net/sheets/141/f/FP54.pdf
No luck on finding the article - it is not in the Handbook of Projects for
the Amateur Scientist by C.L. Stong
http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti
st.pdf
I thought it might be as I remember there was a project to detect sferics
but this one used plain 12AU7s and 6AU6s
When I was a kid this may have been my favorite book. I did build the MRS
when I was 12. Sucker actually worked too! I was amazed. I have built
several things from this and used many of the projects with modern
electronics as projects for my students in middle school.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
I have never seen an article using exotic special tubes. I understand that
benefit but common tubes do a fine job. I still believe it was a QST
article. Maybe 73 magazine. It was a long time ago. When I started using
the 12AU7s again for the vlf pre-amp they were $1 or so 7 years ago. Now
audiophiles have driven them into the silly range especially on the
websites. I scrounged 4 at really good prices $2 recently. But the
audiophiles were on the hunt as I noticed.
Bottom line a tube frontend is easy to build for this application. Even if
we want to make it seem hard. Its simply not the front end. Its the other
parts of the solution that should be the focus. How to make a sub $$
solution. The European solution is several hundred Euros. $$$$
Regards
Paul
WB8TSL
On Thu, Jun 26, 2014 at 10:50 PM, Brian Lloyd brian@lloyd.com wrote:
On Thu, Jun 26, 2014 at 9:08 PM, DaveH info@blackmountainforge.com
wrote:
The tube was probably the FP-54
http://frank.pocnet.net/sheets/141/f/FP54.pdf
No luck on finding the article - it is not in the Handbook of Projects
for
the Amateur Scientist by C.L. Stong
st.pdf
I thought it might be as I remember there was a project to detect sferics
but this one used plain 12AU7s and 6AU6s
When I was a kid this may have been my favorite book. I did build the MRS
when I was 12. Sucker actually worked too! I was amazed. I have built
several things from this and used many of the projects with modern
electronics as projects for my students in middle school.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Let's see - lightning is basically a powerful spark. How about a
home-made Marconi coherer?
You don't have to go back in time to get one, and the audiophools
haven't found a use for it.
Bill Hawkins
-----Original Message-----
From: paul swed
Sent: Friday, June 27, 2014 8:10 AM
How to make a sub $$ solution. The European solution is several hundred
Euros. $$$$ Regards Paul WB8TSL
I think the QST article being referred to in this thread is one that I
remember rather clearly. I kept the issue for a long time but it got away
from me somewhere along the line. It was a lightening direction finder
using a display much like a radar PPI. It used two crossed untuned loops
and a vertical. All three signals were amplified using tubes and one of the
loops was fed to the horizontal deflection plates of a CRT and the other
loop's signal was fed to the vertical plates. The signal from the vertical
was fed to the control grid of the CRT. The project was essentially an XY
scope built from the ground up. He suggested figuring out the polarity of
things by waiting for close lightening that was visible and correlating
sightings with the display on the CRT. You wouldn't use a general purpose
scope because the fair weather condition would burn a spot in the center of
the screen. One more thing. He wound the loops in hula hoops he had cut
open. I still have two hula hoops awaiting the project. The bandwidth of
his amplifiers was low audio to about 100 kHz. I suspect that in today's
radio environment some tuned traps would be necessary to notch out some of
the strong signals in that frequency range. You now have all the
information I have and I am sure I could build one if only I could find the
time.
Regards.
Max. K 4 O DS.
Email: max@maxsmusicplace.com
Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com
To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe@yahoogroups.com
To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe@yahoogroups.com
To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe@yahoogroups.com
----- Original Message -----
From: "paul swed" paulswedb@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Friday, June 27, 2014 8:10 AM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
I have never seen an article using exotic special tubes. I understand that
benefit but common tubes do a fine job. I still believe it was a QST
article. Maybe 73 magazine. It was a long time ago. When I started using
the 12AU7s again for the vlf pre-amp they were $1 or so 7 years ago. Now
audiophiles have driven them into the silly range especially on the
websites. I scrounged 4 at really good prices $2 recently. But the
audiophiles were on the hunt as I noticed.
Bottom line a tube frontend is easy to build for this application. Even if
we want to make it seem hard. Its simply not the front end. Its the other
parts of the solution that should be the focus. How to make a sub $$
solution. The European solution is several hundred Euros. $$$$
Regards
Paul
WB8TSL
On Thu, Jun 26, 2014 at 10:50 PM, Brian Lloyd brian@lloyd.com wrote:
On Thu, Jun 26, 2014 at 9:08 PM, DaveH info@blackmountainforge.com
wrote:
The tube was probably the FP-54
http://frank.pocnet.net/sheets/141/f/FP54.pdf
No luck on finding the article - it is not in the Handbook of Projects
for
the Amateur Scientist by C.L. Stong
st.pdf
I thought it might be as I remember there was a project to detect
sferics
but this one used plain 12AU7s and 6AU6s
When I was a kid this may have been my favorite book. I did build the MRS
when I was 12. Sucker actually worked too! I was amazed. I have built
several things from this and used many of the projects with modern
electronics as projects for my students in middle school.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
You might be thinking of the file that David Byrne sent to the HP list last year on 9/7/13. It was an article by C. L. Stong and I think it was published in The Amateur Scientist in 1963. You should be able to find it in the HP list archives.
Bob
From: Max Robinson max@maxsmusicplace.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Friday, June 27, 2014 11:14 AM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
I think the QST article being referred to in this thread is one that I
remember rather clearly. I kept the issue for a long time but it got away
from me somewhere along the line. It was a lightening direction finder
using a display much like a radar PPI. It used two crossed untuned loops
and a vertical. All three signals were amplified using tubes and one of the
loops was fed to the horizontal deflection plates of a CRT and the other
loop's signal was fed to the vertical plates. The signal from the vertical
was fed to the control grid of the CRT. The project was essentially an XY
scope built from the ground up. He suggested figuring out the polarity of
things by waiting for close lightening that was visible and correlating
sightings with the display on the CRT. You wouldn't use a general purpose
scope because the fair weather condition would burn a spot in the center of
the screen. One more thing. He wound the loops in hula hoops he had cut
open. I still have two hula hoops awaiting the project. The bandwidth of
his amplifiers was low audio to about 100 kHz. I suspect that in today's
radio environment some tuned traps would be necessary to notch out some of
the strong signals in that frequency range. You now have all the
information I have and I am sure I could build one if only I could find the
time.
Regards.
Max. K 4 O DS.
It was QST and Max is right. I built it. There was a e-field antenna for
amplitude and the crossed antennas the XY access. I guess the old brain has
somethings correct.
Now can I remember the tube line up. Heavens no. :-) The CRT was a little
mil surplus 3p...
But enough of that. Whats the chance of finding the article that would be a
kick.
Regards
Paul
WB8TSL
On Fri, Jun 27, 2014 at 12:28 PM, Bob Stewart bob@evoria.net wrote:
You might be thinking of the file that David Byrne sent to the HP list
last year on 9/7/13. It was an article by C. L. Stong and I think it was
published in The Amateur Scientist in 1963. You should be able to find it
in the HP list archives.
Bob
From: Max Robinson max@maxsmusicplace.com
To: Discussion of precise time and frequency measurement <
time-nuts@febo.com>
Sent: Friday, June 27, 2014 11:14 AM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
I think the QST article being referred to in this thread is one that I
remember rather clearly. I kept the issue for a long time but it got away
from me somewhere along the line. It was a lightening direction finder
using a display much like a radar PPI. It used two crossed untuned loops
and a vertical. All three signals were amplified using tubes and one of
the
loops was fed to the horizontal deflection plates of a CRT and the other
loop's signal was fed to the vertical plates. The signal from the vertical
was fed to the control grid of the CRT. The project was essentially an XY
scope built from the ground up. He suggested figuring out the polarity of
things by waiting for close lightening that was visible and correlating
sightings with the display on the CRT. You wouldn't use a general purpose
scope because the fair weather condition would burn a spot in the center of
the screen. One more thing. He wound the loops in hula hoops he had cut
open. I still have two hula hoops awaiting the project. The bandwidth of
his amplifiers was low audio to about 100 kHz. I suspect that in today's
radio environment some tuned traps would be necessary to notch out some of
the strong signals in that frequency range. You now have all the
information I have and I am sure I could build one if only I could find the
time.
Regards.
Max. K 4 O DS.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.