I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.

The prescribed "safe" level for 60Hz magnetic field is 1 gauss. The
sensor I selected has sensitivity of about 4 millivolts per gauss.
That's in the same ballpark as the levels from magnetic phono
cartridges and some dynamic microphones -- and we all know what
happens when a shield lead comes loose on those, right? BRAMMMM,as
the cones on the woofers come loose.

I selected a sensor that has differential outputs, figuring that'd
help deal with E-field hum.

Boy, did it! With the scope set at 200 mV/cm (half a gauss after x100
gain in the amp) I see about 50 mV of noise (expected) and there must
be some 60 Hz content in there but it sure doesn't stand out. This is
bare board on the bench, it isn't in a shielded box or even on a
ground plane. Dang, this dog is gonna hunt! Can it sense B-fields?
Ohhellyeah! It starts moving when I get within a foot of it with a
teensy little magnet (0.1" x 0.2" x 0.4") I took out of a Sonicare
toothbrush. Tomorrow I'll check it on 60 Hz with a soldering gun.
Then it's time to start taking data.

I have no reason to doubt that the sensitivity is per the spec sheet
but I can calibrate it later, even post implant. I need to get data
from welding situations while I can.

Tomorrow, figure out Fitch's scope-meter and start takin'some data
with MIG and TIG welding in progress. Hooaahhh!

If my data indicates that my welding setup and expectations would
carry more risk of a whack than I'm willing to accept, so be it. I'm
guardedly optimistic.

Don Foreman wrote:
I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.

BOM? Schematic? Please?

--Winston

On Thu, 15 Jan 2009 21:38:27 -0800, Winston
wrote:

Don Foreman wrote:
I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.

BOM? Schematic? Please?

--Winston

OK, yer on the post-implant ta-do list. Job 1 here is to grab some
data while I can.

Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

"Don Foreman" wrote
Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

So, you'll be welding first thing Saturday AM? ;-) Good luck. Those heart
procedures are fun if you get a cute nurse.

Steve

On Fri, 16 Jan 2009 05:48:12 -0700, "SteveB"
wrote:


"Don Foreman" wrote
Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

So, you'll be welding first thing Saturday AM? ;-)

No, but it may be a few days before I respond to Winston's request.
Whether or not I'll be doing any TIG or MIG post-implant will depend
on whether or not I can arrange things so magnetic field strength is
within specified safe limits. I gotta get my data now, pre-implant. I
don't have to reduce the data immediately, just record it and try to
minimize field strength by arranging cables, limiting current, etc. I
can calibrate the sensor and reduce data afterwards.

within specified safe limits. I gotta get my data now, pre-implant. I
don't have to reduce the data immediately, just record it and try to
minimize field strength by arranging cables, limiting current, etc. I
can calibrate the sensor and reduce data afterwards.

You're a bit pushed for time. And I can see this is an experiment that
should be replicated to verify uniform results. Why don't you plan on
"rent a Kid" post implant to verify your results?

Karl

Don Foreman wrote:
On Thu, 15 Jan 2009 21:38:27 -0800, Winston
wrote:

Don Foreman wrote:
I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.
BOM? Schematic? Please?

--Winston

OK, yer on the post-implant ta-do list. Job 1 here is to grab some
data while I can.

Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

Hokay, Don.

I got my fingers, toes and eyes crossed for you.

Ya won't need it, though!

--Winston

Soldering gun will drive it off the scale and then some.

100 amp + on the tip loop. Those babies are bad! Handy. Useful.

Magnetic field generator for certain!
[ that is how I used to magnetize bars. More turns or higher current.
Martin

Don Foreman wrote:
I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.

The prescribed "safe" level for 60Hz magnetic field is 1 gauss. The
sensor I selected has sensitivity of about 4 millivolts per gauss.
That's in the same ballpark as the levels from magnetic phono
cartridges and some dynamic microphones -- and we all know what
happens when a shield lead comes loose on those, right? BRAMMMM,as
the cones on the woofers come loose.

I selected a sensor that has differential outputs, figuring that'd
help deal with E-field hum.

Boy, did it! With the scope set at 200 mV/cm (half a gauss after x100
gain in the amp) I see about 50 mV of noise (expected) and there must
be some 60 Hz content in there but it sure doesn't stand out. This is
bare board on the bench, it isn't in a shielded box or even on a
ground plane. Dang, this dog is gonna hunt! Can it sense B-fields?
Ohhellyeah! It starts moving when I get within a foot of it with a
teensy little magnet (0.1" x 0.2" x 0.4") I took out of a Sonicare
toothbrush. Tomorrow I'll check it on 60 Hz with a soldering gun.
Then it's time to start taking data.

I have no reason to doubt that the sensitivity is per the spec sheet
but I can calibrate it later, even post implant. I need to get data
from welding situations while I can.

Tomorrow, figure out Fitch's scope-meter and start takin'some data
with MIG and TIG welding in progress. Hooaahhh!

If my data indicates that my welding setup and expectations would
carry more risk of a whack than I'm willing to accept, so be it. I'm
guardedly optimistic.

On Fri, 16 Jan 2009 00:39:21 -0600, Don Foreman
wrote:

On Thu, 15 Jan 2009 21:38:27 -0800, Winston
wrote:

Don Foreman wrote:
I finished my magnetic field survey gizmo. I'm amazed at how well it
works, he said modestly.

BOM? Schematic? Please?

--Winston

OK, yer on the post-implant ta-do list. Job 1 here is to grab some
data while I can.

Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.
Good Luck with it!
Gerry :-)}
London, Canada

On Fri, 16 Jan 2009 05:48:12 -0700, "SteveB"
wrote:


"Don Foreman" wrote
Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

So, you'll be welding first thing Saturday AM? ;-) Good luck. Those heart
procedures are fun if you get a cute nurse.

Steve

Don't know about heart procedures but, as a 19 year old, I had 12 (8,
then a week latter 4) upper teeth extracted in the dentist's chair.
His mid twenties assistant was very cute, very well built and very
knowledgeable in how to distract young male patients.
Gerry :-)}
London, Canada

On Fri, 16 Jan 2009 13:39:43 -0500, Karl Townsend
wrote:


within specified safe limits. I gotta get my data now, pre-implant. I
don't have to reduce the data immediately, just record it and try to
minimize field strength by arranging cables, limiting current, etc. I
can calibrate the sensor and reduce data afterwards.

You're a bit pushed for time. And I can see this is an experiment that
should be replicated to verify uniform results. Why don't you plan on
"rent a Kid" post implant to verify your results?

Karl

I might do that, Karl! Does he live or work near Fridley?

I might do that, Karl! Does he live or work near Fridley?

I think its Golden Valley for his job at Tennant, right near 100 and
55. He gets off most days in early afternoon. Let him come over for a
visit, something I should have done years ago already. But, I'm too
busy going after the elusive yellow tailed snapper!

I wish you well on Thursday. There's no such thing as minor surgery.

Karl

On Fri, 16 Jan 2009 23:02:13 -0500, the infamous Gerald Miller
scrawled the following:

On Fri, 16 Jan 2009 05:48:12 -0700, "SteveB"
wrote:


"Don Foreman" wrote
Feel free to ping if I forget. Implant day is next Thursday, I'll
probably be down for a day or so after that.

So, you'll be welding first thing Saturday AM? ;-) Good luck. Those heart
procedures are fun if you get a cute nurse.

Steve

Don't know about heart procedures but, as a 19 year old, I had 12 (8,
then a week latter 4) upper teeth extracted in the dentist's chair.
His mid twenties assistant was very cute, very well built and very
knowledgeable in how to distract young male patients.

I guess you'd bleed less while all your blood was busy filling up an
appendage, wouldn't you? wink, wink, nudge, nudge, knowwhatImean?

--
If we all did the things we are capable of doing,
we would literally astound ourselves.
-- Thomas A. Edison

On Sat, 17 Jan 2009 05:07:02 -0500, Karl Townsend
wrote:


I might do that, Karl! Does he live or work near Fridley?

I think its Golden Valley for his job at Tennant, right near 100 and
55. He gets off most days in early afternoon. Let him come over for a
visit, something I should have done years ago already. But, I'm too
busy going after the elusive yellow tailed snapper!

I wish you well on Thursday. There's no such thing as minor surgery.

Karl

Ah, I know where Tennant is. That's only 15 or 20 minutes from here
except possibly during rush hour.

On Sat, 17 Jan 2009 11:49:18 -0600, the infamous Don Foreman
scrawled the following:

On Sat, 17 Jan 2009 05:07:02 -0500, Karl Townsend
wrote:


I might do that, Karl! Does he live or work near Fridley?

I think its Golden Valley for his job at Tennant, right near 100 and
55. He gets off most days in early afternoon. Let him come over for a
visit, something I should have done years ago already. But, I'm too
busy going after the elusive yellow tailed snapper!

I wish you well on Thursday. There's no such thing as minor surgery.

Karl

Ah, I know where Tennant is. That's only 15 or 20 minutes from here
except possibly during rush hour.

So you'll be jogging there and back? Very good.

Break a leg, kid.

--
If we all did the things we are capable of doing,
we would literally astound ourselves.
-- Thomas A. Edison