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Re update on welding with an implanted defibrillator

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.

Reply to
Don Foreman
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BOM? Schematic? Please?

--Winston

Reply to
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.

Reply to
Don Foreman

"Don Foreman" wrote >

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

Steve

Reply to
SteveB

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.

Reply to
Don Foreman

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

Reply to
Karl Townsend

Hokay, Don.

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

Ya won't need it, though!

--Winston

Reply to
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 certa> I finished my magnetic field survey gizmo. I'm amazed at how well it

Reply to
Martin H. Eastburn

Good Luck with it! Gerry :-)} London, Canada

Reply to
Gerald Miller

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

Reply to
Gerald Miller

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

Reply to
Don Foreman

I think its Golden Valley for his job at Tennant, right near 100 and

  1. 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

Reply to
Karl Townsend

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

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

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

Reply to
Larry Jaques

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

Reply to
Don Foreman

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

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

Reply to
Larry Jaques

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