Gaussmeter found dead

[John_H]

I potted mine with low temp hot glue, and then wrapped with shrink tube.

[salvarsan]

Plan B

Shrink tubing on all three leads works.
-drh

[Bruce Johnson]

I'm glad that you guys are doing the R & D! I'm so swamped that I haven't even opened up the bags on my kit yet. I'm sure that mine will be the last one to go together....

From reading this thread, I'll probably go with the heat shrink on the sensor leads, the heat shrink overwrap, and then encase the leads in an aluminum or brass sleeve.

[RedHouse]

I just clipped a heat sink on mine and used shrink tubing. I just waved the heat gun back and forth as not to over heat the sensor.

Then I put a larger sleeve over the three smaller ones.

I did the same on one probe, then did the epoxy thing on the other probe. Both ways work great.

I tend to stay away from a metal sleve, while I have no proof yet but my gut-feeling is that even a non-ferrous metal is having some effect on the magnet while measuring it.

[David Schwab]

I tend to stay away from a metal sleve, while I have no proof yet but my gut-feeling is that even a non-ferrous metal is having some effect on the magnet while measuring it.

That was my feeling too. I was going to put the probe in a plastic tube of some kind, but haven't done that yet.

[Dave Kerr]

I'm glad that you guys are doing the R & D! I'm so swamped that I haven't even opened up the bags on my kit yet. I'm sure that mine will be the last one to go together....

Ditto here - I wouldn't be so certain that you'll be last

[LtKojak]

Ditto here - I wouldn't be so certain that you'll be last

+ 3.

Maybe for Christmas...?

[defaced]

Yea, mine are still in bags. I won't hit them till after I sober up from being a workaholic in training and into my house. Christmas would be a good bet, if you're keen to losing.

[Bruce Johnson]

"That was my feeling too. I was going to put the probe in a plastic tube of some kind, but haven't done that yet."

Yeah, you're right. That's probably a better idea.

[David King]

Well I like to keep an eye on my probe, no covering at all for me. If it's stark naked it'll be less likely to misbehave. I might put some clear tubing over it if it gets a chill though.

[EtLa]

You can also use a shaped piece of forbon and 3 pickup eyelets to solder the allegro. That's what I did.

[Joe Gwinn]

I tend to stay away from a metal sleve, while I have no proof yet but my gut-feeling is that even a non-ferrous metal is having some effect on the magnet while measuring it.

Brass or aluminum or non-magnetic stainless steel will have no effect on static magnetic fields, which is what the gaussmeter measures.

The thickness of the metal over the sensor IC can slightly reduce the reading. If this is an issue, one can have the sleeve stop short, leaving the sensor exposed. Or, one can flatten and form one end of the tube into a narrow rectangular pipe that fits tightly around the sensor.

For electrical reasons, it's a good idea to connect the sleeve to the ground lead. This favors brass, which is very easy to solder to.

The reason to use a metal sleeve containing components embedded in a potting compound is mechanical ruggedness, plus a little added shielding. If the sensor is used only on guitar pickups in a benign environment, a shrink tubing sleeve should be sufficient.

[Joe Gwinn]

Shrink tubing on all three leads works.

In my sensor, the tubes on the sensor leads are solid teflon, and they worked perfectly. The problem was that the little knuckles formed when soldering the leads to another wire over time sank through the teflon-tape insulation between it and a knuckle in the adjacent lead.

Shrink tubing that can be slid into place after soldering and shrunk down over the center knuckle is one way to solve the problem.

[RedHouse]

Brass or aluminum or non-magnetic stainless steel will have no effect on static magnetic fields, which is what the gaussmeter measures...

I currently disagree. In my obeservations so far using the meter is appears even moving the probe around within the field seems to effect it somewhat even with bare leads and wire. When you get your meter back up-n-running, using it for a while and I bet you will also observe there is something going on besides the aluminum or non-magnetic stainless steel idea.

The following is totally unsupported but my thought is that the magnetic field position is not static when something (even non magnetic) passes through it, I'm thinking it displaces itself slightly depending on the density of the interfereing material, more for metal less for plastic.
(this might help explain why the magnet type can effect the sound, the type might effect the damping movement of the field area/position)

I've also noticed that moving the probe rapidly back and forth can give false high readings (up to a few hundred gauss) which might lend support to this notion of the field moving. Moving the probe slowly in toward the magnet then slowly across the pole gives the most repeatable readings.

I'm visualizing something like when one pokes the side of a water baloon with a finger, it doesn't change the total amount of water but it does displace the area it resides in, and with rapid probe movement I'm contemplating maybe it's like a tank of fuel in your car, you go around corners and the fuel gauge moves as the fuel sloshes around, which hasn't changed the total amount of fuel but gives inaccurate readings until the fuel settles down, likewise I'm thinking the magnetic field moves somewhat when something interferes/displaces the same space as it occupys.

Of course all this would only be an issue when profiling bar magnets since their charge is spread out along a greater polar edge, and it's much easier to get a consicse reading off the end of a rod magnet.

[Joe Gwinn]

I currently disagree. In my obeservations so far using the meter is appears even moving the probe around within the field seems to effect it somewhat even with bare leads and wire. When you get your meter back up-n-running, using it for a while and I bet you will also observe there is something going on besides the aluminum or non-magnetic stainless steel idea.

The following is totally unsupported but my thought is that the magnetic field position is not static when something (even non magnetic) passes through it, I'm thinking it displaces itself slightly depending on the density of the interfering material, more for metal less for plastic.
(this might help explain why the magnet type can effect the sound, the type might effect the damping movement of the field area/position)

For a static field, the sole effect of a non-magnetic metal is to cause a slight physical separation between magnet pole and sensor. Because in a pickup the field diverges rapidly with distance, any separation will reduce the measured field.

I've also noticed that moving the probe rapidly back and forth can give false high readings (up to a few hundred gauss) which might lend support to this notion of the field moving. Moving the probe slowly in toward the magnet then slowly across the pole gives the most repeatable readings.

I think I've seen that too. I believe that it is due to changing the sensor voltage too fast for the digitizer in the PIC to follow.

I'm visualizing something like when one pokes the side of a water balloon with a finger, it doesn't change the total amount of water but it does displace the area it resides in, and with rapid probe movement I'm contemplating maybe it's like a tank of fuel in your car, you go around corners and the fuel gauge moves as the fuel sloshes around, which hasn't changed the total amount of fuel but gives inaccurate readings until the fuel settles down, likewise I'm thinking the magnetic field moves somewhat when something interferes/displaces the same space as it occupies.

Something like this mental model works if one waves pieces of steel around, but nonferrous metals and plastics are simply invisible to magnetic fields, and you will get the same magnetic field shape and intensity as one would get if the pieces of nonferrous metals or plastics were replaced with air.

Of course all this would only be an issue when profiling bar magnets since their charge is spread out along a greater polar edge, and it's much easier to get a concise reading off the end of a rod magnet.

Actually, it's their flux that spreads out. The magnet does have a charge, and this charge drives a flux through nearby matter. If the matter is air, relatively little flux will flow. If the matter is solid iron, a lot of flux will flow. The flux ratio is a few thousand to one.

So, the analogy is that charge is like voltage, flux is like current, and the reluctance of the nearby matter is like resistance.