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Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Perhaps some magnet enthusiast is in a position to pick this up in person. It's a classic voltage integrator from the wooden box instrument era, like my Sensitive Research model FS. Note the adjustable feet for leveling the instrument. Ebay # 171013443317 --
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Ash Small wrote ...
All I've been able to find out about these 'Grassot fluxmeters' is that they are used to measure charge, Rich.
Am I looking in the wrong places? How would you use one to measure magnetic fields, which is what I assume you're implying it's used for.
I'll be up 'Barnsley way' in the next few weeks, I might put in a bid anyway, unless someone here really wants it.
See where the scale says "1 division = 10000 maxwell-turns = 100 microwebers"? It's configured to read the time integral of voltage (same as a flux change in a coil) instead of the time integral of current (same as a quantity of charge).
After putting a sense coil in the DC magnetic field under test, you use the instrument's up and down buttons to move the pointer to some round number. Then as you withdraw the sense coil and move it to a place of negligible B field, the pointer will move by an amount proportional to the coil's area and turns count, and to the initial B value, and practically independent of how much time the flux change took.
Want to measure the dipole moment of a permanent magnet? Put the magnet in the middle of a pair of Helmholtz coils, oriented parallel to the coil axis. Use fluxmeter to measure the flux change as the magnet is physically turned to point the other way.
I should make a video showing the response of my instrument of that type, next to the response of my active, electronic voltage integrating fluxmeter.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Well, I got it for £3.72. Assuming I can fix it, am I going to be able to use it to measure a flux of 0.0875T for electron cyclotron resonance @2.45GHz?
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Thanks Rich. I might bid on it.
The first one was further damaged in the post. Some screws were missing, and more damage occured inside. It's a bit of a mess, and I need to replace the screws and do a few other repairs (aralditing), but calibration is going to be the problem, so the second one may be useful, but I'm not going to bid a lot for it.
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classic fluxmeter (ballistic galvanometer) FS cheap in UK.
