aliced25
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Anyone want to help design the circuit for Mini-NMR?
Ok, I am working on building a small mini-NMR magnet using a Halbach array with moving parts (some of the component magnets shift - ie. not just
shims). As has been demonstrated by the Author(s) of the attached paper, this allows for greater homogeneity and for "tweaking" the magnetic field.
That is all fine and dandy, but now comes the interesting part, the building of the electronic side of things.
Now for mine, we need a USB 2.0 port, which (a) provides a signal and (b) receives a signal. It also provides the power for the whole thing to work.
Now, a programmable oscillator is nice and cheap, so is a tunable rf transmitter (87.5-108MHz)/[url=http://www.sparkfun.com/commerce/product_info.php?products_id=8770]receiver (76-108MHz) pair. Or a signal generator which synthesizes sine waves from 1Hz to 25MHz.
There are also cheap as chips ADC/DAC's, Graphic Equalizer filters, amplifiers and all the rest.
Anyone want to help design a miniature circuit (all major signal processing would be done programatically)?
My idea is the USB delivers the signal to the Digital-to-Analog converter, the analog signal goes to the oscillator (programmed), then an amplifier to
the tuned rf transceiver (programmed & one part of the double-saddle coil is the output) and the signal is received by the rf-receiver (also
programmed & the other half of the coil) put through a filter, then converted from Analog-to-Digital and the digital data goes back up the USB
cord.
If that works (and the tunable rf arrangement should I think?), then it becomes a programming problem.
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aliced25
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Sorry, up-fucked that post, but anyway, finding the Larmor frequencies for such low-field magnetic flux is fucking hard work. The only paper I have
found so far is one from CERN, stating that if "Resonance absorption sample is a solid proton, then
the resonance frequency is 42.567 MHz/T." That being for fields between 0.14 and 1.7T. Here where we are dealing with a 0.5T field, the
resonant/Larmor frequency would be 42.567 MHz/0.5T = ~ 21.2835MHz.
IF that is the case then it poses MAJOR issues, that being right at the top of the AM Band (and I'd seriously dislike having to build AM circuits).
I'm presuming that a programmable oscillator could (16.8MHz-133MHz) could be used to send a square-wave pattern at that frequency (and for some
distance either side of it), without the need for all the fucking around with amplitude that comes with AM transceivers, but any ideas on how best to
receive it? Obviously it is not a "normal" AM transmission, it is just an FM-type transmission in the AM waveband, so the reception should be with a
modified FM receiver?
Shits me to tears actually, all that was needed was an intractable problem like the wavelength falling between readily available receiver IC's.
Could we receive the resonance + transmission and then modulate them? Thereby altering the received signal up so as to work with the off-the-shelf FM
receivers (ie. pump the piss out of the received stream with FM oscillation) and then remove the injected rf signal, leaving the resonance +
transmission to deal with?
Attachment: Muller.etal.Simple.Spin.Echo.Spectrometer.pdf (1.1MB)
This file has been downloaded 1137 times
Attachment: Klein.NMR.Free.Induction.Decay.and.Spin.Echoes.in.a.0.05.T.Magnetic.Field.pdf (403kB)
This file has been downloaded 1409 times
Attachment: Berkowitz.Pulsed.NMR.pdf (212kB)
This file has been downloaded 991 times
Attachment: Sahakian.Hayes.Yalvac.An.Inexpensive.Laboratory.Module.to.Teach.Principles.of.NMR.MRI.pdf (782kB)
This file has been downloaded 1436 times
Attachment: Wright.Brown.Spence.NMR.Hardware.and.Desktop.Systems.pdf (213kB)
This file has been downloaded 775 times
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Vogelzang
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Look at these patents.
NMR spectrometers
324/318 . Spectrometer components
319 .. Polarizing field magnet
320 ... With homogeneity control
321 .. Sample holder structure
322 .. Electronic circuit elements
324/322
US 2922947 Gyromagnetic resonance apparatus
US 2999977 Nuclear magnetic resonance measuring system
US 2999978 Nuclear magnetic resonance measuring apparatus
US 3005149 Nuclear magnetic resonance detectors
US 3034039 Device for ascertaining nuclear induction spectra
US 3042856 Nuclear magnetic resonance detectors
similar generator stage (triode 22)
US 3081428 Nuclear induction fluxmeter and magnet control apparatus
H2O, D2O column 4 line 45+
US 3153201 Oscillator-limiter-detector apparatus and method
US 3430128 METHOD AND MEANS FOR OBSERVING NUCLEAR MAGNETIC RESONANCES
with oscilloscope
US 3502963 SINGLE COIL NUCLEAR RESONANCE SPECTROMETER HAVING THE RADIO FREQUENCY EXCITATION
DIRECTIONALLY COUPLED INTO THE COIL
spectrum fig 3A, etc.
US 3795855 MAGNETIC RESONANCE PROBE SYSTEM
bridge
324/321
US 2960649 Line narrowing gyromagnetic apparatus
pneumatic sample rotation
US 3681683 GYROMAGNETIC RESONANCE SPECTROMETER UTILIZING AN IMPROVED SAMPLE SPINNING AND
EJECTING STRUCTURE
Varian
US 2908858 Decoupling means for electrical circuits
60 Hz, oscilloscope
--> 2,561,489 chemical analysis
US 3774102 AUTOMATIC NUCLEAR-MAGNETIC-RESONANCE POSITIONING APPARATUS
shows spectrum on chart recorder
US 6163154 Small scale NMR spectroscopic apparatus and method
US 6404197 Small scale NMR spectroscopic apparatus and method
US 3034040 Nuclear magnetic resonance spectrometer
details
US 3287629 Gyromagnetic resonance methods and apparatus
Varian, NMR
-------------
US 3085195 Gyromagnetic resonance methods and apparatus
NMR spec
US 3091732 Gyromagnetic resonance method and apparatus
air turbine
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