https://youtu.be/JO_EHceV9sk

It seems like this could be refined and used at events to test single pills.

It likely wouldn't work to detect fentanyl laced pills but it might still be useful to verify if it has the claimed compound.

Its related to NMR spectroscopy.  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

Fourier Transform Nuclear Magnetic Resonance Spectroscopy Experiment for Undergraduate and Graduate Students

Matthew A. Doscotch , John F. Evans and Eric J. Munson
Department of Chemistry, University of Minnesota, Minneapolis, MN 55455
J. Chem. Educ., 1998, 75 (, p 1008
DOI: 10.1021/ed075p1008
Publication Date (Web): August 1, 1998
http://pubs.acs.org/doi/pdf/10.1021/ed075p1008



US 2561489 Method and means for chemical analysis by nuclear inductions
nmr with trimmer paddle


US 2561489 (forward search)

US 2887673 Pulsed nuclear induction spin echo technique
split peaks fig. 6, o-scope

US 2960649 Line narrowing gyromagnetic apparatus
o-scope, spinning -> higher resolution, EtOH spectrum

zip file attached

LabView

Laboratory Interfacing Using the LabVIEW Software Package
Paul J. Ogren , Thomas P. Jones
J. Chem. Educ., 1996, 73 (12), p 1115
Publication Date (Web): December 1, 1996 (Article)
DOI: 10.1021/ed073p1115
http://pubs.acs.org/doi/pdf/10.1021/ed073p1115

Teaching Analytical Instrument Design with LabVIEW
Rudy Gostowski
J. Chem. Educ., 1996, 73 (12), p 1103
Publication Date (Web): December 1, 1996 (Article)
DOI: 10.1021/ed073p1103
http://pubs.acs.org/doi/pdf/10.1021/ed073p1103

Data Acquisition in the Chemistry Laboratory Using LabVIEW Software
Mark A. Muyskens , Samuel V. Glass , Thomas W. Wietsma and Terry M. Gray
J. Chem. Educ., 1996, 73 (12), p 1112
Publication Date (Web): December 1, 1996 (Article)
DOI: 10.1021/ed073p1112
http://pubs.acs.org/doi/pdf/10.1021/ed073p1112

A Low-Cost Dynamic Surface Tension Meter with a LabVIEW Interface and Its Usefulness in Understanding Foam Formation
Pietre Spanoghe , Jan Cocquyt and Paul Van der Meeren
J. Chem. Educ., 2001, 78 (3), p 338
Publication Date (Web): March 1, 2001 (Article)
DOI: 10.1021/ed078p338
http://pubs.acs.org/doi/pdf/10.1021/ed078p338

LIMSport: Optimizing a Windows-Based Computer Data Acquisition and Reduction System for the General Chemistry Laboratory
Ed Vitz , Brenda P. Egolf
J. Chem. Educ., 2002, 79 (9), p 1060
Publication Date (Web): September 1, 2002 (Article)
DOI: 10.1021/ed079p1060
http://pubs.acs.org/doi/pdf/10.1021/ed079p1060

Linux and the Chemist
Jerry F. Moore and Michael P. McCann
J. Chem. Educ., 2003, 80 (2), p 219
Publication Date (Web): February 1, 2003 (Article)
DOI: 10.1021/ed080p219
http://pubs.acs.org/doi/pdf/10.1021/ed080p219

How Students Use Scientific Instruments To Create Understanding: CCD Spectrophotometers
Eric G. Malina and Mary B. Nakhleh
J. Chem. Educ., 2003, 80 (6), p 691
Publication Date (Web): June 1, 2003 (Article)
DOI: 10.1021/ed080p691
http://pubs.acs.org/doi/pdf/10.1021/ed080p691

Constructing a High-Sensitivity, Computer-Interfaced, Differential Thermal Analysis Device for Teaching and Research
L. M. Martínez , M. Videa , F. Mederos and J. Mesquita
J. Chem. Educ., 2007, 84 (7), p 1222
Publication Date (Web): July 1, 2007 (Article)
DOI: 10.1021/ed084p1222
http://pubs.acs.org/doi/pdf/10.1021/ed084p1222

Assembly of a Modular Fluorimeter and Associated Software: Using LabVIEW in an Advanced Undergraduate Analytical Chemistry Laboratory
W. Russ Algar , Melissa Massey and Ulrich J. Krull
J. Chem. Educ., 2009, 86 (1), p 68
Publication Date (Web): January 1, 2009 (Article)
DOI: 10.1021/ed086p68
http://pubs.acs.org/doi/pdf/10.1021/ed086p68

Using Web-Based Resources To Incorporate LabVIEW into an Instrumental Analysis Course
Mark B. Jensen
J. Chem. Educ., 2009, 86 (4), p 525
Publication Date (Web): April 1, 2009 (Article)
DOI: 10.1021/ed086p525
http://pubs.acs.org/doi/pdf/10.1021/ed086p525

An NMR Experiment Based on Off-the-Shelf Digital Data-Acquisition Equipment
Christian Hilty and Sean Bowen
J. Chem. Educ., 2010, 87 (7), pp 747–749
Publication Date (Web): May 19, 2010 (Lab-Expt)
DOI: 10.1021/ed1002724
http://pubs.acs.org/doi/pdf/10.1021/ed1002724


Using communication software to capture experimental data
Estel D. Sprague and Thomas H. Ridgway
J. Chem. Educ., 1993, 70 (3), p A78
Publication Date: March 1993 (Article)
DOI: 10.1021/ed070pA78.2
http://pubs.acs.org/doi/pdf/10.1021/ed070pA78.2

Software to Interface the Student, the Lab Equipment, the Teacher, and the Computer
Ramon A. De La Cuetara and Ram S. Lamba
J. Chem. Educ., 1995, 72 (7), p 607
Publication Date: July 1995 (Article)
DOI: 10.1021/ed072p607
http://pubs.acs.org/doi/pdf/10.1021/ed072p607


software search in JCE

37. Using communication software to capture experimental data (BULLETIN).
Sprague, Estel D.; Ridgway, Thomas H. 1993, 70, A78

30. Software to Interface the Student, the Lab Equipment, the Teacher, and the Computer
De La Cuetara, Ramon A.; Lamba, Ram S. 1995, 72, 606

28. Laboratory Interfacing Using the LabVIEW Software Package
Ogren, Paul J.; Jones, Thomas P. 1996, 73, 1115

27. Data Acquisition in the Chemistry Laboratory Using LabVIEW Software
Muyskens, Mark A.; Glass, Samuel V.; Wietsma, Thomas W.; Gray, Terry M. 1996, 73, 1112

26. Integration of National Instruments' LabVIEW Software into the Chemistry Curriculum
Drew, Steven M. 1996, 73, 1107


labview

1. Teaching Physical Chemistry Experiments with a Computer Simulation by LabVIEW
Belletti, A.; Borromei, R.; Ingletto, G. 2006, 83, 1353

2. Integrating HPLC and Electrochemistry: A LabVIEW-Based Pulsed Amperometric Detection System
Jensen, Mark B. 2002, 79, 345

3. A Low-Cost Dynamic Surface Tension Meter with a LabVIEW Interface and Its Usefulness in Understanding Foam Formation
Spanoghe, Pietre; Cocquyt, Jan; Van der Meeren, Paul 2001, 78, 338

4. Teaching Analytical Instrument Design with LabVIEW
Gostowski, Rudy 1996, 73, 1103

5. Integration of National Instruments' LabVIEW Software into the Chemistry Curriculum
Drew, Steven M. 1996, 73, 1107

6. Data Acquisition in the Chemistry Laboratory Using LabVIEW Software
Muyskens, Mark A.; Glass, Samuel V.; Wietsma, Thomas W.; Gray, Terry M. 1996, 73, 1112

7. Laboratory Interfacing Using the LabVIEW Software Package
Ogren, Paul J.; Jones, Thomas P. 1996, 73, 1115

This is really neat. Unlike NMR, there's no fussing trying to get a uniform magnetic field (or being limited to the earth's field). Way easier to build in that sense.

Probably <$1k to build as is, without any further optimization, which is not bad for analytical stuff. And it would be a little annoying to use with all the tuning currently, but maybe you could design out some of the tuned elements with a fast enough TR switch.

What I'm wondering is how well it distinguishes relevant compounds. N and Cl are the common NQR-active elements, so say you are measuring the chemical environment of N atom. Looks like dimethylamine, diethylamine, and methamphetamine HCl easily distinguished (10.1016/j.ssnmr.2012.02.003). Methamphetamine vs. amphetamine should be easy, but methamphetamine vs MDMA is going to be a lot less of a difference.  If you are considering any analog with any kind of ring substitutions, I bet it gets tricky to correctly identify them. Imagine you are changing a methoxy to an ethoxy on a phenethylamine. That extension is two single bonds, two or three conjugated bonds, and then three more single bonds away from your probe nucleus. No experience with the technique, but it seems ambitious to detect that kind of small change and distinguish it from other similar small changes.

That being said, because this looks a lot more approachable than building an NMR instrument from scratch, I really hope my skepticism is misplaced. Need to find some better comparisons with spectra from closely-related compounds.