Design and construction of a nuclear magnetic resonator circuit

It is described the operation of a feedback circuit that it using the nuclear resonance phenomena and that covers a broad sweeping interval in frequency with a minimum adjustment of the circuit elements and it produces an appropriate nuclear absorption for a sign relation at reasonable noise. The circuit is an oscillator amplifier modulated that it is based its sensibility and stability in an inductive-capacitive arrangement in parallel and always operate in resonant condition, in such a way that the quality factor of Q arrangement has been very elevated. Thus when the nuclear absorption occurs it is producing a fall of Q effective. The oscillation amplitude is controllable and it maintains in a convenient value over the operation interval using control by feedback. The circuit uses a configuration 'Auto dyne Hop kin' that it suffers as a follower of inductive charge, which have the main characteristic of to cause a negative resistance that it appears through the tuning circuit. It is introduced a control for feedback via two trajectories, the first by differential pair for to maintain the amplitude level in RF and the second for to stability a band wide interval in the modulation condition. It is necessary since the RF signal value must have a value to excite the specimen nucleus without to carry to saturate it and that the permanence in the absorption region was appropriate. Between applications of the nuclear magnetic resonance phenomena we have the magnetic fields measurements, physicochemical molecular properties studies, training and medical instrumentation. (Author)