Design and construction of a single-axis, low-frequency magnetic probe (B-dot probe) calibrated with a LCvar Helmholtz resonant circuit

M. Lindero Hernandez, A.G. Espino-Hernández, and M. Romero-Bastida


Magnetic probes (also known as B-dot coil) are electromagnetic devices used to measure magnetic
eld variations in many frequency ranges. The measured magnetic eld frequency directly relates to
the elected method to make the B-dot coil calibration. This work presents a B-dot coil calibration in
a frequency range from 6.16 kHz to 36.63 kHz. An inductor L (Helmholtz coil) connects in parallel
with a variable capacitor bank Cvar to form a coupled LCvar resonant circuit. The LCvar circuit is
fed with a half bridge oscillator. The capacitance Cvar is varied until the circuit is in resonant state
at dierent frequencies. The resonant circuit produces sinusoidal oscillations in the aforemention
frequency band. The sensitivity is calculated by using voltage Vout of the B-dot coil and voltage
VH measured from Helmholtz terminals.


B-dot, Half bridge oscillator, LCvar resonant circuit.

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Revista Mexicana de Física

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