Fig. 2
Signals’ details. a Signal 7-21sFM: frequency modulated sine wave, between 7 and 21 Hz, complete sinusoidal sweep in 2.55 s. b Signal 14.1tAM: 14.1 Hz triangular symmetric wave, amplitude modulated by a 2 mHz (500 s period) 50% duty cycle (*) square wave. c Signal 7.8tAM: same as 14.1tAM, only that the carrier frequency was 7.8 Hz. (*) During the “low” intervals of the modulating square wave (for both, 7.8tAM and 14.1tAM), the signal injected to the coil did not went strictly to zero; instead, it went down to 1% of its peak value. For all three signals and all experiments, peak intensity of the AC current was 100 mApeak, and the DC current was of 450 mA