The output impedance of the generators is 50 ohms. Connecting a sub 1.5 ohm resistance coil to the output will provide 10 x (1.5 / 51.5) volts at low frequencies to the coil; less than 0.3 volts. The current flowing is 10 / 51.5; less than 0.2 amps. Total power = the product of the two, which is 0.057 watts.
You can clearly see from these simple calculations that the coils require a low-impedance driver to give any sort of power. Entrainment does not require high power levels, so it is OK for this, but for any real work, an amplifier is required.
Higher frequencies will deliver more power to the coil, as the inductive reactance rises, but this will not be detected using the needle of a compass. A nearby AM radio is better suited for this.
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