A transmission coil system has a first and a second transmission coil in which the first transmission coil is connectable to a stimulation unit, and the second transmission coil can be used as part of a resonant circuit which can be stimulated to resonate, and having a coil core for two transmission coils that are loosely magnetically coupled to one another in that the two transmission coils are wound alongside one another on the coil core. Stimulation of the first transmission coil leads to a resonant increase in the applied voltage in the second transmission coil, and thus to an amplified transmission power. This may be used, for example, for remote control of the hearing aid, since, for example, it allows 200 bits/s data transmission over several meters from a low-voltage source.