A measured signal amplifier (1) amplifies an EMG sensor signal (E). The measured signal amplifier (1) includes a sensor interface (2) for receiving the EMG sensor signal (E), at least one device interface (3) for receiving an electrical energy signal as well as for transmitting a processed signal (V), an electrically chargeable energy storage device (4) and at least one computer (5). The computer (5) is configured to derive a processed signal (V) from the EMG sensor signal (E) and to control the charging of the energy storage device (4) by the electrical energy signal as a function of the EMG sensor signal (E) received from the sensor interface (2).
