A heartbeat rate indicator comprises a detection electrode (1) for receiving an electrocardiac potential signal, an amplifier circuit (3) for amplifying the electrocardiac potential signal, a filter circuit (4) for removing noise from the amplified electrocardiac potential signal, an an amplitude detection circuit (5) for detecting pulses having an amplitude greater than a predetermined amplitude. An absolute value circuit (8) produces an absolute value signal from the output signal of the filter circuit, the absolute value signal being fed to the amplitude detection circuit.
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