Magnetoresistive rotating-speed sensor for locomotive

The utility model provides a magnetoresistive rotating-speed sensor for a locomotive, which comprises a permanent magnet, a detection coil, an iron core, a detection circuit and a transmission cable, wherein the detection circuit comprises an automatic gain control processing circuit, and a low-pass filter circuit for filtering and removing a high-frequency interference signal in induction signals acquired by the detection coil. The magnetoresistive rotating-speed sensor can process the acquired signals, and further conducts self-regulation gain on the basis that the high-frequency interference signal in the induction signals acquired by the detection coil is filtered and removed preliminarily, so that the amplitude of an output signal is kept constant by the action of the gain. The magnetoresistive rotating-speed sensor can solve the problem that the signal output amplitude of the sensor is decreased due to demagnetization caused by vibration and temperature after the sensor is used for a long time, or that