10 u2033 to case ground 12 on each of the brush leads 13 14 16 to eliminate noise generated by arcing caused by commutation of the brushes components such as inductor 20 and capacitor 22 form a low pass filter to reduce eliminate noise generated by a low speed brush 18 inductor 24 and capacitor 26 form a filter to reduce eliminate the noise generated by a high speed brush 28 while inductor 30 and capacitor 32 form a filter to reduce eliminate the noise generated by common brush 34 capacitor 38 represents the parasitic capacitance that exists between the motor case 40 and the armature 42 the ac sources 43 next to each brush 18 28 34 are intended to represent conceptually the noise generated by the brush arcing filters 10 10 u2032 10 u2033 work by shunting the noise as indicated by paths p 1 p 2 generated by brushes 18 28 and 34 back to the motor 39 as shown in fig2 prior art filters 10 10 u2032 and 10 u2033 are most effective if placed close to the source of the noise in this case the motor brushes 18 28 and 34 thus the loop area available to radiate electromagnetic interference is kept small for this.