A respiratory apparatus comprising a power supply 4210 coupled to a bus 4422, and a blower configured to generate a flow of breathable gas. The blower includes a motor 4144 powered by the power supply via the bus 4422. The motor 4144 generates energy at certain times. There is a transient absorption diode circuit 4400 on the bus 4422 between the motor and the power supply to absorb the energy generated. A second invention is a fault mitigation circuit.