A power supply circuit for electronic equipment that might be affected by overheating or by a fire, the power supply circuit including a bistable switch switchable between a first state in which the input terminal is connected to the output terminal, and a second state in which the input terminal is not connected to the output terminal, a first coil, and a second coil, the bistable switch being configured to switch to the first state when the magnetic field induced by the second coil is greater than the magnetic field induced by the first coil, and to switch to the second state when the magnetic field induced by the first coil is greater than the magnetic field induced by the second coil.