A T-junction circuit (12;13) for on-board power networks for an aircraft, the T-junction circuit (12; 13) comprising: a first connector; a second connector; a third connector; at least one data bus (18C,18D) communicatively coupled to the first, second, and third connector; a power bus (16C,16D) electrically coupled to the first, second, and third connector, the power bus (16C,16D) configured to receive unconditioned power at the first connector and to directly connect the first and second connectors to provide the unconditioned power directly from the first connector to the second connector; and power conditioning circuitry electrically coupled between a node of the power bus (16C,16D) and the third connector, the node of the power bus (16C,16D) located between the first, second, and third connectors, the power conditioning circuitry configured to condition the unconditioned power provided by the power bus (16C,16D) from the first connector to produce conditioned power that is provided to the third connector wherein the power conditioning circuitry comprises: surge protector circuitry configured to: prevent a voltage spike or a power spike from passing to the third connector; and prevent reverse current flow from the third connector to the first and second connectors; holdup capacitor circuitry configured to provide current in response to a power interruption or a voltage drop; direct current to direct current (DC-DC) converter circuitry configured to convert power from a first voltage to a second voltage; and linear regulator circuitry configured to maintain a voltage of the conditioned power. a first connector; a second connector; a third connector; at least one data bus (18C,18D) communicatively coupled to the first, second, and third connector; a power bus (16C,16D) electrically coupled to the first, second, and third connector, the power bus (16C,16D) configured to receive unconditioned power at the first connector and to directly connect the first and second connectors to provide the unconditioned power directly from the first connector to the second connector; and power conditioning circuitry electrically coupled between a node of the power bus (16C,16D) and the third connector, the node of the power bus (16C,16D) located between the first, second, and third connectors, the power conditioning circuitry configured to condition the unconditioned power provided by the power bus (16C,16D) from the first connector to produce conditioned power that is provided to the third connector wherein the power conditioning circuitry comprises: surge protector circuitry configured to: prevent a voltage spike or a power spike from passing to the third connector; and prevent reverse current flow from the third connector to the first and second connectors; holdup capacitor circuitry configured to provide current in response to a power interruption or a voltage drop; direct current to direct current (DC-DC) converter circuitry configured to convert power from a first voltage to a second voltage; and linear regulator circuitry configured to maintain a voltage of the conditioned power. surge protector circuitry configured to: prevent a voltage spike or a power spike from passing to the third connector; and prevent reverse current flow from the third connector to the first and second connectors; prevent a voltage spike or a power spike from passing to the third connector; and prevent reverse current flow from the third connector to the first and second connectors; holdup capacitor circuitry configured to provide current in response to a power interruption or a voltage drop; direct current to direct current (DC-DC) converter circuitry configured to convert power from a first voltage to a second voltage; and linear regulator circuitry configured to maintain a voltage of the conditioned power.