Abstract: A wireless power adapter uses a passive conversion circuit to convert an incompatible transmitter-receiver pair into a compatible transmitter-receiver pair. The wireless power adapter transfers power between a main transmitter and main receiver that are incompatible with each other. In one aspect, the wireless power adapter includes an auxiliary receiver coil system, a auxiliary transmitter coil system and a passive conversion circuit. The auxiliary receiver coil system is compatible with the main transmitter and can efficiently receive wireless power transmitted by the main transmitter that is external to the adapter. The auxiliary transmitter coil system is compatible with the main receiver and can produce wireless power to be efficiently transmitted to the main receiver. The passive conversion circuit connects the incompatible main transmitter and main receiver by transferring power from the auxiliary receiver coil system to the auxiliary transmitter coil system.