The bypass unit 1012 includes a voltage monitoring unit 1012A, an LED indicator 1012B, and bypass circuit 1012C. The supply monitoring signal is generated by the voltage monitoring unit 1012A of the bypass unit 1012, and the LED indicator 1012B is located in the bypass unit 1012. The LED indicator 1012B sends a visual message to the user to indicate whether the input AC voltage is low with respect to the supply threshold. Likewise, in some implementations, the remote chime 1006 may be configured to ring differently based on the supply monitoring signal, thereby indicating whether the input AC voltage is sufficient to drive the doorbell camera 106. Arrangements shown in FIG. 10C may sometimes be utilized to simplify a process of setting up the doorbell camera 106. The bypass unit 1012 may be connected to the transformer 1010, the doorbell chime 1006 and a conventional doorbell 1024 i. e. , by connecting the wires 1014 1020. Then, the bypass unit 1012 generates the supply monitoring signal to indicate whether the input AC voltage is greater than the supply threshold, before the doorbell camera 106 needs to be connected to replace the conventional doorbell. Stated another way, if the supply monitoring signal indicates that the input AC voltage is not sufficient to drive the doorbell camera 106, a user does not need to take the efforts to replace the doorbell 1024 with the doorbell camera 106.