Within a non-isolated and efficient AC-to-DC power supply circuit: 1) a dep-FET is turned off to decouple an output voltage VO node from a VR node when a rectifier output signal VR on the VR node is greater than a first predetermined voltage VP and, 2) the dep-FET is enabled to be turned on so that a constant charging current flows from the VR node and onto the VO node when VR is less than VP (provided that VO is less than a second predetermined voltage VO(MAX) and provided that VR is adequately greater than VO). To speed turn off and on of the dep-FET, gate charge of the dep-FET is removed and is stored in a second capacitor when the dep-FET is to be turned off, and charge from the second capacitor is moved back onto the gate of the dep-FET when the dep-FET is to be turned on.