If you are looking for 5-volts DC regulator without transformer. This circuit may help you. It is suitable for low current digital. Use the MOSFET is based.
I collect these transformerless power supply circuit, use a capacitor instead, it smaller and lighter than transformer. There are circuits as follows.
This is Simple monitor turn on delay circuit, by use contact of relay acts as a switch. When entering an AC main to this circuit. The circuit will delay while Reduce the surge current protection with fuse.