5 volt power supply directly from 120 volt
Something like this, used in home-power-line metering







simulate this circuit &ndash; Schematic created using CircuitLab

The 16v zener provides a clamped charging voltage for the 220uF capacitor. There will be substantial ripple on the 220uF. For 10mA I_Load, refreshed 1/50 seconds, given dV/dT = I/C, we have dV = (0.01amp / 0.00022Farad) * 0.05sec = 0.0005/0.00022 = 2volts ripple. So the linear regulator has some work to do, at 10mA load.