Low-power circuits commonly use transformerless power supplies. However, the use of earth grounds in many of these circuits creates a serious problem that is often ignored. The very popular Microchip ...

This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn’t generate very much heat.The circuit draws about 30ma AC. Always use a fuse and ...

Many circuits can be powered directly from the mains with the aid of a series capacitor (C1). The disadvantage of this approach is that usually only one half cycle of the mains wave-form can be used ...