I found this and I'm a little confused.
It appears to be a simple component in to which I can put mains voltage and out of which get 3.3V DC without needing any other components - precisely what I want. Maybe I'm missing something, but from various googling this doesn't seem to be common, or used in circuits as a component of its own.
Could I, for example, use this single component to run an Arduino from mains? (there is a 12V version here)? Or to charge a mobile phone? Or, in my specific case, to connect a mains supply to a 3V relay 24/7 using minimal standby power.
Assuming I've understood what this component does, is there a better name for it? Googling "encapsulated electronic transformer" only returns this MYRRA product, but surely this is a generic thing... or is it?