If the load on the 12v output is precisely known, you can reduce the voltage from 230v to 12v by simply adding the appropriate sized capacitor in series with the line voltage. It is a form of transformerless power supply. But it has the following drawbacks:
1. It is very dangerous to touch any part of the circuit so powered, since you are touching 230v.
2. The output voltage will rise dramatically if the current draw is reduced. So you would have to ensure your load was constantly drawing exactly the same current all the time.