This AC to DC converter circuit is capable of converting an alternative voltage within 70V – 260V range into a DC voltage within 180V to 350V DC range, so it can be used for 110V and 220V too. To ...

By manipulating the switching frequency and turns ratios of the transformer, the circuit can have an arbitrary output voltage. In this case, it is designed to take 220V AC and convert it to 8V DC.