I want to buy a voltage regulator, and I know that the market offers:
- Cheap-o types that are not real regulators, but instead switch between two coils to more or less approximate the desired output voltage, and also include simple filtering circuitry.
- There are also the "electronic" voltage regulators out there. That I must confess, have not bothered to check how they work (maybe they're the same thing as the coil-switchers)
- And then there are the true "ferro-resonant" regulators that weight like about a ton, and that I think are really some sort of isolation transformers with more sophisticated circuitry.