Thanks, I admit that one controller is better…..(eg one error amplifier for multiple units etc etc)……though in some ways I like the idea of a totally independent unit, that doesn’t need its control linking up to other units…where the local ground may not be the same due to current flows, etc……and indeed, different units are likely to be on different PCBs and a single error amp signal would need wiring between units.....for two units maybe a single feedback signal is best, but for a great many units, we like the idea of multiple independent units, each self contained....ie as in the top post.