Consider a simple power supply / wall wart. Mains voltage in, 12V out. When you switch it off at the mains, while the load was drawing current, you'd get a massive voltage spike across the primary. So wouldn't you also get that voltage passed across to the secondary (with the relevant ratio), destroying the load? Or does the transformer not store enough joules to raise the voltage much through a load which is still connected?
2 months ago