Over the years I've learnt a lot about TXs etc. But I'm a bit rusty. Any thoughts on general reminders about core saturation. I know there are huge issues, but the specifics I can't remember that well. I vaguely remember hearing something like when there is a DC component on a transformer the hysteresis curve would get shifted up. But what's the difference between say if you were using an air core or a saturated core in practice? (as far as V and I are concerened) So when the core saturates and the permeability drops away to near air permeability and the flux isn't increasing that much or hardly at all, what's the big deal? Still better than using an air core isn't it? Or are there spikes in current or something I'm forgetting that happen at saturation that are dangerous, that wouldn't happen if it was just a linear air core? Cheers Edit: actually one thought occurs to me, if the primary voltage is going up, but the dΦ/dt isn't going up much because it's saturated, then V2 = N2*dΦ/dt the voltage on the secondary will be kind of a square wave won't it? And I suppose there is little back EMF on the primary so it will draw heaps more current? But how does this contrast to if the TX was DESIGNED to be air core, instead?