You are right at the ringer machine at the tel. exchange. The bell is normally at the end of quite some line resistance. That would drop your current and smooth the waveform.
I do think a bell sounds better than a buzzer. I used a 555 calculator but I found I did need to tweak the values. The only problems with your mosfets driver is you will saturated the core with DC. You get better results if you connect the +DC supply to a centre tap and pull down each winding alternately. That’s how the mechanical vibrators work on the car valve radios. But your circuit looks to work very well.
Hi Chris, yes I love the the old bell sound, I've got the nearest I could find on my cell phone better than some stupid song like a lot of people have. Yes agree it would have been better with a centre tap and two mosfets in push pull I've used that method when building a switch mode psu but I was just using what came to hand & it's not really an important project, best wishes nick