But they don't use a lot of current. It's about 90V AC iirc to make it properly ring, and 20 Hz, you could do that with a switched capacitor network or, alternatively, by using a step up transformer (will be a bit heavier). Ugly solution would be to re-wind the coil so it works on a lower voltage and drive it directly.
Yeah, it's definitely doable on battery, it was just harder than not doing it/out of my league back then. I think I'll actually give it a shot on the next phone, as I think the PCB can easily fit now (it's only 5x5cm, as opposed to an Arduino Uno with shield on the first prototype).
I loved your LEGO sorter, by the way, it was very large-scale and a very interesting project, well done. I greatly enjoyed reading the writeup. Do you still use it?
Paid work has been absolutely insane the 2nd half of 2017, we are barely managing to recover before the next all-out job is landed so unfortunately no time to mess around with other stuff. I have a few more fun projects lined up, one of which has to be ready for next summer so I will definitely be making some time for play besides more work. Can't complain though.
Ah, lots of paid work is always good news. I'm looking forward to reading about your next project, it helps with my inspiration as well. Make sure you don't spend too much time working, fun is important.
> the ringer was too high-voltage to make work
But they don't use a lot of current. It's about 90V AC iirc to make it properly ring, and 20 Hz, you could do that with a switched capacitor network or, alternatively, by using a step up transformer (will be a bit heavier). Ugly solution would be to re-wind the coil so it works on a lower voltage and drive it directly.