On Sat, 23 Jan 2016 21:03:32 +0100, Dimitrij Klingbeil wrote:


Thanks for that, Dimitrij.
Well, I can scope it for a better view of what's happening, because
certainly the voltage readings don't make sense so your explanation rings
true with what I'm seeing here.
I have to say I've never probed one of these before. I'm familiar with
how they work at a block diagram level, but some of the actual circuit
topology is completely alien to me. It's a big obstacle.
So that's another thing to try tomorrow. I'll also recheck the B/E
junction of the chopper with the scope's filtering tweaked; see if I can
get rid of that noise....