I say, keep it on the main channel. Too many different channels I fear would lead to dilution - those that like tutorials the most will subscribe only to that channel, those that like teardowns the most would only subscribe to that channel. I only have my one little channel that maybe 3 people subscribed to to watch my train videos, so I may have it all wrong about how YouTube works when you create multiple channels - if it doesn't matter and what actually counts is the aggregate of all people signing up for all your channels, then I suppose it wouldn't matter.
Perhaps after the whole additional host thing settles out and there's an EEVBlog Empire (just don't go all Palpatine) with a whole herd of hosts each producing content - then I can see multiple channels. Original EEVBlog channel with you only (and guests), and a channel for each of the various specialist topics that each host covers.
For white screen tutorials like this - where appropriate, maybe add some camera work showing a practical demonstration of the fundamentals being explained on the drawing pad. Nothing fancy, quick and dirty breadboard level experiment to demonstrate the topic. In the event that a demo circuit would be somewhat complex, it doesn't even have to be built on camera, you could have it prepared ahead of time and bring it into the shot. Shooting sequence wouldn't matter, then demo parts could be recorded before or after the lesson, and inserted in the final cut where needed. It's hard to judge since in this case you happened to pick a topic I know very well (but I watched anyway), but for something I'm less familiar with, seeing an operating example of the theory being presented definitely improves my comprehension.