I do vaguely recall that the first time I saw an OP-amp circuit it seemed insane. It's only after you learn about negative feedback, and forcing a virtual groun

I do vaguely recall that the first time I saw an OP-amp circuit it seemed insane. It's only after you learn about negative feedback, and forcing a virtual ground that you can work with the things and not think they're black magic. That was decades ago, I'd forgotten about it.