Transfer resistor = Transistor

My son Frank sent me a link to HOW DO THEY REALLY WORK? by William Beaty, BSEE 1995 and I am pleased to report that this is the best explanation I have ever read on transistor basic principles. For years and years I was baffled by all previous explanations and this article told me why. There are useful links at the end for more visualizations plus a nifty article on Iron Pyrites Negative Resistance Oscillator with a DIY cat whisker radio.