Answering BJT questions with Karen on element14’s The Learning Circuit element14's The Learning Circuit 2019-01-02 Over on element14, Karen hosts The Learning Circuit. It is a tutorial show geared towards learning STEM basics. So far she has covered subjects like soldering, diodes, and how to make a DIY electromagnet. She did a great job on introducing BJTs and how they work. While I thought she provided a clear explanation of the internal workings, some members of the element14 community still had questions. She invited me on to revisit BJTs and transistors to (hopefully) clarify the connection between how transistors physically work and how to use them.