I can't quite get to the bottom of a USB peripheral auto-switching circuit diagram. [more inside]
posted by le morte de bea arthur on May 17, 2011 - 13 answers

How can I build my own A/B/A+B speaker selector box? [more inside]
posted by harkin banks on Jun 17, 2008 - 10 answers

Electronics for dummies? I need something very simple. There is one switch and two wires. When the switch is open, I want wire A to be grounded and wire B floating, when the switch is closed, Wire B should be grounded and wire A floating. Simple as that. What's the very very easiest way to achieve this (preferably using household equipment)? [more inside]
posted by grahamwell on Dec 26, 2006 - 6 answers

How do microchips work?

I understand it at a very basic level. I know that when you apply current to a semiconductor, it becomes conductive, and that this closes the gate in a transistor. By opening or closing the right gates, you're able to do basic counting and logical operations.

Here though, my conceptual model totally falls apart. Because try as I might, I can't get my head around exactly what it is that controls the current going to the semiconductor in the gate in the first place. How does the microprocessor know to open or close a particular gate? It seems like if it already knew to open or close a gate, then the operation has already been done. It's like you'd need another microprocessor controlling the current within the first microprocessor, and so an and so on back to some omniscient prime mover.
posted by willnot on Apr 12, 2004 - 13 answers