What is Impedance, Anyway?
As you probably know if you’ve been shopping for cables, coax for most video applications is “75 ohm” coax–but what the heck does that mean, anyway? This article is a short, non-technical explanation of impedance, and its significance in video and other circuitry, for those who have always scratched their heads at this one. Every signal input, and every output, has an impedance–this “impedance” represents the relationship between voltage and current which a device is capable of accepting or delivering. But it’s hard to talk about electrons flying around in wire, and volts and amps, without making the whole subject seem abstract and obscure. Let’s think about another situation with which we’re all familiar: an automobile and its transmission. An automobile engine can put out a certain amount of power–horsepower, we call it. But the engine, itself, isn’t the only thing in the drive train. Between the engine and the road lies the transmission, and a transmission controls the relationsh
