Digital Electronics Intro

 

Instead of using continuous signals, we are working on 2 states, in which things are either on or off. There's lots of 2-state systems based on voltages. The most popular you'll bump into is a 5-Volt System. A digital 0 is 0 volts, and a digital 1 is 5 volts, and these are just values and amplitudes. These are Digital only signals. We create an analog model to allow us to represent things as 1's and 0's. 5V, 0.5V, and 3.3V are very common.

At some point we need to get this analog information and bring it into the computer and something to process in. We get an analog signal, convert to digital signal, and then process it. Digital systems are never accurate since they are always and approximation on something that is occurring in an analog domain. 

For example, in mp3, we need a digital representation of a sound and we need to play the sound back. First we need to sample the sound, then we need to store the sound, and play this thing back and the playback will take digital information and convert it to analog, etc. The digital processing is at such a resolution such that the errors don't really make a significant difference. A power supply is analog, but will have digital components for control. 

SI system has Second, Meter, Kilogram, Newton, Coulomb (charge), Joule (energy), which Energy is in NM and current is Coulombs per second, Voltage is Joule per Coulomb, and power is joules per second. Newton is the force needed to accelerate a mass 1kg to 1 m/s^2. Coulumb is equal to 6.24 * 10^18 electrons. Voltage is like pressure, what "pushes the electron". It's the potential difference between 2 points in space.  One watt is one Joule per second which is just the amount of energy expended per second. 

10^-18 is atto, 10^-15 is femto, 10^-12 is pico, peta is 10^15, exa is 10^18.