Wednesday, October 27, 2010

Electric Cars

Hey guys,

Long weekend (fallout 3 came out, had an intense test in one of my classes, work, etc).

I've got a group project coming up. Our topic is on electric cars, and we need to write a huge paper, make a 30 min presentation (among other things).

Any electric car gurus out there want to point me to some sites full of info? I'd appreciate it!

Saturday, October 23, 2010

Matlab and Linear Discrete Signals

Hey guys,

Today I want to talk about a program I use in my Linear Signals and Systems course. It's called MATLAB, created by MathWorks. I use it for discrete signal plotting as well as tough math problems.

Taken from the MathWorks website, this shows some of the things MATLAB can do.

You can create some nice graphs with it as well as code up some interesting scenarios for systems. Make Differential Equations a little bit easier! Any of you guys use a similar program to MATLAB? I'd like to know some alternatives if they're out there.

Friday, October 22, 2010

Electronic Breadboards

Hey guys,

In lab I use these things all the time. They're a really cool way to make a circuit without soldering, and reusable over and over again. I found it neat how they're designed by watching this video:

Thursday, October 21, 2010

This day in Electrical History

On October 21, 1879 Thomas Edison created a light bulb that lasted 13.5 hours.

Without this invention, we'd still be lighting candles and lamps every night (and putting up with all that smoke). The only downside is now it's harder to see the stars in the sky from all the light cities put out!

Here's a picture of the earth at night taken by NASA. Check out those big cities! Shame about the places with no lights yet.

Wednesday, October 20, 2010

Midterm tomorrow

Huge test tomorrow for one of my Minor's classes (computer engineering minor, hate it. programming sucks).

Hopefully I'll survive the day, lol. Wish me some luck, brothers.

Tuesday, October 19, 2010

DC vs AC Power

DC power, or Direct Current power was the first power to fully electrify a city (Brockton, Massachusetts). Thomas Edison designed it that way, and invested heavily in DC power plant technology. He ran into some problems, however.

Edison wanted to keep the voltage low(100V), to keep people safe. The loss of voltage at these low levels due to the transmission wire's resistance was significant. (Vload=Vsource-IRwire) He sought out some solutions, but they had problems as well. He could reduce the wire resistance by increasing the wire's cross section, but that would really impact the cost of the wires. He could have a large amount of wires transmitting to high demand areas, but again, the cost would soar. In electricity distribution, money is what matters, and Edison was a businessman.

The solution to Edison's problems came from Nikola Tesla,a Croatian scientist Edison brought the the United States to help him. Tesla suggested using AC power, or Alternating Current power. He suggested this because of an invention known as a transformer only works in AC power, and it could jack up the voltage across the wires reducing lost voltage. Then when it got to the load, it could be stepped back down to safe levels by another transformer. It solved all the problems and was cheaper than DC's solutions to the voltage problem.

An example of an AC signal

Edison hated the idea of AC because he had so much invested in DC. He argued that the high voltage transmission lines were far too dangerous, and went to great lengths to get the public on his side (even publicly electrocuting animals, such as elephants). Eventually he was converted, and the AC we use today proliferated.

A lot of our devices we use today run off DC sources (a nintendo DS, for example, gets charged off DC. the plug has a AC/DC converter to change the outlet to DC and a lower voltage. I've even designed an AC/DC converter in a lab before, so it's not that complicated.

Monday, October 18, 2010

Electronic Configuration of Silicon

Ah, the good Ol' Periodic Table of the Elements. Thought finishing Chemistry class would be the end of this bad boy? No way. It's a useful tool for many, many professions.

The electronic configuration of an atom lists how many electrons are in each of its electron orbits. The outer shells are particularly important to an electrical engineer.

Let's look at Hydrogen, or H on the chart. It's electron configuration would be 1s^1, for having one electron in its outer shell (also it's only shell). Helium would then be 1s^2, filling up that first orbit. Those elements with full orbits are often called Noble Gases because they're highly stable (they don't crave any electrons because their outer shell is full, so they're less likely to bond with other elements spontaneously).

Moving on to Lithium, we have 1s^2 2s^1, meaning it's first orbit is full, and its second orbit has one electron. Other elements can be written in shorthand (because we often just care about the free electrons in the outer shell) using the noble gas preceding the element on the periodic table. This shorthand looks like this:
[He] 2sd^1

A nice chart labeling all the different letters for different orbits:

So, Silicon would be 1s^2 2s^2 2p^6 3s^2 3p^2
or simply [Ne] 3s^2 3p^2

These places have some great charts or lists for quick look-ups: