Wednesday, January 14, 2009


I just happened to notice that my blog was horribly updated, and my last post was from back in August. Last year I took a web programming class to motivate me to create a really decked out web page, but it only taught me that it's way too time consuming and too much effort. So here I am, using still.

I'm now on Skype, which seems like a really nifty online phone service. If you want, you can reach me with my user name, jfeucht82, and I'll try to leave it on as much as possible. My philosophy is that I should pay as little on telephone communication as humanly possible. If you've ever tried calling me, you've probably noticed that I rarely carry my phone on me wherever I go, and I respond to email a lot faster than I do via telephone. I currently own the cheapest AT&T pay-as-you-go phones I could possibly get, and it's malfunctioning because the ringer doesn't work anymore for some reason.

I was just looking through my online degree audit (or a listing of classes you still need to graduate), and I figured if I take the right classes, I might be able to graduate the end of Spring Quarter in June. I've been following mostly the program requirements of VLSI (Very Large Scale Integrated) Circuits, although the final courses I would need for that program aren't offered until the Summer or Fall quarter. On the other hand, I could take two engineering courses next quarter, and be done with the program requirements for Embedded Computing Systems, which is another field I have quite a bit of interest in. And I kind of want to exhaust the funds in my GI bill before I get out of the University of Washington, and I have funds to cover me through Fall Quarter this year, if I take classes over the summer.

So that's something I'm going to have to start thinking about. I've been prettying up my résumé and cover letter for possible internships and jobs coming up, and I have some career fairs to attend...

This quarter, I'm taking two engineering courses, and a writing course (I have to take two technical writing courses). I'm also taking my first 400-level UW course, E E 471 Computer Design and Organization. This class seems like it's going to be quite a bit of work. We're learning how to design our own microprocessor using Verilog, which is a computer language designed specifically for modeling digital circuits. Over the course of four lab assignments, we will design critical components of the processor. The class pretty much deals with figuring out how a processor processes machine code, and how all the components in a processor interact with each other.

The other engineering course I'm taking is E E 332 Devices and Circuits II, which is a continuation of an engineering class I took last quarter. This class deals primarily with designing circuits with BJTs (Bipolar Junction Transistors), which are pretty much electronic parts that amplify signals. Our final design project is to design and build an audio amplifier.

Anyway, that's all I have to say for now. Sometime in the near future, I might come up with something that's actually interesting to talk about and blog about it, but as for now, if you're too bored, you can check out my AC to DC in my previous post and marvel at how incredibly interesting it is.

An AC to DC Converter

In one of my classes, E E 331 Devices and Circuits I, our final project was to build an AC to DC converter. Our design specifications were to take a 10 Vpp 60 Hz DC input from a center-tap transformer and have an adjustable 10 V to 20 V DC output. It was expected to have output noise of maximum 100 mV, and able to deliver 1 mA current for all voltage settings. Also, we were graded on how cheap the circuit was to build.

Above is a block diagram of our design. The circuit works by rectifying an AC input, creating a high frequency square wave, and using that wave to drive a boost converter to amplify the rectified input signal to a level dictated by a differential amplifier you could control using a potentiometer.

And above is the circuit schematic as viewed in PSPICE schematic and simulation software. The circuit was designed mostly on computer, then built later when the simulated circuit met specifications. The square wave was provided by a 555 timer, and the differential amplifier was built using a LM741 operational amplifier. The amplifier compares the voltage at the anode of a 5 V zener diode with the output voltage, and increases its output voltage when the output voltage falls too low, and decreases its output when the output voltage gets too high. This feedback system maintains a constant output voltage, which is calibrated using a network of resisters to operate within the specified range.

Above is the circuit built on a breadboard. The total cost of all the electrical components is a little under $8. Our design had barely any noise in the output, and it met all performance requirements within a narrow error margin.