Solar Power

I found an interesting table in a 2002 NREL report on solar power technologies (so it is in 2002 dollars), showing the price per kWh for various technologies:

So even in 2002, Parabolic Troughs and Power Towers were looking pretty promising! These technologies, when employing thermal storage, have now been developed (as of 2011) to a maturity level where they can achieve price-parity with conventional (fossil) fuels, at least in the Southwest United States.

Port Forwarding SSH with Actiontec M1000 DSL Modem

• First, make sure you have an SSH server installed and running, and listening on the normal SSH port (22).
• Make sure your server is on a static IP address, and that your DHCP settings on your router are such that the DHCP IP range excludes the static IP address you've entered for your server. (I've entered 192.168.0.4 for my server's local IP address)
• Now, make sure that the Actiontec's following two configuration screens look roughly like what you see below:

 

Tip: You probably won't be able to test out your SSH server's visibility on the Internet without physically going somewhere (like Starbucks), since it doesn't seem to allow doing a "u-turn" and connecting from your local network. If you have a server you can log into somewhere else, and then try logging in from there, that should work.

Current Regulator Circuit

Yippee! I successfully remembered my training as an electrical engineering student, and built a current regulating circuit to guarantee constant illumination from an LED under varying supply voltages.

(application: RC car headlights)

I won't bore you with a circuit schematic ;-) but it involves two LEDs each having a Vf of 2.0 V and an If of 20ma, a 75 ohm resistor, and a 10k resistor (though it probably oughta be 1k). The resistor values need to be adjusted for the Vbe of the 2n3904 transistor (~0.75 V under these conditions), but the goal is to guarantee 20ma through the LED on the top, for a Vs of 4 to 6V.

Quick Drying Random Things

Ever need something dried quickly, but can't microwave it, stick it in the oven, or put it in the clothes dryer? Try this!

Just tape a hair dryer into the opening of a PAPER grocery bag, put the thing to dry inside, and partially tape it shut. Turn on the hair dryer, and wait a couple of minutes. Whala!!

Zooming in GNU Octave under Ubuntu

Yay, I finally solved my problem! I can now zoom in Octave plots using the mouse (currently on Ubuntu 10.04 LTS).

I found the solution here

...but here it is so you don't have to scroll through all of that:

Build gnuplot with:
./configure --enable-volatile-data
make
sudo make install

and if necessary change the gnuplot's path in octave with:
gnuplot_binary ("/usr/local/bin/gnuplot") 

Just use the right mouse button to select the first point, then click a second time to select the other corner. Whala! Press "a" to go back to the original zoom level, and press "h" to dump some help out to the Octave terminal window.

Enjoy!

Pastebin Python Test

This is just a test of code-embedding from pastebin.com:



Did it work?

Mini Home Theater

Check out my sweet new mini home-entertainment system! I used to be into the whole "11-channel surround, 10,000W subwoofer" etc... thing, but in my old age, have decided most of that stuff is a gimmick. All you need are some decent speakers, well shielded cables, and a high-res (1080p) screen up close, so you can actually see the pixels. This system uses a PC (hidden under the end-table) hooked in through an HDMI input, running Ubuntu so I can surf the web. My keyboard is wireless, and has a built-in track-pad to minimize device juggling. The speakers are M-Audio powered monitors, which do a good job down to about 80 Hz... chosen to maximize audio quality while minimizing space consumption and neighbor-annoyance.