S3E1: Node Equation Review

This is just a quick review of the node equation idea. In the following circuit there is one unknown node potential, labeled . The device parameters are: , , V, V.

What is the unknown potential (in Volts)? 6.21

e = ((e-V1) / R1) + ((e+V2) / R2)

[1/R1 + 1/R2] * e = (V1 / R1) - (V2 / R2)

[R2 / (R1*R2) + R1 / (R1*R2)] * e = (V1 / R1) - (V2 / R2)

[R2 / (R1*R2) + R1 / (R1*R2)] = (R2+R1) / (R1*R2) = 0.00032563

e = ((V1 / R1) / 0.00032563) - ((V2 / R2) / 0.00032563)

e = ((5.0 / 6800) / 0.00032563)  - ((-7.2 / 5600) / 0.00032563)

e = (0.000735294 / 0.00032563) - (-0.001285714 / 0.00032563)

e = 2.258065903 + 3.948389276 = 6.206455179

e = 6.21 Volts

VeloxMUD Mobile Authenticator

So I've been writing a MUD since Christmas Eve of 2011. Recently I took a two month break from the project to get some distance from the code, research some ideas in existing MUDs, etc.

This weekend I had a thought ... wouldn't it be neat if my MUD had a Mobile Authenticator similar to Blizzard's Battle.Net Mobile Authenticator?

So I wrote one: https://github.com/blinkdog/veloxmud-mobile-authenticator

The authentication code changes every 15 seconds...

Now I have to add the authentication routines to the MUD itself. I don't think that will be nearly as hard as futzing with the Android layout!

Android Virtual Device on 64-bit Linux

So I was trying to create a new Android Virtual Device (AVD) and it didn't work...

So I did a quick search and found an article on anddev.org:

All right, I was able to figure out the problem. The short of it is that I was using 64-bit Linux and had not installed the ia32-libs package, so the mksdcard utility was not working correctly. After installing this package, I was able to complete the step of making a virtual device.

So I took the advice and ran this:

sudo apt-get install ia32-libs

And then I was able to make my AVD.

Just a second...

So I wanted my desktop clock in GNOME 3 to display seconds. I did a quick search and found an article on AskUbuntu.com:

Yes, run this command in a Terminal: 

gsettings set org.gnome.shell.clock show-seconds true 

And you can verify with: 

gsettings get org.gnome.shell.clock show-seconds

And it worked like a charm. My desktop clock is now displaying seconds.

S2E6: Modeling

Joe has a barn that is feet from his house. He needs to supply 1000 Watts at 240V to a resistive load at his barn from the 60Hz power line at his house. Note that the circuit from the house to the barn requires two lengths of the interconnecting wire. He proposes to use number AWG wire to connect his house to his barn. Number AWG copper wire has a resistance of per 1000 feet.

What is the total resistance (in Ohms) of the transmission line?

(190.0 / 1000) * 1.588 = 0.30 Ohms

What is the resistance (in Ohms) of Joe's load at his barn?

V=IR

240 = I * R

P=IV

1000=I*240

(1000/240) = I

I = (1000/240) = 4.17

240 = (1000/240) * R

240 / (1000/240) = R

R = 240 / (1000/240) = 240 / 4.17 = 57.6 Ohms

What is the voltage drop (in Volts) from the house to the load at the barn due to the resistance in Joe's transmission line?

V=IR

V = (4.17)*(0.30) = 1.25 Volts

1.25 Volts * 2 lengths of wire = 2.5 Volts