ChetOS.net

My latest Arduino project is a device that logs into my bank and displays my checking account balance on an analog gauge (like a gas gauge on a car).

Using the WiFi capabilities of the YellowJacket from Async labs, every five minutes it connects a web service running on my web server.  My web service uses screenscraping to log into my bank account and determine the amount.  It converts this value to a range from 0-255 which is sent back to the Arduino.

The Arduino outputs this value on an analog pin which is connected to the gauge.  If my account has $500, it is "full".  If it is $0, it is "empty.

The YellowJacket was $55.  I got the gauge from Skycraft for around $10.  I also bought a nice enclosure box to put everything in, which was $5.  So, all told, the project cost $70.  That being said, the YellowJacket can be used for other projects (like my TwitterSwitch), so it isn't like I spent $70 just on this.

At Christmas time, my wife is always asking me to turn on the lights on the tree.  This means I have to get up, walk over there, reach behind the tree, and plug them in.  Then I have to do the same thing before we go to bed.

Now this will be a thing of the past.

The YellowJacket is an Arduino + WiFi device which I got for Christmas last year.  This allows the Arduino to connect to the internet.

I wrote a web service which checks the latest status of a particular Twitter user.  It then returns a 1 or 0 depending on the status.  "Turn on" is 1, "Turn off" is 0.

The Arduino checks the value of this web service every 30 seconds.  When the value is 1, it turns on a solid state relay.  I have this relay wired like a switch to a power outlet.  I just plug the lights into this power outlet.  The relay is rated up to 25 amps, so technically I could use this to control almost anything no matter what size.

The YellowJacket was a Christmas gift, but it costs around $55.  I got the solid state relay from Skycraft for around $5.  I also bought an A/C outlet from the Home Depot for a few dollars.  I just need to put it all in a box.

Now, when my wife wants to turn on/off the lights, she can just log into Twitter and post the correct command.

In addition, I have my phone set to post to this Twitter account, so I can just send a text and control the lights.  I am very proud of this project.

I build this project several months ago, but I forgot to post and entry on my blog.

I was perusing a book at Barnes and Noble over the weekend.  The book was about software development as an occupation (as opposed to the technical aspects).  Once chapter was about interviewing and some of the non-technical questions that people get from organizations like Google.

These are questions that you are not expected to know the answer to, but are intended to show your thought process.

There was only one question that I really looked at, it was "How many gas stations are in the United States?".  The example for how to come to an answer analyzed the question from the aspects of average number of cars served per hour.  He came up with 33,000.  He also said that to be considered correct, you should be within an order of magnitude (so his answer is close enough if the actual answer was closer to 33,000 than it it was to 330,000).

I gave it some thought the other day while I was driving, and I went about it in a different fashion.

Saint Cloud has a population right around 30,000.  After some thought, I determined that there were 12 gas stations in that city.  So, if I take this as an average city I would say that there is one gas station per 2500 people.  There are 300 million people in the United States, so this yields around 120,000 gas stations.  That would have been my answer.

So, I just thought to check my number.  Turns out, this is suprisingly close.  According to the 2007 census (latest data available), there are exactly 118,756.  I would say that I nailed that. :-)

I just heard John McCain say the dumbest thing about the Reid proposal to raise the debt ceiling.  He said the likes it because it cuts spending by more than it raises the debt limit.

Let's break this down:

It raises the debt ceiling by 2 trillion dollars, enough for it to last until the end of 2012 (just after the elections).  This is a year and a half, which means it raises it by about 1 trillion per year.

It cuts spending by 1 trillion dollars initially, over 10 years.  That means it cuts about 100 billion per year.  It has the ability to cut it by another 1.5 trillion if a committee can agree to the cuts.  This is not going to happen, but let's just say that it does.  That is another 150 billion per year.

So, he says it cuts spending my more than it raises the limit.  Not true, it raises the limit by 1 trillion per year and only cuts an absolute maximum of 250 billion per year.

And it 2012 they are going to have to raise the ceiling again, which diminishes the cut-to-limit ratio even more.