Archive for March, 2009

Our new kite

Monday, March 30th, 2009

This afternoon we took our new kite for a spin out at Lamar Park. Our kite is a 54″ delta, which is supposed to be easy to launch without a lot of wind. We got it up on our second try, which was better than I expected. We got it up 100 to 150′ before the Sun went behind the clouds and it started getting cold. It took several minutes to reel it back in. No pictures this time, but I’ll try to get some next time.

Luke enjoyed it, but I have no doubt I enjoyed it more than him. I haven’t flown a kite in years, and it was a lot of fun. In fact, a lot of this kid stuff is fun. I look forward to Luke building something besides towers with his Legos. Is he too young for model rockets? :)

I’m way behind with my “Luke and Liam Updates.” In the future I plan on making more shorter posts. When I try to do a big post every week or so, they just don’t happen. I’ll try to do a little catching up soon.

My homemade 2m 1/4 ground plane antenna

Tuesday, March 24th, 2009

As I mentioned a while back, last year I built a 2m 1/4 wave ground plane antenna to use with my handheld transceiver. I wanted a better antenna than the rubber ducky that came with my radio, and I also wanted to build an antenna. I think I posted about it on the old version of my blog, but the post didn’t get brought over.

2m 1/4 Wave Ground Plane Antenna

I used plans from here. The center part is a SO-239 connector I bought at Radio Shack, and the radiating element and radials are made out of uncoated brazing rods that I procured at a farm supply store. The vertical (radiating) element is 19.3 inches long, or a quarter wavelength electrically for the 2m band (144-148 MHz). The radials are slightly longer.

It works quite well. When I tune my radio to the local National Weather Service station I get a few S units of improvement over the rubber ducky antenna. Each S-unit is 6dB, so that’s quite an improvement. Using this antenna I can get into the local repeater when I didn’t have a prayer with the rubber ducky. Of course, now I use my Diamond antenna mounted on the house.

I intended to borrow an antenna analyzer from a local ham to see how close to 50 ohms I had managed to get. I never did, but I’ll be sure to do it when I borrow the analyzer for another project. Given the way it performs, it has to be relatively close.

A few more pictures here.

2m 1/4 Wave Ground Plane Antenna

Obama’s Ole Miss bag

Friday, March 20th, 2009

Time Magazine has a picture of President Obama’s personal bag being taken off of Air Force One at Andrews Air Force Base. It’s a really nice leather bag with the Ole Miss logo right there on the side of it.

At first I couldn’t think of why Obama might be sporting an Ole Miss bag, but then it occurred to me that the first debate was here, and it seems likely that Ole Miss would have given the candidates free stuff. It still seems odd that Obama would actually use the bag, but, then again, it is a nice bag.

“Our new house”

Friday, March 20th, 2009

As promised, I took some pictures Wednesday when I went to meet the home inspector. You can see them here. I’ve included a few here for those of you that don’t care to see all of them. As I was looking through the pictures I realized I didn’t get a good shot of the right side of the house, or a shot that shows the entire back yard.

Front

As you’ll notice, there are a few things that need to be fixed or tidied up before we move in. This includes refinishing the kitchen cabinets, fixing or replacing the cracked tiles in the kitchen, and painting the front door. Cassie wants to do some painting too. Also, as soon as I we close I want to go ahead and get some more trees in the ground. We’re running out of prime tree planting season.

As for the home inspection, I haven’t gotten the report from the home inspector, but last time I spoke to him (about two hours into the inspection) he said he hadn’t found any major issues.

It occurred to me while I was organizing the pictures that Cassie and I haven’t shared a bathroom in about six years, since we moved out of our first apartment. Of course, given the size of the master bathroom, that shouldn’t be a problem.

I’m sure I’ll be posting much more about the house.

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Buying a house

Thursday, March 12th, 2009

Cassie and I started house hunting last week, made an offer yesterday afternoon, and came to an agreement with the seller earlier this evening. We are quite excited about the prospect of being “homeowners.”

The house is in the South Oaks subdivision, which is about half a mile south of where we live now. It has three bedrooms, two bathrooms, and is a little over 1900 square feet. It sits on a 0.96 acre lot on a cul-de-sac, at the edge of the subdivision. The fenced-in backyard is huge, and the lot extends well into the wooded area behind the fence.

There are currently over 1,500 properties on the market in the Oxford area. However, due to our requirements and budget, our options were relatively limited. Firstly, we wanted the house to be in the Oxford School District. We want the kids to go to Oxford city schools (more on that later).

Secondly, we wanted a relatively large yard with some trees. When we began our search we defined “relatively large” as half an acre. We did much better with the yard that I could have ever expected.

On the other hand, we were hoping to get a four bedroom house, or at least three bedrooms and a bonus room. There were a few of those in our price range, but there was always something else “wrong” with them. Three bedrooms is a little on the tight side for us, but it’ll be fine. We plan on moving up in house in five or six years anyway.

The house was originally put on the market in August. The seller dropped the price 7.2% in October, and the price we agreed on was 5.3% below the reduced price. The price we agreed on was a lot less than we initially planned on spending. As our house hunt moved along we decided we’d prefer to spend less on a house and have a little more surplus income. I’m very happy with that decision, and I’m not sure I would have been so relaxed through the whole process if we hadn’t come to that conclusion early on.

Our contract states that we’ll close on or before April 15th, and we plan on being moved in by the end of April. There’s a lot to do between now and then. The first step is a home inspection. I’m sure you’ll be hearing much more about the house.

Flickr and Lightroom Upgrade

Tuesday, March 3rd, 2009

As you can see from my last post, I’m now using Flickr again instead of Zenfolio. I don’t have any real issues with Zenfolio, I just decided I liked the Flickr format a little better. I have deleted all of my existing Flickr photos and will be adding them back over time.

I also took the switch as an opportunity to upgrade from Adobe Lightroom 1.4 to 2. I don’t really need any of the new features, but the third-party Flickr plugin for 1.4 had some issues that were corrected in the LR2 version.

MintyBoost

Tuesday, March 3rd, 2009

As I mentioned, I got a soldering iron for Christmas (as requested), and the first kit I chose to put together was the MintyBoost Kit (v2.0) from Adafruit Industries. Make Magazine also sells it in their store. It’s a pretty popular kit, and if you haven’t heard of it before, well, you just don’t hang around in the right places. :)

The MintyBoost allows you to charge most USB-powered devices from two AA batteries. Actually, if you want to get creative you can connect anything that provides between two and five volts of DC. This guy uses two D batteries.

MintyBoost Components

The top of the MintyBoost circuit board with all components installed. To give you some idea of the sizes involved here, the PCB, from top to bottom, is about the size of a penny. Click on the image to go to its Flickr page. The Flickr image has notes describing the components and their purpose.

The primary purpose of this kit was for me to get some experience soldering. I’ve done a little soldering before, but very little, and never on a printed circuit board.

The heart of the MintyBoost is the LT1302 integrated circuit. There are a few capacitors to smooth out the input and output, a diode for reverse current protection, an inductor for the LT1302 to store energy to be converted, and some pull-up resistors to convince the USB device to charge. You can see the step-by-step building process here.

Apparently there’s no agreed upon standard for USB chargers. Most Apple products will charge if their two USB data lines are pulled high. The MintyBoost uses two 100k resistors for this. Other devices require other values of pull-up resistors or even pull-down resistors.

MintyBoost Soldering

The bottom of the MintyBoost circuit board after soldering.

The actual performance of the MintyBoost for charging my iPhone is a little disappointing. I get a little better than half a charge when using freshly charged Sanyo Eneloop AA batteries. At first I thought that the circuit could be improved by limiting the current through the MintyBoost with a single resistor. However, after I did the math correctly, that turned out to not be the case.

As it turns out, the iPhone just doesn’t charge very efficiently. USB (and thus the MintyBoost) provides 5V DC, but the iPhone battery is 3.3V. The iPhone undoubtedly uses a linear regulator in its charging circuit, which means it effectively turns into a heater when being charged. The extra voltage is just released as heat. Switching regulators are more efficient, but more complicated and expensive. Plus, when you’re charging from your computer or an outlet, it really doesn’t matter.

When I first saw the MintyBoost printed circuit board I thought both it and the pads on it were very small. Once I got started it was no problem though. It is easily doable as a first project.

I’ve got an Altoids gum tin ready for it to go in, but I need some more double-sided tape. I’ll post some more pictures once I get it in the tin.