Saturday, November 05, 2016

Christmas Lights - SMT Soldering

Last night was a night of working on small things: my wife continued her efforts on a counted cross-stitch stocking for me and I soldered some very small transistors to break-out boards.

Specifically, I soldered two IRLML2502s to a 10-pin SOT23 break-out board. I knew these transistors were small and I had figured out a way to squeeze two of them onto the break-out boards. It took me about an hour to make five the modules (one of which you see below) and I haven't electrically verified that all the connections are made properly so there may be a little bit of rework.


So, yeah, small. The horizontal dimension of one of the transistors is between 2.67 and 3.05 mm, the vertical, counting the leads, is between 2.1 and 2.5 mm.

My original plan was to solder these directly to 0.1" perf board that makes up most of the custom Arduino shield I'm making. I think that would still work with a little bit of fudging but when I realized I could get two transistors on one break-out board, I decided the extra hassle was worth having the transistors easily replaceable.

Because, oddly, there is no nominal current rating for these transistors, only an absolute maximum rating (4.2A continuous at 25'C, 3.4A at 70'C). I won't be needing more than 1A per channel so I feel safe using them but it feels a little bit like dangerous or rebellious engineering to use them not knowing what a normal current rating is. How lucky do you feel? How hot will they get? Will it work or will it end in the magic smoke being released? Having them on a module means I can easily replace a pair if something goes wrong.

You might notice that the second pin in from the upper right is missing. This is intentional and a result of my experiences on other projects. One of the most common problems I face with symmetrical connections is trying to figure out which way I should plug things in. Plugging in the wrong way can blow things up but I rarely want to take the time to go back to a schematic to figureit out. By leaving the pin empty I can put a dab of hot glue over the corresponding hole in the connector and effectively prevent myself from being able to plug these in backwards.

Oh, and in case you missed the title, I'm working on some decorative LED Christmas lights using the ever popular RGB LED strips. More to come, hopefully very soon.

Monday, October 24, 2016

Backyard Landscaping - Raised Garden Bed

My wife is committing to growing fruits, vegetables, and herbs.

At least that's how I see it after completing a sixteen by four by two foot raised garden bed. The project included borrowing a chop-saw from a friend, a slightly treacherous and probably ill-advised trip home from the hardware store with sixteen-foot pieces of lumber strapped to the roof of the car, and much more painting than I would have anticipated.

Oh, and digging in the dirt. Lots of digging.


So here is the box, assembled and upside down. The black boarder around the bottom is my attempt at keeping the Bermuda grass from growing up through the bottom of the box, just like I did with the basketball court removal. As before, we'll see if it does any good.


After a bit of digging, the grass was out and I began the process of digging out the holes for the feet. What I hadn't discovered yet is that there is a sprinkler pipe up near the foot of the stairs that is going to cause a bit of trouble. I had to shift the bed away from the patio concrete enough to clear that pipe.


With my wife's help, we managed to flip it over easily enough. And then I began the level process, digging around the footings, measuring, propping up and pressing down until it was more or less level. You can see a little dab of the white PVC pipe that made this just a bit more tricky.


The last step was moving all the dirt from the patio to the bed and kind of leveling it out. As you can see, the bed is only about a third full so before we plant in the spring we are going to need to get some more.

Saturday, September 17, 2016

Backyard Landscaping - Grass Almost There


Looking pretty good, eh?  Looking at the last photo from about six weeks ago, its starting to look like a real lawn; I even mowed for the first time this morning. Even without zooming in, you can see some bare spots and I re-seeded two weeks ago to try to fill those in. When I look closely, I can seem some of those seeds have sprouted but not near as many as I had hoped. I'll probably have to seed and fertilize again in the spring. At least we won't have a mud pit for the summer.

And there's more to my life than this lawn, I promise. Hopefully some of that will show up here soon.

Tuesday, August 23, 2016

Backyard Landscaping - Growing Grass Still


I don't know what to say other than this blog, as of late, is literally as exciting as watching grass grow.

And it will continue to be that way as it is clear from the photo above that I will need to add some seed in the coming weeks. The grass I planted doesn't grow super well in the heat and its just now cooling off from the summer. I'm hoping the second seeding will fill things in well enough that we can avoid mud for the winter.

Wednesday, August 03, 2016

Backyard Landscaping - Growing Grass

I know, I know. So many of you have been asking, "Whatever happened to that grass you planted?"
Here's a not-very-good picture taken after the sun had gone down this evening of this little guys getting going. I have no idea why they are popping up in such a patchy manner; I might have to re-seed in the fall before the water is turned off.


Sunday, July 24, 2016

Backyard Landscaping - Dirt In and Grass Planted

While I was out of town this past week, my sister and her husband came to help visit and assist my wife with all the running of the house and caring for our son. And while they were at it, they moved the rest of the dirt in. Last night I planted the grass and tonight, when our irrigation water returned, I started watering. Let's hope our recently spotty irrigation water holds up for a week or two so the seed can germinate.



The lighter spot in the lower left is not covered by the sprinkler head very well. Though they claim to spread the water uniformly, that is clearly not the case.  I'll be able to cover it decently with water from another zone.

Sunday, July 17, 2016

Backyard Landscaping - Smoothing the Fill Dirt

The dirt is definitely smoother but this photo is deceiving. There's still much more to move in and a lot of smoothing still to go.


Newberry National Volcanic Monument

So, before we begin with the pictures, the difference between a National Park and a National Monument in the United States has only to do with how they are created and who ends up responsible. National Parks must be created by Congress, National Monuments can be created by the President or Congress. (And I guess if there was ever a lawsuit about the status of such a site the Supreme Court would get in on the action? I wouldn't want them to be left out.) The Park Service runs the National Parks and some other agency ends up running the National Monuments.

Why do I bring this up? Because this past week I visited Newberry National Volcanic Monument, managed by the US Forest Service and I saw no difference between it and a National Park (except maybe for the fishing in the lakes). I feel like this is an indicator of the disfunction and cost of politics, that we need two mechanisms to essentially do the same thing because sometimes, one of them isn't working. I as an engineer I should appreciate the redundancy but it seems like redundancy in governance commonly goes by the name "waste". At least they all figured out having a common location to reserve campsites is a good idea.

OK, let's not dwell on such things any longer.

Last week we went camping! It was mostly wonderful aside from being very cold at night. Our one year old end up sleeping with us and with a cap on his head, he slept through the night like a champ. Being an outdoor boy, he loved having ready access to sticks, dirt and rocks.



My big event for the trip was a hike to a local peak. It was the most ambitious hike since injuring my foot with a 1400 foot increase in elevation and a total length of around seven miles round trip. I was hauling my son in a baby-carrier backback most of the way and I paid for a bit the next day but it was worth it. A view from along the way, showing the two lakes in the Newberry volcano caldera:



When we got to the top we found that there is a road that allows mere mortals to drive directly to the peak. The next morning, when our son woke early with the sun, being a mere mortal at that hour of the day, I drove up with him to get some sunrise pictures. The mountains you see are Mt. Bachelor and the Three Sisters.



The only other hiking we did was a short mile or so to the Pauline Falls; here's the view from the lower observation platform.