2004-08-16

Weekend Projects


This weekend I worked on a few different projects. Saturday and Sunday morning I worked some more on prototyping a circuit with a bunch of LED displays. I am using the same CPU as I have on my Tuna-can wheeled Robot. I've gone through a lot of different designs. The last time I worked on it, I realized that I might be overloading the circuits to drive so many LEDs. So I had researched using transistors. I had a bunch of small transistors in a grab bag, so I had started wiring up the circuit using 8 of them. But during initial testing, I saw that hooking up more than 2 LEDs caused a significant browning out on the light coming out of the LEDs. So I decided to check how a circuit on a microcontroller board I had drove 4 of 5x7 LED displays. They drove directly from the latch chips, without any transistors. So I went back to my prototype circuit, and wired it up directly to the chips without the transistors. On the second morning, I got the whole circuit put together. I had a little trouble getting my PC to program the chip, but it turned out to be a couple of my own errors in wiring the CPU (MCU). I managed to get the circuit to program with a little bit of debugging, just testing how it looked to run different segments on the LED displays, and the loose LEDs. Well, when I was just driving one to three LEDs at a slow refresh, it looked pretty good. But as soon as I got the rate up to run all the displays or even more than 3 of the displays, the LEDs just faded way out. I even took a chance overdriving the LEDs by bypassing the resistors. It helped a tiny bit, but it sure shows the problems with the circuit the way I have it laid out. The only thing I can think of right now, is that I'm running off a 9v battery through a 7805 voltage regulator. Perhaps the 9v battery or voltage regulator cannot handle it. I will have to look at changing those before I decide to go a different way with the circuit. I may have to find heftier transistors to get the circuit to work the way I want. Once again, my lack of EE (Electrical Engineering) background is showing. But sometimes, this is the only way to learn.

I also got around to mowing the front lawn this weekend. It is a pretty small patch, so it didn't take very long. Even with watering the lawn twice a week, and all the rain we have had, this is only the second time I've mowed the lawn this summer. The heat, sun and overall dryness just keeps the grass from growing very quickly. The only place the grass grows relatively quickly is where it is in shadow under the kids playstructure - where I cannot get the mower for the most part!

I took some time to use liquid weed killer to hit all the weeds growing around the house. I had done this once before about a month ago, but a few weeds didn't die off, and a whole bunch more have grown in. The worst spot is the uphill side of the driveway, where we have a bunch of rock over weed prevention cloth. Well we have a huge amount of grass moving in there. I think a lot of that is a side affect of all the rain. Amazing how grass grows so well where you don't want it, but gets all spotty where you do want it. I decided to hit the weeds that were growing in the street too, where the concrete and asphalt join about 6 inches out from the curb. I thought I had more lawn fertilizer with weed killer left, but I couldn't find it. The weeds are starting to move into the front yard. Especially along the sidewalk. So I will have to pick up a small bag soon. Heck, it is the right time: it may only be mid-august, but it already is feeling like fall. We are getting a bunch of cool days, and the kids are back in school.

This weekend, I also got around to a little plumbing work. The pipe that comes out of our house to feed the lawn sprinklers has had a long time problem with a pinhole leak. The leak originally happened a few weeks after the sprinkler was installed. We had called the installer about it, and he fixed it, and it managed to hold until the next year. But eventually it returned. It has even caused a little staining around the pipe. I had turned off the water, so there would not be an active leak when our house was inspected. I had purchase a propane plumbers kit a while back, meaning to get around to fixing the pipe. While, the time was ripe: the water was already off, and it was a nice sunny, cooler day, with some time to work on the pipe. This was the first time I had done copper soldering. I had seen it a bunch of times on TV, and felt pretty comfortable with the idea. But I've always seemed to have a little trouble getting pipe properly sealed, at least the first time. Well, I was determined to do the best job I could. I managed to unsolder the problem joint, where the copper pipe came out of the house and attached to a 90 degree curved pipe. It looked like there was a big triangle spot where solder never flowed. I suspect the original installer didn't properly clean the pipe, and the time he 'fixed' it, I think he just flowed a tiny bit more solder on the joint. After I got the pipes apart, I tried to heat and clean a little of the extra solder off the joints. Then I spent about 15-20 minutes cleaning the joints with fine sandpaper. I was a little unsure at how well I covered inside the 90 degree turn pipe, as I couldn't get a good angle on it, as it was still attached and facing the house. After sanding, I wiped and dried the joints. Then I applied a liberal amount of flux from the plumbing kit. Then I forced the pipes together, even using a rubber mallet to get a solid connection. Once again I wrapped a wet paper towel around the pipe against the house, to reduce the chances for problems with heat or flame affecting the house. The directions say heat the joint until the flux sizzles. I heated it a bit more than that. I applied a liberal amount of solder. Then I heated and added a little bit more. I closed off the relief valve outside, then went inside, down to the basement to put on the water to the sprinkler pipe. At first I put it on low pressure and went outside to check. It looked like it was holding. Then I went back down and turned on the value to fully open. When I went back outside, it looked good. It also seemed to hold up well to Sunday morning's 5 zone cycle of watering. It would appear that my first try working with soldering copper pipe was a success! (Pats self on back :) ).

Also this weekend, we took the kids to see Yu-Gi-Oh! the movie. My eldest son, who is interested in this, enjoyed the film. The rest of us found it loud, and not great. It was a oriental animation about a character from a kid's card game. That means the film was filled with low action animation, mostly just pans and zooms of a static cell, with the occasional mouth movements, and rarely fully animated scenes. I remember as a kid liking speed racer, which was the same animation style. But then the plot was about reawakening of an ancient battle of Egyptian gods played out in a card game. Which made it pretty hard to watch if you aren't into the genre. And then the narration was pretty hard to take too. It was trite, pretentious and dumb. A number of times my wife and I just looked at each other with exasperation, or even corrected the narration, it was so contradictory. So while my eldest son liked the movie, I found it overwhelming and filled with drivel.

After the movie, we took advantage of it being an even-water ration day and washed the cars.

1 comment:

Keith said...

Oh yeah - and I also used some bleach and wet-vaccing to deal with a little odor problem left over from the water that came in the last time. It looks like it worked, as the basement no longer has a 'wet' smell. Thank heavens for white carpet.