Category Archives: Electronics

I've recently started putting together an HTPC to go along with our new LCD TV. It's only about half-finished, but people have been asking me lots of questions about it. So I thought I'd put together a post that explains a little about it, so I'd have some explanation and pictures to share with those who ask. Basically, an HTPC (Home Theater Personal Computer) is a PC that is connected to your TV, that runs user-interface software that allow you access to a comprehensive set of features. To find out more about it and to see some pictures of it in action, hit the "read more" link below (I didn't want to clutter up the front page of our blog with all the pics).

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I recently bought some super-bright blue LEDs on eBay, in an attempt to get some brighter LEDs for my PWM lighting project without breaking the bank. When the package arrived, it was covered in Hong Kong stamps. When I had purchased them, I guess I just didn't notice where they were coming from. Not that it would have made any difference - but it was a cool surprise to get this envelope and to realize that it had come to me from halfway around the world. I took a couple of pictures of the envelope to share with everyone.

Finally got my box from Mouser, and started building up a prototype lighting module for this project. You can see a picture of the module in the first photo. It's basically 12 super-bright LEDs (4 red, 4 green, 4 blue) arranged in a circle, with a ULN2003A, ballast resistors, and a six-pin header for connecting to the main board. I'm not planning to show you the bottom, as it was my first real soldering attempt and it ain't pretty. :) I still have to write some code to allow me to communicate with this thing via RS-232 so I can change the color settings on the fly - so I haven't really tested its color range at all. But I am finding that the colors don't blend particularly well (although it's hard to tell, because the only color I've tried so far is 'white' - i.e., all LEDs on at full intensity). I've seen other projects on the web that do this kind of blending, and most of them don't seem to be having this problem. I'm not sure, but I suspect it may be because these particular LEDs have a pretty narrow viewing angle, so the light doesn't really spread out much, which is limiting the blending. Hmmm.... will have to do some experimenting soon. The last picture is with all LEDs at full intensity, but it's a little misleading. The colors don't actually blend as well as it looks like in the photo.

I've been super-busy at work lately, and haven't had much time for personal projects. But I have managed to spend a tiny bit of time here and there working with that AVR development board. I've got it controlling 8 super-bright LEDs (4 green, 4 red). The code I've written uses PWM (pulse width modulation) to control the intensity of the LEDs. I'm going to use this method to try some interesting projects using color-blending from red, green, and blue LEDs. I'm pretty much stuck right now though - I am waiting for an order from Mouser to get here. By the way, for you other folks using AVRs - where are you getting them from, and which AVR are you using? I'm having trouble finding anywhere that I can still get the 2313 that is on this development board. Do they make them anymore?

I just got an Atmel AVR microcontroller development board in the mail, and have started playing around with it. Hobbyists use these for all kinds of things - from robotics, to data acquisition devices, to lighting modules, etc. Just Google "AVR projects", and you will see what I mean. I've been interested in learning about using microcontrollers for quite a while (ever since Dirk starting building a robot with them in 2001), but for some reason I just haven't buckled down and -tried- them yet. Last night I managed to write code and wire up a circuit to light a single LED. This would be the equivalent of a "Hello World" program in another programming language. It's a humble beginning, but I've already got ideas for lots of cool projects I can build with this thing!