Category Archives: Electronics

A few months ago, in an old issue of Make Magazine I saw instructions for building a soldering fume extractor, to keep you from breathing in the nasty fumes that solder produces when melted. In the article they built it all inside an Altoids mint tin, powered by a pair of 9V batteries. Then, a couple of weeks ago at a Michael's I saw a Darth Vader head lunchbox. I picked it up due to it's low price and high geek factor, assuming I would eventually think of something to do with it. Yesterday the two ideas came together - I cut out mouth of the Vader helmet, wired in a power regulator, switch, and a 12V fan, and built my own much cooler fume extractor. It works great, too!

As promised, here are the details of the photobooth I built for our Father's Day Cookout. This first pic shows the photobooth box that houses all of the electronics. The big red button on the front lights up (even though it isn't lit in this picture). Once you push that, the green "pose" LED starts blinking - when it starts blinking fast, it's about to take a picture. Once all four shots have been taken, the red LED lights up during the assembly and printing process. One of the things I'd like to improve before next time is speeding up that assembly process - it seems to take too long. Also, I'd like to paint the box a little more interestingly. I ran out of time to do much besides a black satin paint job and some letter stickers - but once I get the enthusiasm to work on it again I'd like to do some kind of custom paint job on the box - maybe even try some silkscreening again.

I built the booth itself just from PVC and curtains - but I think I am going to make a few changes before I use it again. I need to make it a little taller, so that it isn't so hard to dial the camera in to exactly the right distance to not be able to see the top bar. Also, I'd like to come up with some system that will allow for multiple backdrops - and easy switching between them. This next picture shows the internals of the electronics box.

Here is what's inside:

1) Raspberry Pi: The Raspberry Pi was configured per this instructable - Raspberry Pi Photobooth Controller. I had to do a few things differently than listed in the Instructable - mostly I had some Linux permissions problems, and I was never (so far) able to get the script to run successfully at startup.

2) Camera: The camera is controlled via USB, using the gphoto2 package under Linux. I camera doesn't have a DC input, so I make a 'fake' battery pack using some dowels and a DC adapter so that the camera could stay powered all the time. One annoying thing is that I can't adjust the flash or zoom settings on the camera while it is plugged into the Pi, but once you reconnect the camera to the Pi all the settings revert back to defaults. Which basically means I could never get the flash to stay disabled, and instead of zooming the camera I had to move the whole box closer to the chairs in the booth. Annoying - hopefully I will find a way to deal with this with a little more tweaking.

3) Photo Printer: Just a Canon Selphy photo printer - because that's what they had at Best Buy. Works pretty well, though. Only downside is the paper and ink cartridge need to replaced every 36 prints. Which means that if it were used more heavily at the party I would have needed to babysit it a lot more. As it was, it wasn't used as much as I had hoped, but that's mostly because I didn't do a good job of spreading the word that it was there to be used. Next time I will make sure everyone knows right from the start.

4) LED Control Board: I built a little LED control board for switching power for the big red button, plus the two status LEDs. This board connects to the GPIO pins of the Raspberry Pi.

5) USB Hub: The Raspberry Pi can't handle power-hungry peripherals on its USB ports, so you've typically got to connect up a powered USB hub.

6) Power Strip: Not much to say here - everything needed to be plugged in, so it made sense to include one. In the distant future it would be nice to rewire everything in here so that it can all be run off of a single power input to the box, and then regulated down for the individual devices. But I consider that a back-burner luxury for now.

I built a Raspberry Pi-based photobooth in time for the Father's Day Cookout - I plan to show the technical details of the booth in the next post. But below are some of the photos it took. I've still got a few kinks to work out with the software, and I think next time I will use more light and a more neutral-colored background - this came out a little on the yellow side overall. But still, it was loads of fun! Everyone really seemed to love the bucket of props - I will have to find a lot more for next time!

One of the first projects I tacked with my new workbench is something that I've been promising Sean for a long time - a stand-up arcade machine. We had one in Texas, but had no room for it in the new house and I had to get rid of it. Now with a modern LCD TV (as opposed to giant old-school tube) and a Raspberry Pi inside (rather than a full tower PC) I was able to build one both inexpensively and a lot lighter and shallower than the original. All it needs now is the bezel glass over the screen to hide the last of the wood, and then it will be done. I don't think we're going to bring it up to his room until after the cookout, though - I want to give everyone a chance to enjoy it before it goes upstairs.

I needed another workbench that wasn't in the garage, that I could use for tinkering around with electronics projects. The problem is that the garage is too cold in the winter, and all the sawdust is bad for the type of stuff I'd like to work on. So I decided to build a workbench in the basement, and what you see below is the result.

This past weekend I also started working on the software to control the light grid. For now, I just tried some very simple things - rough versions of alphabetic character, and one very simple fireworks-style effect (both of which could be significantly improved. I've got lots more that I want to do, but this was a start just to give me an early fix of the awesomeness. :)

And below are a pair of short videos of each of the two things I mentioned. This first shows the letters - the example sentence I picked had Sean cracking up. The second shows the fireworks-style effect, which could use a lot of work - especially in the smoothing and fade-out department. I think I need to tail off the color values instead of trying to play with the brightness setting to get a better fade.

This past weekend I started working on the enclosure for the grid. I used some curly maple I'd had sitting around the shop for the last decade. :) It was a piece that has always been too small to make any furniture out of, but too nice to burn or throw away. So I made a nice little mitered box to hold the grid. For the diffuser to go in front of the LEDs, I borrowed an idea I saw online that actually ended up working perfectly - a white plastic cutting board. The enclosure got a coat of teak oil for a finish, which will later be followed up by some polyurethane - but I couldn't wait the three days for the oil to cure, so I mounted the grid in the enclosure to start playing around with it. In the right hand photo, you can see the enclose from the back (with the back panel removed). The Arduino is in the bottom center of the photo. Eventually, it will be mounted inside the enclosure as well, but I'm going to wait until after I get the polyurethane on before I mount it, just in case.

The first step on my new project was to cut up the original string of Christmas lights, rip off the bulb covers and mounting tabs, mount them in a piece of plywood drilled with a grid of holes, and wire everything back up. This is what I worked on for a few hours each weekend in February. After a few mishaps and bad connections, I managed to hook it all back up to the original controller (that came with them) and a new, beefier power supply (that could drive both of the 25-light strings I had spliced together).

I've started a new project at home for fun. I've wanted to start playing around with an Arduino microcontroller for a while now. A few months ago, I came across several online projects (like this one and this one) involving using the Arduino to control a new style of Christmas lights made by GE. This Christmas lights are composed of a string of RGB (red-green-blue) LED modules that can be used to create any color of the rainbow. Each LED module on the string is individually controllable, and the stock remote that comes with the lights can only do a dozen or so patterns - and most of them are fairly boring. So - similar to the link I mentioned about - I want to cut up a string of modules and arrange them in a 7x7 grid, build a nice wooden enclosure for them, and display various pattens on the grid based on different events. For example, maybe I could make fireworks on the display when I receive an email. Stay tuned for future posts - I've actually gotten a little ways on this project, I just haven't gotten the photos together yet.

Well, it's been a few months since we started using the HTPC, and the verdict is in - we love it. It passed the wife-acceptance-test, which is the critical tipping point for any geeky husband to get one of his projects into the living room. It's funny though - we are using it differently than I had anticipated. Originally, I figured that the features we would use the most would be games (for me) and movies (for Lori). But it turns out that the feature that gets the heaviest workout is recording shows for the kids. We has actually turned out to be a lifesaver for our bedtime routine - I could only have watched the same dozen or so "goodnight shows" so much longer before I would have snapped. Now, we've increased the size of our library of kid's shows dramitically. But the feature that Lori and I are having the hardest time adjusting to is the fact that we can pause live TV. It must just be all those years on conditioning - we still wait for commercials if we need to get up for something. And on the very rare occasion that we do remember that we can pause, we both feel so high-tech and futuristic, even though any redneck with a TiVO has been doing this for a long time.