This past Tuesday, Jeff Jensen, a long time friend of OMG was at our regular meeting to get some help with mechanical assembly and soldering of a dozen CEENBoT units. Jeff is part of a program that develops the CEENBoT robots for education and the program has been so successful that Jeff is overloaded with requests for new robots, so several OMG members jumped in to help out.

We had several other visitors, including first-time guest Chris, who promptly jumped in to help out. This really embodies the spirit of OMG, creating an environment where folks feel comfortable getting involved in whatever’s going on.

Thanks to everyone who helped out on Tuesday!

Oscilloscope Music

A few weeks back, I caught a video on AvE’s YouTube channel of graphics drawn on an oscilloscope, given an audio input. Last week, Ben, Garrick and I decided to give it a try at OMG.

According to Garrick’s research earlier that week, “older scopes” do better with this sort of thing, and OMG’s scope is plenty old. We had to do some tinkering with the settings, and the phase, eventually arriving with the left channel on Input 2, alternating vertical and External trigger (ch2). It worked best if the laptop volume was turned clear up, as it gave the best signal to noise ratio.

We’d initially hooked the scope directly to a laptop headphone jack (through a spaghetti of cables), but as Eric pointed out “To be music, there’s gotta be…music”, and no devices we had would play on the headphone jack AND the internal speakers at the same time.  We ended up hacking up a powered speaker to give us a stereo output and play both channels on a single speaker. This gives us something to feed the oscilloscope AND lets folks hear what the audio actually sounds like. In addition, it had a lot less noise than our initial mess of wires.

As for what we played, we just searched YouTube for “Oscilloscope Music”.  Someone who works with Jeff mentioned Aphex twins “windowlicker” and “songs about my cat” by Venetian Snares as two examples of spectrographic songs.

RedBull Creation 2012 Entry

RedBull Creation challenge entry. It’s a brain-wave game. The players stand on opposite sides with wireless headsets that measure brain waves. One of them presses the big red button on the back, and then as they focus the power of their minds, the arm responds to their brain wave readings, and moves back and forth according to who is focusing best. After 10 seconds the Bullduino (visible at the front in the window) checks whether the pointer is in one of the green scoring zones. If it is still in the yellow zone, it’s a tie and it just returns to center. If it is in one of the green zones the player on that side is the loser, and the ball sprays that player.

New Ring-Light

People I meet via the Omaha Maker Group often ask me what it is that I make.  I try to avoid the “Everything” answer, popularized by Jason Uher, but it seems to be sort of the truth.  Due to a renewed  interest [by people who aren't me] in things that I’m making, I’m trying to do a better job of actually driving these projects to completion, and maybe even doing a slightly better job than I otherwise might. I’m also trying to do more projects that are more “grand” in scale (for example, building a power supply, instead of a really neat custom connector; Not that either of those are really grand, in the big picture).  Below is one of these projects.

After lots of fiddling with desklamps and bounce cards every time I want to take a decent macro photo, I’d finally had it.  I started looking into buying a ring-flash accessory for my digital camera, but found them to be alternatingly pretty expensive or in the realm of “I could build that”. So I did. Read on for the details and a few more photos.

I determined early on that I didn’t want or need a flash-tube-based solution (like the one built by Patrick), which is a reflective ring illuminated by a standard photo flash.  I didn’t want to spend the money for a fancy “automatic” external flash, and didn’t want the headaches and setup associated with a cheap manual flash.

I did some initial research on running an LED illuminator on the camera’s hot-shoe trigger, but decided that it really wasn’t needed, as LEDs can just be turned on and off and don’t need to be “fired” like a xenon flash. My illuminator is powered by a simple pack of 4 AA batteries (ideally NIZN for the extra .3V).

The illuminator itself  is just 8 banks of 14 (112 total) white LEDs soldered to a piece of perf-board and a connector for power.  To make it run on 6 volts nicely (and to give me more input voltage range), I wired both halves of the LED array in parallel and then the two banks in series. I could have just put the banks themselves in parallel (and run the array on 3ish volts), but that would put my total current draw at over 800ma, which I opted to avoid.

I found a pretty neat online schematic designer, so I whipped up a schematic, in case you can’t picture what I’m saying:

From a physical standpoint, the LEDs are just soldered to the perfboard and surface-wired on the back side. I’m a bit embarrassed by my soldering job, so I won’t be posting any photos of that here.  I cut the hole in the center of the board with a few forstner bits, and finished it out with a sanding drum in a Dremel. I plan on gluing a 58mm filter ring [generously donated by Don] to the back side of the board so that it can attach to my S5′s filter adapter. I’ll probably just Velcro the battery pack to the side of the camera, as this rig is mostly for use on a tripod.

One problem I have come across is the convergence pattern on the LEDs. At distances less than about 8″, there’s a bit of a dim spot at the center of the frame. This should be correctable with some sort of diffuser and a bit of tweaking of the LEDs angle.

As for the LEDs, they were ordered from Tayda Electronics for $8 shipped ($0.04 each, plus $2 shipping). At 3.1ish volts per bank, I’m under-volting them just a bit, but they seem plenty bright.

Below is a few more pictures of the light, plus a photo of another project, demonstrating the dim spot. More photos of the device will follow, as soon as I get it into a more final form.