Friday, July 30, 2010

New York, I love you, but you're bringing me down...

Long story short, while loading up for the shoot this weekend, we left the rental car unattended, in broad daylight, on a busy street, for no longer than 5 minutes, only to return to a smashed window and a few bags missing.

Unfortunately, those bags happened to contain the director's laptop and personal effects, the cinematographer's Canon 7D, $3,000 worth of rented lenses, and associated support gear (which is not cheap), two Moon props, and all of the associated electronics. And a duffel bag full of my clothes. And my hammock.

I am kind of at a loss for words... but at least my stuff is replaceable. While it took roughly 1.5 months to develop the Moon hardware, it only took a few days to build it once I got it all figured out. And there are certainly improvements to be made for Version 2.0.

But if anyone knows a way to track a missing laptop (MAC address? anything?), or a seedy pawn shop in Brooklyn where nice cameras and MacBooks sometimes turn up, my friends would be much obliged.

In the mean time, one more picture of v1.0. This was the first LED puck light that I "hacked" apart... and it kind of shows. It wound up being the base of the Lunar Lander... note the blue smudges around the screws. I bet you've never seen someone use LocTite on an Erector Set before. I think for v2.0, I might spec my own LEDs. Forget vomit green Home Depot lights– v2.0 will actually be color correct 5600K.

Thursday, July 29, 2010

The Eagle has Landed

Ain't she pretty? The lighting is a little more consistent with the LEDs mounted more toward the center of the moon.

Note the screw at the very bottom of the frame. I drilled three holes, using five different drill bits, starting with 1/16" and going up to 5/32", in 1/64" increments, to avoid cracking the plastic. I feel like there will be a job waiting for me at BP once they see this...

This is the completed "Lunar Lander" module (it really looks like it with the legs attached :) It is secured with steel bailing wire, copious amounts of hot glue, and LocTite (actually, Permatex Threadlocker, but commonly known as LocTite). If this sucker comes apart, I will go jump in the lake myself. I just hope I don't have to take it apart to fix it... but copious amounts of solder, and hot-glue reinforced wire joints ought to prevent that from happening.

I must admit I am impressed with the strength of the hot glue, combined with its slight elasticity, to provide a very strong, but shock-absorbing joint.

I also must admit that I am NOT impressed with Home Depot and their child brand Hampton Bay, as far as product consistency goes. The first light I bought had a pretty bluish-white glow, so I bought a 3-pack to complete the pyramid. The 3-pack, however, though it came from the same shelf in the same store, has a really hideous green cast to it. We'll probably have to correct it with some Minus Green gel if we can find it... so if you buy these for your house, beware, they might have a vomit-green color cast to them... not so good for kitchen cabinet under-lighting, but might match your fluorescents!

This is a view of what was originally going to be the "dark side of the moon," but it is now lit for 360˚ coverage... in Three-Dee... so really 360^3 degrees. Right? Why not...

And finally, my way of removing solder (and hot glue) fumes from the air. Might I add beforehand, DO AS I SAY, NOT AS I DO:

Obviously, DO NOT DO THIS if you (or anyone else with keys to the apartment) is planning on taking a shower any time soon. Please note that the extension cord is knotted around the shower curtain bar, thus preventing anyone from closing the curtain completely and making it quite obvious even to the lay-person that it is not safe to shower right now, if only for the sake of modesty.

However, since the cord is knotted up high where the water should (REPEAT: "SHOULD") not touch it, it is not completely unsafe to shower with this configuration. And it is plugged into a GFCI outlet ;)

I do wish we lived in a world where jokes did not require big bold disclaimers, but, in closing, DON'T RUN EXTENSION CORDS THROUGH YOUR SHOWER, THAT WOULD BE REALLY DUMB, ESPECIALLY IF YOU ARE A PROFESSIONAL ELECTRICIAN!


Wednesday, July 28, 2010

All in a day's (month's?) work...

Today was a very busy day...

Soldered the control board. Six 100k pots in parallel might be conflating Ohm's Law and Murphy's Law, so I'll have to figure that out...

The offending area...

This one is for all my Grip Brothers (and Sisters), demonstrating the proper use of a Cardellini clamp. I do wish I had a knuckle to go in between though...

And finally, a first glimpse at an [almost] finished product :)

Tuesday, July 27, 2010

It's nice to have the right tool for the job every once in a while...

Saves you from having to literally "hack" your way through things, and makes the end result just a little bit prettier...

This is the switchboard for the LED dimmer, which I am really excited about.

Counting down, 3.5 days left to finish it...

Thursday, July 22, 2010

I miss doing sound...

But once a year I get to indulge myself at the Falcon Ridge Folk Festival, barefoot in the mud for 4 days (used to be 5; four days felt short this year...). More pictures to come...

Wednesday, July 21, 2010

The first thing I've built that I've been legitimately afraid of plugging in-

I've had a slight fear of large capacitors ever since I took apart a 220v camera flash circuit when I was a child... lesson learned.

Hence the cardboard box "blast shield" for lack of anything better... Yes, cardboard is flammable, thank you for pointing that out. But I decided I was much more prepared for a small electrical fire than for chemical burns. Safety glasses, bucket of water, and thick soled shoe (to stamp it out) at the ready, I [reluctantly] flipped the switch. Luckily my fears were much exaggerated, and nothing jumped except for the needle on the meter.

However, it's still not working right... I am getting 21.7v dc out of a 16.2v ac input... Possibly because there's no load... but until I figure out this over-voltage thing I'm reluctant to hook anything up to it...

Thursday, July 8, 2010

If I had an oscilloscope, this is what it would look like.

Sadly, though, I don't have one. So I spent the day figuring out in theory why my lights are flickering. But I think I've found the problem, through roundabout and purely theoretical equations. Right now I really wish I hadn't slept through 3 years of high school math...

Briefly, this shows 1/48 of a second, the exposure time (Tv, if you're a Canon person) for a movie camera shooting at 24 frames per second (triangle wave). The effective exposure time is when the shutter is at least 50% open, exposing light to the film/sensor (thanks M&P!).

The tall sine wave is 120vac power at 60Hz, with peaks at 120Hz. I drew all the peaks as positive, as we're only concerned with "on" and "off" here, not polarity. This is the "flicker rate" of an incandescent bulb, but they don't really flicker due to a sort of "heat momentum" that carries the light through to the next peak. LEDs, being much more efficient, however, do not have this momentum, so they are much more prone to flicker.

The very short arches are the 12vdc rectified power, with positive peaks also at 120Hz. But the taller 120v peaks are easier to see, so we'll use those for reference. The vertical axis is not necessarily to scale, as we're comparing a lot of different things here.

The gray bars represent the PWM dimmer signal, at 1kHz. The width of the bars shown is at 100% duty cycle; as the light is dimmed down, the bars would get narrower. This is the amount of time that the power is "on" to the LEDs. The positive bars are "on time" and the negative bars are "off time."

Now, for why I've spent so much time doing this: The problem is that the LEDs are flickering visibly toward the low end of the PWM dimmer (picture much narrower gray bars). This is no good for camera. I had thought the problem lied with the PWM frequency, or the fact that I broke the legs off the rectifier's smoothing capacitor.

But it appears now to be the latter. If you look, there are 2 dips of the 120Hz power within the exposure time. Even though the PWM may be up full (100% duty cycle), if the input power is rising or falling, it is not putting out 100% brightness. If we assume, like the effective shutter speed, that the LED is only effective at 50% output or greater, the gaps widen significantly, and the flicker becomes even more apparent.

The Arduino PWM can allegedly go up to 64kHz, which is great, but without a clean DC power source, it wouldn't make a difference. Too bad I exploded the replacement capacitor today... apparently there is good reason behind the adage "don't plug it in while the power is on..."

Tuesday, July 6, 2010

LED Project 1


Current scheme:


Sadly, the capacitor is no longer with us, due to an accident...

Thursday, July 1, 2010

ikea is smarter than you

Meet Patrull, our new shower alligator. We found him in the impulse purchase section of Ikea. We will be sending samples from our previous shower mat to the CDC and several university laboratories to identify exactly which plague was growing on it. But Patrull will stay clean, because he can hang up and air dry. Ikea is smarter than you.

Hello World

Testing 1 2 3...