crazy project

[gfish]

So, yeah, I decided I needed a crazy project to be working on to keep away the "my research is going nowhere" depression feedback loop. I just do better when I have a crazy project to be working on -- my alignment is quixotic good, after all.

The idea: a pair of sunglasses with circular lenses with polarized sheets that can be rotated to change the opacity. Done with brass gears. And a small servo to automate the rotation. And a light sensor so it can compensate for changes in illumination.

It's just within my very limited production capabilities, with 99% of my shop in storage. The frame I'll cut out by hand, using a jeweler's saw. Which will be a pain, but I've done more tedious things in the past and lived to tell of it. And it will be in keeping with the overall steampunky feel of the things.

After a series of tragicomic events, I got the circuit working tonight. It's a simple little astable 555 timer circuit, sending out a variable PWM signal to control the servo. It has a potentiometer in parallel with the photoresistor, so I can adjust the gain. (I have no idea how much regular adjustment will be annoying...) I'll also add a cut-out switch to the light sensor, so the rotation be directly controlled manually with the pot. Along with the overall power switch, that will make for 4 inputs to control my sunglasses, which seems like a reasonable UI to me. All this will probably mount along with the power source on my vest, with just the servo control leads going up to the glasses themselves.



Once I get some direct sunlight, I can work out roughly the range of motion I should see under normal conditions. That will let me decide on a gear ratio (it looks like getting a full 90 degrees rotation on the lenses won't be practical, but I can live with that), thus fixing the size of the gears, and I can finally finalize the frame design. Probably too late to order stuff for this weekend, sadly, but there is no real hurry. I just want it all done by Burning Man, natch.

Comments

[neuro42.livejournal.com]

That's actually pretty cool.

[lostmachine.livejournal.com]

Ah FUN. This is supper cool, I really like the practicality of it. The goggles I made do nothing. http://www.lostmachine.com/projects/steampunk/index.html

I am just now getting into control systems for my project. It has always been on the horizon but hadn't been getting closer until last week when I built a Arduino clone on a DorkBoard.

http://dorkbotpdx.org/wiki/dorkboard

Please keep posting updates as you build. I really want to see these.

[neuro42.livejournal.com]

also, are you going to use photographic polarizing filters (premounted in nice rotating mounts)? You should make sure at least two of the four are non-circular-polarizers if so.

[gfish.livejournal.com]

I think mounting and driving those would be too hard. (Also, much more likely to jam when hit with a week of playa dust. Precision machining isn't my friend in this case.) I'm just going to get ~1.8" hubless gears, cut out most of the center, and glue polarizing sheets in.

[adularia.livejournal.com]

Purposeful drawings are always beautiful.

[gfish.livejournal.com]

Once I draft the final designs, I'll definitely post them. Kind of fun, doing it entirely oldschool, all the mounting holes determined entirely geometrically with a compass and straight edge.

[hsifyppah.livejournal.com]

The frame I'll cut out by hand, using a jeweler's saw.

If you want to use some fancier-pants tools, you're totally welcome to come to Joe's parents' with us any Sunday. I don't know what tool would make it less tedious, but probably Tom has three of them, whatever it is.

[gfish.livejournal.com]

For the level of precision I want, the only other options are CNC mills, laser cutters, etc. Which I could get access to in Seattle, if I really wanted to. For now I'm going to stick with doing it oldschool -- consider it part of my passive-agressive attack on bad steampunk. :)

I will need a drill press at some point, though, so I might take you up on the offer after the frame is all cut out.

[hsifyppah.livejournal.com]

consider it part of my passive-agressive attack on bad steampunk.

Hah! I can get behind that. :)

[vixyish.livejournal.com]

<3

[randomdreams.livejournal.com]

I'd like to see what sort of servo driver you're using.

This quarter's MAKE had a superb servo amplifier: they tore apart a standard RC amp and hooked the output through transistors to a couple monster relays. The servo input was a multi-turn pot. They hooked all this to a 12v scissors jack so you can precisely position 2 tons with the twist of a pot.
*love*

[gfish.livejournal.com]

Pretty much exactly the one here (http://www.geocities.com/bourbonstreet/3220/servobasics.html), but with a photoresistor from pin 7 to R2, and the resistor and capacitor values tweaked to use a 50K pot. Nothing very advanced at all, really. Anything more and I'd want to flee to the safety of a microcontroller. (Like, I wish I could easily add a microphone and have it pulse to maximum opacity for a second or two after a loud noise -- peril-sensitive sunglasses! But doing that in parallel with everything else in circuitry? Not going to happen.)

[ilmarinen.livejournal.com]

Love the idea, something I've vaguely thought should exist for a long time. Make them solar powered also? :D

-B.