Posts Tagged ‘Hardware’

Varactor Based Video Synth Prototype

Saturday, December 5th, 2009

My first winter in Brooklyn I made this biz. It’s a video synth that I put together on a little Narrat1ve-specific protoboard (or as I call it, the Narrat1ve Big Wizard). It’s different than the last one in lots of important ways. It’s NTSC, and generates all its own sync and blanking pulses in software (that mess is coded in C for the AVR). I spend a lot of time looking at Bruce Land’s stuff, as well as the always-on-point Owen Osborn.

More importantly I figured out how to get a continuously variable phase shift of the color carrier (analog color!) using varactor diodes! This was a big step in making stuff that looked cool. Varactors are not ideal in a lot of ways, but they are sure simple.

I slapped this guy together for a talk I gave at La Superette that I got asked to do by the inimitable Kyle and Tali from Lovid. They were really cool about this talk and I had a great time!

This really beautiful and simple proto has since been deprecated by the monsters II’ve made since and is hanging around in some drawer or other. Sad, really. Ask Too $hort about it.

xo
TB

Dancing Stands, Inappropriate Toaster Use

Sunday, November 29th, 2009

This labor of love and money was also for Cory. Basically, there are these two weird Chinese merchandise stands that get sold at places like Spencer’s, and Cory was like, make one go a few percent slower than the other one. I think originally he was thinking stepper motors or something which is why I got involved, but it was a lot more low-level (in a wedge-screw-pulley-inclined-plane kind of way and not so much an assembly language kind of way) than that.

Inside one of these things is a reversible synchronous AC motor with a toothed belt linkage. A quick test with the Variac proved that, yes, their speed was independent of input voltage. Turned out the easiest way to get the speed differential was to pull the original transmission parts and replace them with XL drive pulleys and belts. The OG stands use a 3mm (I think) Chinese pitch system which is kinda hard to find around these parts. McMaster saved the day as usual but now I get my goodies from my pulley people at B&B Manufacturing who have likely forgotten more about power transmission than I ever hope to know. One thing about McMaster, they aren’t shy about leaving other peoples’ labels on their parts :-)

Doing this meant a lot of cutting and tapping, which is fun for me because I rarely get to do it professionally. To wit:

I had to drill out the pulleys (they’re made for 0.250″ shafts and the shafts in the stands are 7mm) and got all noided about leaving tap magic on them because I was worried about the belts not liking it. This was part of the washing/drying process and won me zero points with my housemates.

Apparently A Slow Month

Tuesday, October 27th, 2009

The only thing I can find that I did during the month of October in 2009 that did not involve an NDA or corporate clients was apparently retrofitting my workbench chair with hot pink racing casters from McMaster and undoubtedly listening to this a lot.

xo
TB

Remoc, cursed bringer of joy

Tuesday, September 22nd, 2009

This benighted ogre is a wonder put into this world for the express purpose of making sick children smile. He lives in the lobby of the Comer Childrens’ Hospital in Chicago, and was a really nice present that my old toy company donated. I more or less did the work for free in a really short time, and it was good experience.

Problem is there was a lot I didn’t know in 2005 (though it did not stop me from TRYING to design some complicated sensors) and in the time since then I’ve spent about a million hours putting band aids on less-than-ideal systems.

This is a picture of his brain extracted, waiting to go somewhere. I knew I had to fix it, I wasn’t sure when that would be.

WTPA v1.0 Up and Running, And Hosed (a little). Also Dorkbot.

Thursday, April 9th, 2009




Oh Snap! There’s the goofy silkscreen I promised last time. But don’t worry, it gets better :-)

So I’ve done my best with the above Still-Life-With-Nerd collage to try and convey, in a meaningful visual way, all the cool stuff that’s happened with WTPA since last week. One really perceptually-difficult-to-convey-yet-great thing is that I’ve put my proper rent-paying clients on hold for the time being to make room for this project full time. It’s scary, but it feels really good! And as rebellion goes I suppose it beats buying a Camaro.

Outside of that, the BOARDS ARE HERE! Sort of.

The bad news is, I found a copper bug (my fault) pretty much right away. With as many hardware revisions as I’ve done this was really embarrassing. It led to a natural dilemma — it was a small bug that could be easily fixed with an exacto knife and some jumper wires, so should I you pass that fix off to you, the kit builder, or should I pony up for an ENTIRE NEW SET of boards so that they’d be perfect?

I debated, then reordered them. This also allowed me to fix a half a dozen little cosmetic and noise-floor / routing things that I wasn’t happy with anyway. I wasn’t nuts about dropping another grand on boards, but I’d be less happy knowing that the final kits were going out half-assed. You can’t pay too much for pride :-)

Silver Lining: This now allows me to sell bare boards, which a ton of people have asked for. Originally I hadn’t planned to do this, but now I can sell the flawed boards (for cheap) with an errata sheet to those among you who are exceptional broke asses and not mess up the math and parts counts for the complete kits. It’s a small consolation, but it’s better than making them drink coasters.
Cosmetically, the boards are flawless! I got a not-quite-perfect board from PCBCart before this (for another job) and let them hear about it, and they bent over backwards to make this one dead-on.

Taiwan Alpha also came through — the pots (all 2000 of them) showed up from China early and perfect.

Then there was Dorkbot which was a blast. Above you can see me in front of a page of C code (looks like the ISR) apparently casting some kind of spell.

People geeked out, I gave away some free PCBs, I laughed, I cried, it was better than Cats.

Finally, social business done, it was back to the Fortress of Solitude with some espresso and a dream. Two great things have come out of this so far:

One:

WTPA now has a banked sample system! This means that instead of holding a loop, WTPA can hold an arbitrary number of loops (theoretically, anyway) and can do anything it is able to do to any or all of those loops independently and all at the same time.
Practically speaking, I’ve pinned that “arbitrary” number at 2 :-). There was a lot that went into this! A huge portion of the code had to be re-written — basically all the audio and memory handling parts. The audio system now grabs data from the ADC and passes it to however many “virtual samplers” for recording, and then sums together whatever output they have before putting it back onto the DAC. Better still, the different banks can use different clock sources! Meaning that you can be triggering events with midi and controlling pitch arbitrarily one one bank, and twiddling knobs and generally being a caveman on the other, with a totally independent samples.
By far the hardest part though was having to wrap my head around implementing a memory manager (ever think you’d have to write malloc? Me neither) which was quite challenging. To be honest, I copped out a little, and it is because of this that WTPA uses only two banks for now.

All this cool functionality also has a totally new (and much more intuitive, I think) menu system. Finally, I’m in the midst of getting rid of “modality” in WTPA so that there’s no such thing as “MIDI mode” and “Manual Mode”. Anything you can do with WTPA you can always just do, without mucking around in a menu.

Two:

I crunched the money numbers! As of today, I know exactly how much all this crap has cost me, and therefore how much these magic beans will cost YOU, dear reader. I’m not spoiling the surprise, but I will say that although I have definitely screwed up some estimates in my time, I was pleasantly surprised with how this one came out. And you should be too.

I’ll keep you all posted on the nerdy revelations better for this last week. Don’t expect total coherence or an Infinite Jest command of grammar, but I got you. Oh, and I think I’m going to LA to talk about WTPA at the end of the month, so if you’re on the West Coast come say hi! More details on that to come.

Xoxoxo,

TMB