sic transit gloria, CA3046

Earlier tonight, my good friend Old Crow told me of the passing of a long-time friend. And while others may find themselves irrevocably moved by the disappearance of a human mind from the conscious experience of this plane of existence, I source my sense of wonder from a different place: the engineer’s perspective.

When you learn about making things like amplifiers in EE class, you learn about how important it is to have matched pairs of transistors. Symmetry tends to be just as important in electronic circuits as it is in plant life: pairs of tubes supply and remove fluids from a plant leaf much the same way electrons flow through paired transistors in an amplifier. Optimal behaviour occurs when these sides respond in a balanced, symmetrical manner (in the most common cases.)

The more closely you can match the behaviour of these 2 transistors, the more symmetrical the circuit becomes. So, someone got the bright idea — what if we put more than one transistor on the same piece of silicon? Thus, the integrated circuit was born: not with the goal of putting computers on chips (or anything digital, for that matter), but with the idea of making the performance of a circuit uniform.

The earliest ICs only had simple transistors on them. The CA3046 was pure simplicity: 5 matched NPN type BJT transistors on the same chip. You could continue to build circuits the way you were used to — with resistors and capacitors on the circuit board or prototype board — and simply replace the transistors in there with matched transistors, formed from the same piece of silicon. Presto, your circuit sounded a lot better. If you went high volume, you could have your circuit burned into its own integrated circuit; many opamps (the building block of modern analog circuit design) were designed this way. Or you could create a printed circuit board, and go that way — the sort you might have seen in just about every consumer electronics product in the 1970s and 1980s.

The CA3046 (and its strange partner, the CA3096: 3 NPN, 2PNP in a single chip) helped us ring in an age of harmony. Matched pair transistors were essential to building harmonic circuits that were pleasing to the ear. The original Moog “transistor ladder” design required hand matching of transistors; were the CA3046 available then, Moogs probably would have been a lot cheaper (had they not already become a “fad.”) And so we come to my understanding and initial exposure to the CA3046/CA3096: exploration of the circuits used to create the music I so loved as a child — pioneers like Wendy Carlos, Vangelis, Larry Fast and Tomita — combined with a single class at Yale University, taught by Prof. Peter Kindlmann.

Professor Kindlmann, or pjk as we all knew him (his email alias), related device physics to something tangible onto which I could hang in the rareified Ivy League air. Suddenly electronics was about what I remembered: sitting at my little brown particle board and wood veneer desk, torturing a poor PCB away with my poor soldering gun (!!!) skills, and constructing a Heathkit digital clock or analogue, solenoid powered metronome (Oh, how I want that metronome again!) I started to make sense of all the abstract math and subatomic particle interaction. Up until that instant, when he brought together the origins of the CA3046, I felt Yale had failed me in my engineering instruction. I didn’t want to be a theoretical physicist, much as I respected (and could readily understand) the principles involved. I wanted to do something with that technology that was of use in solving a more macroscopic problem: lighting a room, carrying a human thought from here to here, making music, enriching lives. My inner humanitarian had found other outlets, through education and community outreach, but I could not see what my degree would ever do for me. My heart simply didn’t lie in the depths of the “bunny suits” (outfits you wear in transistor fabrication labs) or in digital signal processing. I needed to be as close to the human experience as possible; my projects would always be more of a component integration exercise than a wander in the forest of science.

Later I had a few missed starts trying to make circuits: a failed design for a video game emulator cartridge that was already halfway into production nearly bankrupted me, and I lost heart. I put away my skills for many, many years, always thinking that i could fall back on it if I really needed to. Now I see it’s a skill I’ve neglected for far too long, and one that can enrich my life if I only take the time to apply it artfully. Expect to read more about this in the future, whether here on livejournal or at my websites and (shameless plug).

Where was I? Oh yes, the CA3046. Prof. Kindlmann helped me connect the dots — thank you for helping me stay the course until I could believe enough in myself to explore such a project again.

It is with a heavy heart that I leave you with this last link: CA3046, TBD.

3 thoughts on “sic transit gloria, CA3046

  1. And in other exciting news…I got two speakers for the Wurli 200A from a guy on ebay selling parts from one he gave up on! $20 plus shipping. One has had a finger poke through it but I only need one, right? So, that’s the end of that chapter…for now. Looks like I’ll need to fire up a soldering gun myself. Hope all is well.

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