Optocouplers and elbows
After a break during the surgery stuff, digging back into electronics.

Irritated by the failure of digital audio to break out of linearity, decided to build a tube-based audio compressor and normalizer.

Found an interesting device, but not a usable schematic, in this PDF of 'Audio' magazine, Nov 1961. The rest of the magazine turned out to be much more interesting than the compressor!

1961. Golden age for equipment, shitpile age for music. Classical was Brahms and Wagner, played with the same vigor and sharpness and precision as a drunk snail slogging through hot glue. Only the conductor counted, and all the conductors were psychotic civilization-destroying modernist maniacs who HATED structure and pattern and humanity. The mission of a conductor was to FORCE reactionary retard audiences to swallow avant-garde brain poison and DIE DIE DIE.

Most interesting item was an article by John Campbell, editor of Analog Sci-Fi mag. (p 52 of PDF.) Campbell was arguing against the sine/linear approach to sound. Got everything right. Understood the hearing and speech mechanisms correctly, which very few "scientists" did at that time. His argument didn't change anything.

Shepardson already got it right in 1901. His argument didn't change anything.

Engineers of all sorts and "scientists" of all sorts and "economists" have always been stuck in linear mode, even when they are perfectly capable of handling the non-linear math.

In fairness, Campbell's specific complaint was overblown at the time. Analog audio did a pretty good job of matching the non-linearity of our hearing, and the engineers of that time did an equally good job of understanding and cultivating non-linear behavior. Tubes are natively non-linear, and volume control pots were built to give a log-shaped response.

All of this has dissolved in the digital era. Now Campbell's complaint is understated. Everything, including the volume control sliders on players and computers, is linear. There are ways to do volume compression in software, including my effort which works fairly well; but it's not available as a standard part of players. Even when it works, it doesn't work as well as analog compressors.

Thus my impulse to build an electronic compressor.

= = = = =

WHY is linear so dominant in technology? Nature is totally non-linear.

Oddly, non-linear physical mechanisms were better understood 100 years ago. This 1901 book gives a clear picture of how a 'bent lever' or bell crank provides a log-shaped response. Printing presses used complex sets of non-linear levers to apply hefty force for a brief part of the cycle.



Polistra demonstrates a bent crank in her new printshop/mill. Polistra is moving the lever back and forth linearly, not sinusoidally. The orange ruler shows the effective length of the short arm. This length is basically the cosine of the angle. It starts moving slowly, then gains some speed toward the upper end of the stroke. Happystar's size represents the lifting or pulling ability of the short arm. This varies with the reciprocal of the effective length, so it's sharply non-linear. Much more force is available at the upper end of the stroke where the travel is slowest. This is exactly the action you need for a press or paper cutter, so it's not surprising that many simple presses and cutters have a lever like this.

A crankshaft behaves the same way, though it's harder to see because the long lever is sort of 'implicit' in a crankshaft. A camshaft does NOT behave the same way; it applies the same force at all angles, or more precisely it doesn't apply force at all. A camshaft simply provides a limit for the motion of its follower, and springs or gravity apply the force.

School science and physics classes in the '60s didn't mention bell cranks. They stopped at linear levers, because everything had to be linear. A full hands-on understanding of non-linear cranks would have provided a splendid starting point for non-linear electronic devices and non-linear sensory response.

For an even more familiar analogy, you can start with your own bones and joints. We have four definite bent cranks that we use all the time. Knees and elbows. (Other joints have some bentcrankness but it's more subtle.) Designed by Nature for a purpose opposite to the printing press. Kick and punch. Start with maximum force to overcome inertia, end with maximum speed.

Labels: 1901, Experiential education, Grand Blueprint

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