Day: August 29, 2016

Building Better Tube Amps With Heathkit Parts

August 29, 2016 by 14 Comments

[Justin] had been trying to find a good tube amp for years, but all the best examples were either expensive or a complete basket case. Instead of buying a vintage stereo tube amp, he decided to build his own using the guts of a Heathkit AA-100, a popular tube amp from the 60s and 70s that doesn’t have a great reputation for sound quality.

This project was based on an earlier project from a decade ago that replicated the very popular Dynaco ST-70 tube amp from parts taken from the Heathkit AA-100. The schematic for this conversion was readily available on the usual tube head message boards, and a few PCBs were available for the input stage.

With the schematic in hand, the next thing for [Justin] to do was get a nice enclosure. High quality tube amps are valued as much for their appearance as they are for their sound quality, and after giving his father-in-law a few sketches, a cherry hardwood chassis stained in a beautiful golden brown appeared on [Justin]’s workbench.

The big iron for this new tube amp was taken directly from the old Heathkit, and a few hours in front of a mill netted [Justin] a chassis panel drilled out for the transformers and tube sockets. The rest of the project was a bit of assembly, point-to-point wiring, and wire management giving [Justin] a fantastic amplifier that will last for another fifty years until someone decides to reuse the transformers.

Hyperuniformity — A Hidden Order Found In The Greatest Set Of Eyes

August 29, 2016 by 62 Comments

Of all the things evolution has stumbled across, the eye is one of the most remarkable. Acting as sort of a ‘biological electromagnetic transducer’, the eye converts incoming photons into electrical and chemical spikes, known as action potentials. These spikes then drive the brain of the host life form. Billions of years of natural selection has produced several types of eyes, with some better than others. It would be an honest mistake to think that the human eye is at the top of the food chain, as this is not the case. Mammals underwent a long stint scurrying around in dark caves and crevasses, causing our eyes to take a back seat to other more important functions, such as the development of a cortex.

There are color sensitive cones in all eyes. Mammals have three types of cones, which are…wait for it…Red, Blue and Green. Our red and green cones are relatively recent on the evolutionary timescale – appearing about 30 million years ago.

The way these cones are distributed around our eyes is not perfect. They’re scattered around in lumpy, uneven patterns, and thus give us an uneven light sampling of our world. Evolution simply has not had enough time to optimize our eyes.

There is another animal on this planet, however, that never went through “the dark ages” as mammals did. This animal has been soaring high above its predators for over 60 million years, allowing its eyes to reach the pinnacle of the natural selection process. A bald eagle can spot a mouse from over a mile away. Birds eyes have 5 types of light sensitive cones – red, blue and green like our own. But add in violet and a type of cone that can detect no light, or black. But it is the way these cones are distributed around the bird’s eye that is most fascinating, and the subject of today’s article.

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Let’s Put A Hackerspace In Prison

August 29, 2016 by 26 Comments

The Hack42 Hackerspace in Arnhem, Netherlands is one of the best hackerspaces we’ve ever seen. After taking over a decommissioned military base, the Hack42 crew has filled a compound rimmed with razor wire with eclectic gizmos, tools, and a community that keeps growing the space. At this year’s EMF camp, Hack42 member [jos] laid out his plan to found the ultimate Hackerspace. He’s going to put a hackerspace in prison to create the ultimate hacker village, a monument to technomancy, and an anti-panopticon panopticon.

[jos] recently noticed a very large, very old prison — currently used to house refugees — went up for sale. This prison, located in downtown Arnhem, Netherlands is a panopticon, a concept for prisons popularized in the 1800s, with most designs based on a circular structure with prison cells along the diameter around the circumference and a guard house in the center. This gigantic building is 55 meters (180 feet) in diameter, and 46 meters (150 feet) tall at its highest point. This gigantic prison dome could contain the White House inside its walls, a few blue whales, and could almost fit a space shuttle stack under the dome (the orbiter itself would fit just fine if there were a door).

The ambitious vision for this prison-come-hackerspace is a permanent venue not unlike other hackercamps where hackers can stay for weeks or months to build a project, a venue for like-minded people to meet up, and a place for students to do graduation projects under the wings of academic leadership. A community is one thing, but this former prison would also be the largest hackerspace by enclosed volume, opening it up to some very cool, very large builds. Inter-office quadcopter mail was mentioned in the talk.

[jos] is looking for comments, ideas, and remarks via this Google form to, “convince the money-people to fork over the funds.” If you’ve ever wanted to contribute to something big, this is your chance.

Raspberry Pi Hive Mind

August 29, 2016 by 34 Comments

Setting up a cluster of computers used to be a high-end trick used in big data centers and labs. After all, buying a bunch of, say, VAX computers runs into money pretty quickly (not even counting the operating expense). Today, though, most of us have a slew of Raspberry Pi computers.

Because the Pi runs Linux (or, at least, can run Linux), there are a wealth of tools out there for doing just about anything. The trick is figuring out how to install it. Clustering several Linux boxes isn’t necessarily difficult, but it does take a lot of work unless you use a special tool. One of those tools is Docker, particularly Docker Swarm Mode. [Alex Ellis] has a good video (see below) showing the details of a 28 CPU cluster.

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