Hackaday Links: September 17, 2017


Mergers and acquisitions? Not this time. Lattice Semiconductor would have been bought by Canyon Bridge — a private equity firm backed by the Chinese government — for $1.3B. This deal was shut down by the US government because of national security concerns.

[Jan] is the Internet’s expert in doing synths on single chips, and now he has something pretty cool. It’s a breadboard synth with MIDI and CV input. Basically, what we’re looking at is [Jan]’s CVS-01 chip for a DCO, DCF, and DCA), a KL5 chip for an LFO, and an envelope chip. Tie everything together with a two-octave captouch keyboard, and you have a complete synthesizer on a breadboard.

As an aside relating to the above, does anyone know what the cool kids are using for a CV/Gate keyboard controller these days? Modular synths are making a comeback, but it looks like everyone is running a MIDI keyboard into a MIDI-CV converter. It seems like there should be a –simple, cheap– controller with quarter-inch jacks labeled CV and Gate. Any suggestions?

World leaders are tweeting. The Canadian PM is awesome and likes Dark Castle.

Way back in July, Square, the ‘POS terminal on an iPad’ company posted some data on Twitter. Apparently, fidget spinner sales peaked during the last week of May, and were declining through the first few weeks of summer. Is this proof the fidget spinner fad was dead by August? I have an alternate hypothesis: fidget spinner sales are tied to middle schoolers, and sales started dropping at the beginning of summer vacation. We need more data, so if some of you could retweet this, that would be awesome.

Remember [Peter Sripol], the guy building an ultralight in his basement? This is going to be a five- or six-part video build log, and part three came out this week. This video features the installation of the control surfaces, the application of turnbuckles, and hardware that is far too expensive for what it actually is.

Sometimes Square is Square: Basic Machinist Skills

Is it possible to make an entertaining video about turning a cube of aluminum into a slightly cubier cube? As it turns out, yes it is, and you might even learn something along with the sight gags and inside jokes if you watch [This Old Tony] cover the basics of squaring up stock.

Whether you’re working in wood or metal, starting with faces that are flat, smooth and perpendicular is the key to quality results. [Tony] is primarily a machinist, so he works with a nice billet of aluminum and goes through some of the fundamental skills every metalworker needs to know. When you’re working down to the thousandths of an inch it’s easy to foul up, and tricks such as using a ball bearing between the vise jaws and the stock to prevent canting are critical skills. He covers tramming the mill, selecting which faces to cut and in which order, and ways to check your work on the surface plate and make any corrections if and when things go wrong. Look for cameos by fellow machinist [Abom79] and [Stefan Gotteswinter], including one with [Stefan] in a very compromising position. But a ball in a vise and no [AvE] reference? C’mon!

[Tony] makes a potentially tedious subject pretty entertaining by keeping things light, and we appreciate both the humor and attention to detail. He’s turned out some great videos that we’ve covered before, like making your own springs or a shop-built boring head, and his stuff is really worth checking out.

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Rainy Day Fun by Calculating Pi

If you need a truly random event generator, just wait till your next rainstorm. Whether any given spot on the ground is hit by a drop at a particular time is anyone’s guess, and such randomness is key to this simple rig that estimates the value of pi using raindrop sensors.

You may recall [AlphaPhoenix]’s recent electroshock Settlers of Catan expeditor. The idea with this less shocking build is to estimate the value of pi using the ratio of the area of a square sensor to a circular one. Simple piezo transducers serve as impact sensors that feed an Arduino and count the relative number of raindrops hitting the sensors. In the first video below, we see that as more data accumulates, the Arduino’s estimate of pi eventually converges on the well-known 3.14159 value. The second video has details of the math behind the method, plus a discussion of the real-world problems that cropped up during testing — turns out that waterproofing and grounding were both key to noise-free data from the sensor pads.

In the end, [AlphaPhoenix] isn’t proving anything new, but we like the method here and can see applications for it. What about using such sensors to detect individual popcorn kernels popping to demonstrate the Gaussian distribution? We also can’t help but think of other ways to measure raindrops; how about strain gauges that weigh the rainwater as it accumulates differentially in square and circular containers? Share your ideas in the comments below.

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Make Math Real with this Analog Multiplier Primer

Remember learning all about functions in algebra? Neither do we. Oh sure, most of us remember linear plots and the magic of understanding y=mx+b for the first time. But a lot of us managed to slide by with only a tenuous grasp of more complex functions like exponentials and conic sections. Luckily the functionally challenged among us can bolster their understanding with this demonstration using analog multipliers and op amps.

[devttys0]’s video tutorial is a great primer on analog multipliers and their many uses. Starting with a simple example that multiplies two input voltages together, he goes on to show circuits that output both the square and the cube of an input voltage. Seeing the output waveform of the cube of a ramped input voltage was what nailed the concept for us and transported us back to those seemingly wasted hours in algebra class many years ago. Further refinements by the addition of an op amp yield a circuit that outputs the square root of an input voltage, and eventually lead to a voltage controlled resistor that can attenuate an input signal depending on its voltage. Pretty powerful stuff for just a few chips.

The chip behind [devttys0]’s primer is the Analog Devices AD633, a pretty handy chip to have around. For more on this chip, check out [Bil Herd]’s post on analog computing.

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Hacker’s Toolbox: The Handheld Screw Driver

The handheld screw driver is a wonderful tool. We’re often tempted to reach for its beefier replacement, the power drill/driver. But the manually operated screw driver has an extremely direct feedback mechanism; the only person to blame when the screw strips or is over-torqued is you. This is a near-perfect tool and when you pull the right screwdriver from the stone you will truly be the ruler of the fastener universe.

A Bit of Screw Driver History:

The kind of fun you can have with really cheap bits.
The kind of fun you can have with really cheap bits.

In order to buy a good set of screw drivers, it is important to understand the pros and cons of the geometry behind it. With a bit of understanding, it’s possible to look at a screw driver and tell if it was built to turn screws or if it was built to sell cheap.

Screw heads were initially all slotted. This isn’t 100 percent historically accurate, but when it comes to understanding why the set at the big box store contains the drivers it does, it helps. (There were a lot of square headed screws back in the day, we still use them, but not as much.)

Believe it or not the "Robertson" screw came out before the phillips. Robertson just hated money and didn't want to license his patents. So it's only now that they're in common use again.
Believe it or not the “Robertson” screw came out before the Phillips. Robertson just hated money and didn’t want to license his patents. So it’s only now that they’re in common use again.

Flat head screws could be made with a slitting saw, hack saw, or file. The flat-head screw, at the time, was the cheapest to make and had pretty good torque transfer capabilities. It also needed hand alignment, a careful operator, and would almost certainly strip out and destroy itself when used with a power tool.

These shortcomings along with the arrival of the industrial age brought along many inventions from necessity, the most popular being the Phillips screw head. There were a lot of simultaneous invention going on, and it’s not clear who the first to invent was, or who stole what from who. However, the Philips screw let people on assembly lines turn a screw by hand or with a power tool and succeed most of the time. It had some huge downsides, for example, it would cam out really easily. This was not an original design intent, but the Phillips company said, “to hell with it!” and marketed it as a feature to prevent over-torquing anyway.

The traditional flathead and the Phillips won over pretty much everyone everywhere. Globally, there were some variations on the concept. For example, the Japanese use JST standard or Posidriv screws instead of Philips. These do not cam out and let the user destroy a screw if they desire. Which might show a cultural difference in thinking. That aside, it means that most of the screws intended for a user to turn with a screw driver are going to be flat-headed or Philips regardless of how awful flat headed screws or Philips screws are.

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