Hackaday Links: March 12, 2017

The world’s first public installation of a solar roadway caught fire or something.

Hey hardware nerds in the UK! Nottingham is having its first monthly hardware meetup. This get together is being put together by [Spencer], creator of the extremely popular RC2014 Homebrew Z80 computer kit. The meetup is free, and it’s happening this Tuesday.

[danjovic] sent in a link to this YouTube channel of a guy building stuff out of PVC sheets and CA glue. There’s a lot of stuff in here from a PVC tripod to instructions on how to get PVC sheets out of PVC pipe. Small warning: this is PVC, and it will kill you instantly, for reasons we can’t yet determine. Additionally, he’s heating PVC, which means cancer for your yet-unborn great-grandchildren. How it both kills you while still allowing you to breed is beyond our comprehension. That’s how bad PVC really is.

NASA has updated their available software catalog. If you want to go to Saturn, you first have to go to Venus three times. Here’s a tool that packs batteries. You should build a router for the interplanetary Internet.

[jlbrian7] is Breaking Android over on Hackaday.io

Last week, we had a Raspberry Pi Hack Chat with [Roger Thornton], the principal hardware engineer at Raspberry Pi. We talked about the hardware that goes into the Raspberry Pi (and the new Pi Zero W), and gave away a few Pi Zero Ws to a few people on hackaday.io that had great ideas for a project. One of the winners of a free Raspberry Pi Zero W was [arsenijs] for his Raspberry Pi Project. This is a really great project that uses a Raspberry Pi and Raspberry Pi accessories. It’s pushing the envelope of what a Pi can be, and a free Raspberry Pi Zero W couldn’t have gone to a more worthy project.

What are you doing the weekend of March 31st? We’re going to New Jersey for the Vintage Computer Festival East. This is one of the better cons we go to. Maybe this year we’ll organize a trip to the pinball museum in Asbury Park.

Ask Hackaday: Helping Hands

[ProtoG] sent us in this video (also below) where he demonstrates the use of machinist’s dial-gauge indicator arms as helping hands. I’ll admit that I got so jealous that I ordered a pair. I wouldn’t say that I need more tools to hold things in place, but I certainly want them. The rapid coarse placement combined with fine adjustment looks so sweet. Using them as scope-probe holders is brilliant.

Our own helping hands, purchased for $5 from a surplus shop, have seen nearly twenty years of use now. About ten years ago, I heat-shrinked and plasti-dipped the jaws, and since then they do less damage to cable insulation. The clips kept coming loose, but that was fixed with a little epoxy. I never used the magnifying glass, and by removing it I bought some more sliding room for the jaws, which was an easy win. The base has a “non-slip” coating of Shoe-Goo that keeps it in place on the desk. Cork might be classier.

For bigger holding, there’s always the desk vise, though I’ll admit that I mostly use it for holding PCBs while soldering, and that a better solution for that particular task wouldn’t hurt. [Mike Szczys] tells me that the Stickvise seen here is a handy thing to have on the bench. It started on Hackaday.io and we still carry it in the store.

For grabbing the fiddly little things, nothing beats a pair of hemostats and a range of tweezers. Hemostats in the desk vise make a great ad hoc holder. Good sharp tweezers pay for themselves with the first removed splinter, or placing SMT parts.

So, Hackaday, what do you use for holding things? What do you hold your PCBs with while soldering? What do you use to hold down SMD parts? What’s your third hand, or twenty-third? Continue reading “Ask Hackaday: Helping Hands”

Linux-Fu: Keeping Things Running

If you’ve used Linux from the early days (or, like me, started with Unix), you didn’t have to learn as much right away and as things have become more complex, you can kind of pick things up as you go. If you are only starting with Linux because you are using a Raspberry Pi, became unhappy with XP being orphaned, or you are running a cloud server for your latest Skynet-like IoT project, it can be daunting to pick it all up in one place.

Recently my son asked me how do you make something run on a Linux box even after you log off. I thought that was a pretty good question and not necessarily a simple answer, depending on what you want to accomplish.

There’s really four different cases I could think of:

  1. You want to launch something you know will take a long time.
  2. You run something, realize it is going to take a long time, and want to log off without stopping it.
  3. You want to write a script or other kind of program that detaches itself and keeps running (known as a daemon).
  4. You want some program to run all the time, even if you didn’t log in after a reboot.

Continue reading “Linux-Fu: Keeping Things Running”

Retrotechtacular: The Last Main Line

If you were to nominate a technology from the 19th century that most defined it and which had the greatest effect in shaping it, you might well settle upon the railway. Over the century what had started as horse-drawn mining tramways evolved into a global network of high-speed transport that meant travel times to almost anywhere in the world on land shrank from months or weeks to days or hours.

For Brits, by the end of the century a comprehensive network connected almost all but the very smallest towns and villages. There had been many railway companies formed over the years to build railways of all sizes, but these had largely conglomerated into a series of competing companies with a regional focus. Each one had its own main line, all of which radiated out from London to the regions like the spokes of a wheel.

A Ruston steam navvy excavating near Wembley, London. S.W.A.Newton/Leicestershire County Council (Fair use)
A Ruston steam navvy excavating near Wembley, London. S.W.A.Newton/Leicestershire County Council (Fair use)

By the 1890s there was only one large and ambitious railway company left that had not built a London main line. The Great Central Railway’s heartlands lay in the North Midlands and the North of England, yet had never extended southwards. In the 1890s they launched their ambitious scheme to build  their London connection, an entirely new line from their existing Nottingham station to a new terminus at Marylebone, in London.

Since this was the last of the great British main lines, and built many decades after its rivals, it saw the benefit of the century’s technological advancement. Gone were the thousands of navvies (construction workers, from “Navigational”) digging and moving soil and rock by hand, and in their place the excavation was performed using the latest steam shovels. The latest standards were used in its design, too, with shallow curves and gradients, no level crossings, and a wider Continental loading gauge in anticipation of a future channel tunnel to France This was a high-speed railway built sixty years before modern high-speed trains, and nearly ninety years before the Channel Tunnel was opened.

Continue reading “Retrotechtacular: The Last Main Line”

WTF Are Ground Loops?

These magical creatures crop up out of nowhere and fry your electronics or annoy your ear holes. Understanding them will doubtless save you money and hassle. The ground loop in a nutshell is what happens when two separate devices (A and B) are connected to ground separately, and then also connected to each other through some kind of communication cable with a ground, creating a loop. This provides two separate paths to ground (B can go through its own connection to ground or it can go through the ground of the cable to A and then to A’s ground), and means that current may start flowing in unanticipated ways. This is particularly noticeable in analog AV setups, where the result is audio hum or visible bars in a picture, but is also sometimes the cause of unexplained equipment failures. Continue reading “WTF Are Ground Loops?”

Don’t Fear The Filter: Lowpass Edition

There comes a time in every electronic designer’s life when, whether they know it or not, they need an analog filter in their design. If you’re coming from a digital background, where everything is nice and numeric, the harsh reality of continuous voltages can be a bit of a shock. But if you’re taking input from, or sending output to the big analog world out there, it pays to at least think about the frequency-domain properties of the signal, and maybe even do something about them.

Designing an analog filter to fit your needs can be a bit of a daunting task: there are many factors that you’re going to need to consider, and they all interact. It’s easy to get lost. We’re going to simplify this as much as possible by instead focusing on a few common applications and building up the simplest possible filters that work well for them.

Today, we’re going to consider the lowpass filter, and specifically a Sallen-Key filter with Butterworth characteristics and a second-order rolloff. Sound like word salad? We’ll fix that up right away, because this is probably the single most important filter to have in your analog toolbox for two very common use cases: pulse-width modulated (PWM) output and analog-to-digital conversion (ADC) input.

Continue reading “Don’t Fear The Filter: Lowpass Edition”

Friday Hack Chat: Mechanical Manufacturing

Join [Sylvia Wu], a Senior Manufacturing Engineer at Fictiv, for this week’s Hack Chat. [Sylvia’s] work at Fictiv gives her a unique viewpoint for modern manufacturing. The company connects engineers with rapid manufacturing by taking in a design and routing it to a shop that has the tools and time to fabricate the part quickly. This means seeing the same silly mistakes over and over again, but also catching the coolest new tricks as they pass by. She also spends time tearing apart consumer products to see how they have been manufactured, adding to their arsenal of available processes, both time-tested and newfangled.

Anyone interested manufacturing needs to get in on this Hack Chat. Mark your calendar for this Friday, 3/10 at noon PST (20:00 UTC)

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Upcoming Hack Chats

On Friday March 17th the Hack Chat features chip design for oscilloscopes with engineers from Keysight.