Listening To Mains Power

There’s a lot you can tell by looking at the waveform of your mains power. There are harmonics, transient changes, and periodic fluctuations that are correlated to the demand on the grid itself. Frequency shifts will tell you how fast or slow your clocks are running, and someone probably has a poorly isolated power line communication thing somewhere in your neighborhood. There’s a lot you can learn by looking at the waveform coming out of your outlets, but how do you tap into that? [David] is doing it with a PC sound card and some really interesting hardware.

The Grid 2 Audio module is [David]’s entry to this year’s Hackaday Prize, and it consists of three main parts. The first is the mechanical part of the design. This comes in the form of an IEC power socket with a built-in switch, fuse, and illumination. Of course, you could simply buy one of these, but [David] is teaching himself Autodesk Inventor, and you have to start somewhere. The second part of this build is the PCB power supply and mains input. This is basically a pair of transformers, a PCB, and a whole lot of isolation to make this a safe board. The third part is a signal conditioning board that sends the waveform to a 3.5mm jack, for easy processing with any audio capture hardware.

The hardest part of this board is, by far, the PCB design, and for that [David] went all out. There are some big, meaty traces on this thing and real separation between the high voltage and low voltage portions of the board. The end result is something that sends the mains waveform to an audio card for easy processing with MATLAB, and all the goodies that come from that.

Circuit VR: Measuring With LTSpice

Usually, with Circuit VR we look at some circuit in detail with simulation — usually LTSpice. This one will be a little meta because I wanted to look at a capability in LTSpice which ironically is very useful, but not often used. Along the way, though, we’ll look at why you get maximum power transfer when your source impedance matches your load impedance. This is something you probably already know about, but it is interesting to look at in simulation if you know how to coax LTSpice — no pun intended — into showing you a meaningful graph.

The circuit is super simple. An AC source and a 50-ohm resistor stand-in for a 40-meter ham transmitter. With 100 volts into a 50-ohm load. So far, so good.

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Call For Proposals: Hackaday Superconference

It’s time to submit your proposal for a talk or workshop at the 2018 Hackaday Superconference!

Yep, it’s easy to procrastinate with the late days of summer upon us, but don’t miss out on your chance to present at the Ultimate Hardware Conference. We’re hungry for great stories about hardware creation. Before you have the chance to ask “should I submit a proposal?” — YES! We’re talking to you!

Some of the general topics that have been really popular in the past include:

  • Hardware custom built for research labs
  • Clever methods for prototyping
  • Engineering heroics that met a deadline, kept on budget, or just made the thing work
  • Ins and outs of product development
  • Stories of elite hacks that deserve to be shared and preserved

This is your time. Send in your proposal now and get ready to have an incredible weekend at the Hackaday Superconference!

Guardin, Guarding The Garden: Turn Raspberry Pi Into A 3rd Eye

If you are a gardener, you’ll know only too well the distress of seeing your hard work turned into a free lunch for passing herbivorous wildlife. It’s something that has evidently vexed [Jim], because he’s come up with an automated Raspberry Pi-controlled turret to seek out invading deer, and in his words: “Persuade them to munch elsewhere”.

Before you groan and sigh that here’s yet another pan and tilt camera, let us reassure you that this one is a little bit special. For a start, it rotates upon a set of slip rings rather than an untidy mess of twisted cables, so it can perfom 360 degree rotations at will, then it has a rather well-designed tilting cage for its payload. The write-up is rather functional but worth persevering with, and he’s posted a YouTube video that we’ve placed below the break.

This is a project that still has some way to go, for example just how those pesky deer are to be sent packing isn’t made entirely clear, but we think it already shows enough potential to be worthy of a second look. The slip ring mechanism in particular could find a home in many other projects.

It’s worth reminding readers that while pan and tilt mechanisms can be as impressive as this one, sometimes they are a little more basic.

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The First Vending Machine Hacked Liquor Laws: The Puss And Mew

It is fair to say that many technologies have been influenced by human vices. What you may not realize is that vending machines saw their dawn in this way, the first vending machine was created to serve booze. Specifically, it was created to serve gin, the tipple of choice of the early 18th century. it was created as a hack to get around a law that made it harder to sell alcoholic drinks. It was the first ever vending machine: the Puss and Mew.

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Marines 3D-Print Part To Repair Multi-Million Dollar Fighter

The good news: all you need to complete the repair you’re working on is one small part. The bad news: it’s only available in a larger, expensive assembly. The worst news: shipping time is forever. We’ve all been there, and it’s a hard pill to swallow for the DIYer. Seems like a good use case for 3D-printing.

Now imagine you’re a US Marine, and instead of fixing a dishwasher or TV remote, you’ve got a $123 million F-35 fighter in the shop. The part you need is a small plastic bumper for the landing gear door, but it’s only available as part of the whole door assembly, which costs $70,000 taxpayer dollars. And lead time to get it shipped from the States is measured in weeks. Can you even entertain the notion of 3D-printing a replacement? It turns out you can, and it looks like there will be more additive manufacturing to come in Corps repair depots around the world.

Details of the printed part are not forthcoming for obvious reasons, but the part was modeled in Blender and printed in PETG on what appears to be a consumer-grade printer. The part was installed after a quick approval for airworthiness, and the grounded fighter was back in service within days. It’s encouraging that this is not a one-off; other parts have been approved for flight use by the Marines, and a whole catalog of printable parts for ground vehicles is available too. This is the reality that the 3D printing fiction of Lost in Space builds upon.

And who knows? Maybe there are field-printable parts in the disposable drones the Corps is using for standoff resupply missions.

[via 3D-Printing Industry]

Memristor May Be Fake News

The fundamental passive components of electronics are the resistor, the capacitor, the inductor, and the oscillator, right? Actually, no, oscillators aren’t considered fundamental components because they aren’t linear. Resistors, capacitors, and inductors are also irreducible. That is, you can’t combine other passive components to model them unlike, say, a potentiometer. In the last few decades, though, we’ve heard of another fundamental component — the memristor. [Isaac Abraham] asserts, though, that the memristor isn’t a new fundamental component, but just an active device.

To support that premise [Isaac] builds a periodic table of devices showing how components map to changing voltages based on the time-varying property of charge. This shows that all the basic relationships are filled and that memristor actually covers a composition of passive components. This is similar in concept to [Strukov’s] diagram implying that a memristor is the fourth quadrant of a space defined by charge vs flux. However, using the properties of this periodic table [Isaac] argues against the fundamental nature of the memristor.

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