Simulate PIC And Arduino/AVR Designs With No Cloud

August 22, 2018 by Al Williams 17 Comments

I’ve always appreciated simulation tools. Sure, there’s no substitute for actually building a circuit but it sure is handy if you can fix a lot of easy problems before you start soldering and making PCBs. I’ve done quite a few posts on LTSpice and I’m also a big fan of the Falstad simulator in the browser. However, both of those don’t do a lot for you if a microcontroller is a major part of your design. I recently found an open source project called Simulide that has a few issues but does a credible job of mixed simulation. It allows you to simulate analog circuits, LCDs, stepper and servo motors and can include programmable PIC or AVR (including Arduino) processors in your simulation.

The software is available for Windows or Linux and the AVR/Arduino emulation is built in. For the PIC on Linux, you need an external software simulator that you can easily install. This is provided with the Windows version. You can see one of several videos available about an older release of the tool below. There is also a window that can compile your Arduino code and even debug it, although that almost always crashed for me after a few minutes of working. As you can see in the image above, though, it is capable of running some pretty serious Arduino code as long as you aren’t debugging.

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Measure Resistance The Colourful Way

August 22, 2018 by Jenny List 30 Comments

One of the first things anyone with an interest in electronics learns is the resistor colour code. The colour of the first band reveals the first figure, the second the subsequent figure, and the third a power-of-ten multiplier. At first you learn these colours, but eventually you just recognise the values through familiarity. You don’t have to think about multipliers when you see orange-orange-red, you just know that it’s a 3K3 resistor.

[Plusea] has come up with an entertaining interface for an ohmmeter, which instead of displaying the resistance on an LCD or a meter shows it as the colours of the code, via a set of addressable LEDs. The work is done by an ATtiny85 microcontroller, and the whole thing is mounted on a flexible PCB (fabrication of which is itself interesting, placing cut copper traces on a sheet of kapton and covering with a second kapton layer cut to be the solder mask). There is even a clever integration of a CR2032 battery holder from the PCB itself, though they admit that it could be made more compact with the use of SMD components instead of through-hole.

The write-up and associated photo album tells us a lot about the project, but is missing a crucial detail: a shot of it working. We’ll give them the benefit of the doubt on that front though, because we like the idea and its execution.

Strangely, this isn’t the first ohmmeter to use the resistor colour code in this way, we’ve previously brought you one featuring a light-up giant resistor.

Hardware Store White Balance Reference

August 21, 2018 by Tom Nardi 23 Comments

We live in a time in which taking pictures is preposterously easy: take out your phone (assuming it wasn’t already in your hands), point it at something, and tap the screen. The camera hardware and software in even basic smartphones today is good enough that you don’t need to give it much more thought than that to get decent pictures. But what if you want to do better than just decent?

Ideally you’d take photos lit by high temperature lights, but failing that, you might need to compensate by adjusting the white balance during post-processing. But to accurately adjust white balance you need a pure white reference point in the image. Thanks to some diligent research by the folks at the FastRawViewer blog, we now have a cheap and widely available source for a pure white reference material: PTFE pipe tape.

Alright, we know what you’re thinking: how hard could it be to find a white object? Well, if you’re talking about really white, it can actually be quite difficult. Take a walk down the paint aisle of your local hardware store and see just how many “whites” there actually are. Think the shirt your subject is wearing is really white? Think you can use the glossy white smartphone in their hand as a reference? Think again.

By taking a rubber eraser and wrapping it with a few layers of the PTFE tape, you can create a white reference that’s so cheap it’s effectively disposable. Which is good, because protecting your white reference object and keeping it clean can be a challenge in itself. But with a PTFE tape reference, you can just chuck the thing when the photo shoot is done.

Combine this cheap white reference with some of the DIY photography lighting setups we’ve covered in the past, and you’ll be well on the way to getting better images to document all your projects. Just remember to submit them to us when you’re done.

[Thanks to Keith Olson for the tip.]

Plasma Etching In A Microwave

August 21, 2018 by Brian Benchoff 10 Comments

Deep inside your smartphone are a handful of interesting miniature electromechanical devices. The accelerometer is a MEMS device, and was produced with some of the most impressive industrial processes on the planet. Sometimes, these nanoscale devices are produced with plasma etching, which sounds about as cool as it actually is. Once the domain of impossibly expensive industrial processes, you can now plasma etch materials in a microwave.

Of course, making plasma in this way is nothing new. If you cut a grape in half and plop it in a microwave, some really cool stuff happens. This is just the 6th grade science class demonstration of what a plasma is, and really it’s only a few dissociated water, oxygen, and nitrogen molecules poofing in a microwave. To do something useful with this plasma, you need a slightly more controlled environment.

The researchers behind this paper used a small flask with an evacuated atmosphere (about 300 mTorr) placed into a microwave for a few seconds. The experiments consisted of reducing graphene oxide to graphene, with the successful production of small squares of graphene bonded to PET film. Other experiments changed the optical properties of a zinc oxide film deposited onto a glass microscope slide and changing a PDMS film from being hydroscopic to hydrophobic.

While the results speak for themselves — you can use a microwave to generate plasma, and that plasma can change the properties of any exposed material — this is far from a real industrial process. That said, it’s good enough for an experiment and another neat technique in the home lab’s bag of tricks.

The Forgotten Art Of Riveted Structures

August 20, 2018 by Jenny List 60 Comments

If you are in the habit of seeking out abandoned railways, you may have stood in the shadow of more than one Victorian iron bridge. Massive in construction, these structures have proved to be extremely robust, with many of them still in excellent condition even after years of neglect.

A handsome riveted railway bridge, over the River Avon near Stratford-upon-Avon, UK.

When you examine them closely, an immediate difference emerges between them and any modern counterparts, unlike almost all similar metalwork created today they contain no welded joints. Arc welders like reliable electrical supplies were many decades away when they were constructed, so instead they are held together with hundreds of massive rivets. They would have been prefabricated in sections and transported to the site, where they would have been assembled by a riveting gang with a portable forge.

So for an audience in 2018, what is a rivet? If you’ve immediately thought of a pop rivet then it shares the function of joining two sheets of material by pulling them tightly together, but differs completely in its construction. These rivets start life as pieces of steel bar formed into pins with one end formed into a mushroom-style dome, probably in a hot drop-forging process.

A rivet is heated to red-hot, then placed through pre-aligned holes in the sheets to be joined, and its straight end is hammered to a mushroom shape to match the domed end. The rivet then cools down and contracts, putting it under tension and drawing the two sheets together very tightly. Tightly enough in fact that it can form a seal against water or high-pressure steam, as shown by iron rivets being used in the construction of ships, or high-pressure boilers. How is this possible? Let’s take a look!

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Restoring A 100 Year Old Vice To Pristine Condition

August 19, 2018 by Steven Dufresne 28 Comments

We love our vices. They hold pipes for us to saw away at, wood while we carve, and circuit boards so that we can solder on components. So we keep them in shape by cleaning and greasing them every now and then, [MakeEverything] went even further. He found a 100-year-old vice that was in very rough shape and which was going to be thrown out and did a beautiful restoration job on it.

It was actually worse than in rough shape. At some point, one of the jaws had been replaced by welding on a piece of rebar where the jaw would normally go. So he made entirely new jaws from solid brass as well as the pins to hold them firmly in place. We applaud his attention to detail. After removing all the old paint and corrosion, he painted it with a “hammered” spray paint to give it a nice hammered look. Though when he made the raised letters stand out by applying gold paint to them using an oil-based paint marker, we felt that was just showing off. The result is almost too gorgeous to use, but he assures us he will use it. You can see his process, as well as have a good look at the newly revived vice in the video below.

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Bench Power Supply Packs A Lot Into A DIN-Rail Package

August 18, 2018 by Dan Maloney 8 Comments

We’re not sure why we’ve got a thing for DIN-rail mounted projects, but we do. Perhaps it’s because we’ve seen so many cool industrial control cabinets, or maybe the forced neatness of DIN-mounted components resonates on some deep level. Whatever it is, if it’s DIN-rail mounted, chances are good that we’ll like it.

Take this DIN-mounted bench power supply, for instance. On the face of it, [TD-er]’s project is yet another bench supply built around those ubiquitous DPS switching power supply modules, the ones with the colorful displays. Simply throwing one of those in a DIN-mount enclosure isn’t much to write home about, but there’s more to this project than that. [TD-er] needed some fixed voltages in addition to the adjustable output, so a multi-voltage DC-DC converter board was included inside the case as well. The supply has 3.3, 5, and 12 volt fixed outputs along with the adjustable supply, and thanks to an enclosed Bluetooth module, the whole thing can be controlled from his phone. Plus it fits nicely in a compact work area, which is a nice feature.

We haven’t seen a lot of DIN-rail love around these pages — just this recent rotary phase converter with very tidy DIN-mounted controls. That’s a shame, we’d love to see more.