Category Archives: EMSL Projects

A round up of our “Basics” articles

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Over the course of the past few years, we’ve been writing occasional “Basics” articles, about introductory topics in electronics and microcontrollers.  In the spirit of making things easy to find, we’ve now tagged them so that you can find them with this link, and we’re collecting them together in this index that will be updated from time to time.

Our “Basics” articles about electronics in general:

Additional “Basics” articles about working with AVR microcontrollers:

Play with your food: How to Make Sconic Sections

Sconic Sections

The conic sections are the four classic geometric curves that can occur at the intersection between a cone and a plane: the circleellipseparabola, and hyperbola.

The scone is a classic single-serving quick bread that is often served with breakfast or tea.

And, at the intersection of the two, we present something entirely new, delightfully educational, and remarkably tasty: Sconic Sections.

Sconic Sections: Circle Sconic Sections: Ellipse
Sconic Sections: Parabola Sconic Sections: Hyperbola

In what follows, we’ll show you how to bake cone-shaped scones, to slice them into plane geometric curves, and to highlight those curves by selective application of toppings.  We’ll also discuss some of the methods that didn’t work so well, as we refined our methods for making these.

Onwards, towards parabolic preserves and hyperbolic Nutella!

Continue reading Play with your food: How to Make Sconic Sections

How to Make Sweet Makrut Lime Liqueur

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Here’s how to make an exotic makrut lime based variation on Limoncello.  Limoncello is a sweet Italian liqueur made with lemon-peel infused vodka (or grain alcohol) and simple syrup.  Our variation adds a exotic twist to a fantastic summer treat.

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makrut lime leaves are one of the signature flavors of Thai food. They’re often available at asian grocery stores in small bunches, but the trees are also available at some nurseries. When they first leaf out, the young double-lobed leaves are purplish, tender, and very spicy. The flavor of makrut lime is a distinct citrus flavor, as different from lime as lemon, orange, and grapefruit are from one another. The makrut lime tree also produces fruit (wrinkly little spherical green lime), and the zest of that fruit contains the same flavor as the leaves.  However, it’s generally easier to obtain the leaves, as they are found more commonly in Thai cooking.

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As the leaves mature to green, they mellow in flavor and begin to toughen. We usually pick them when they’ve just turned bright green, but are still tender.

Making Limoncello is a straightforward (but slightly lengthy) process of adding lemon zest to vodka or other neutral strong spirits, waiting several weeks, and then adding simple syrup and waiting a bit more. Our favorite Limoncello recipe served as a starting point of this variation. We also found a forum discussing the idea of using makrut limes, which gave us a starting point in terms of the number of leaves to use.

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Step 1: Add 20 washed and dried leaves in a one-liter bottle of good quality vodka. (Our favorites are Polish or Austrian potato vodkas like Monopolowa and Luksosawa.)

A common and traditional variation is to use straight grain alcohol that allows you to use a shorter infusing period. However, following the GIGO principle, we’ve generally found that starting with a drinkable input results in a more drinkable output.

Set the bottle it in the back of a cupboard and forget about it for about a month. If you happen to see it on occasion, shake it a bit and open it to see how it smells. You’ll want to make Thai food.

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After a few weeks, the leaves will have leached their favor (and a hint of their color) into the vodka.

Step 2: Dissolve 1 3/4 cups sugar completely in 2 1/2 cups water. Microwaving it in a glass measuring cup for a couple of minutes will typically get it warm enough to dissolve.

Step 3: Thoroughly cool the simple syrup, to at least room temperature. (It’s okay to leave it in the fridge overnight.) If it is not fully cooled, it can result in an opaque final product.

Step 4: Pour the infused vodka and the simple syrup into a larger bottle (or multiple small ones), discarding the leaves.

Most variations on this kind of recipe suggest waiting a few days after making it “for it to mellow,” although you may not be able to resist trying it first.

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Cheers!

Editor’s note April 10, 2021: This article has been edited to replace the word kaffir, which is offensive, with makrut, which is the preferred name for the fruit.

Quick project: 24-hour Cosplay Sword

Cosplay Sword 1

Junior Evil Mad Scientist Chris came to us for help with what turned out to be a funny little (well, huge) cosplay prop project. The kind of project that starts off with a conversation that goes like this:

“You want to build what?”
“A giant sword for my costume for FanimeCon!”
“And when do you need it by?”
“Uh… tomorrow?”

So, we got to help make a 64″ long replica sword, one of several from the flash game Epic Battle Fantasy 3 (which we had admittedly never heard of before), in what turned out to be kind of an interesting (if quick) project.

Chris drew up the outline for the sword in Inkscape, by tracing the outline of a bitmap drawing of the sword in a larger collection (where you can find this one in the top row, one third of the way from the left).   We cut the outline on our CNC router from lightweight 3/4″ hardwood plywood— strong enough to not be floppy, yet light enough to be carried — and sanded the sides until it could be handled without creating splinters. We also sanded a slight bevel around the edges of the blade, so as to create the illusion of a sharpened edge without actually thinning it much around the edges.

Next, we needed to paint the sword silver.  We had some silver spray paint on hand (left over from our 555 Footstool project!), but if you directly spray paint lightweight plywood, it tends to soak into the wood unevenly, dry slowly, and leave a finish that awkwardly highlights the grain of the underlying wood.  Instead, we coated the sword with a fast-drying sanding sealer and allowed it to dry for two hours before getting out the spray paint.

 

Cosplay Sword 3

In the mean time, we made the hilt details— what might count as greebles —by laser cutting two sheets of thin 1/8″ thick plywood on each side, in a shape slightly inset from the outline of the thicker plywood.  There are two of these, one to go on each side of the hilt.

Cosplay Sword 2

Once the sanding sealer had dried enough to gently sand, we test-fit the parts together. The photo above shows how the parts look after laser cutting and with the slick, yellowish finish that the sanding sealer gives to the plywood.

Next, we spray painted the body of the sword. Primer gray for the hilt section and metallic silver for the blade section, and allowed it to dry overnight.

Separately, we painted the laser-cut overlays black with black one-part polyurethane finish (the same type that we used for our ASCII art Tie Fighter project), and allowed them to dry separately.

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In the morning, a little superglue attaches the newly-black hilt details, an old leather belt becomes some lashing details, with the help of a staple gun, and… it’s off to the show.

In case you’re interested, you can download a copy of Chris’s sword design here, as an Inkscape SVG file.


You can find more costume projects in our Halloween Project Archive.

Winner, Name that Ware May 2013

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Congratulations to reader VAX-Dude for winning the Name that Ware contest for May 2013, by correctly identifying our mystery ware as a VAX 9000 series High Density Signal Carrier (HDSC).

Which might lead you to ask another perfectly reasonable question: What the heck is a High Density Signal Carrier? Continue reading Winner, Name that Ware May 2013

3D printing use case: Custom parts for vintage cars

We always hear about how someday people will just print out rather than order spare parts for their cars. Here’s someone who actually does it.

When instructables user madmorrie had new door trims (interior panels) made for his 1962 Valiant, he neglected to allow for clearance for the door lock levers on the back door, so the original levers would no longer work. In the photo above you can see the end of the mounting post for the levers is flush with surface of the new panel, leaving no way to attach them.

Rather than have expensive new door trims made, he decided to make new levers. He designed the new levers with an extended splined section that could be recessed into the door trim and wrote up his experience in his instructable, Custom 3D Printed Car Parts.

It’s likely that no other 1962 Valiant owner will ever have the same problem, and that’s exactly why 3D printing is a good choice in this scenario. While 3D printing can get expensive for larger parts, when building tiny parts like these, you can save a lot of money by not paying for tooling costs.

And it turns out that 3D printing is good enough, even in low-cost materials (about $15 for the pair through Shapeways), for a usable part. Madmorrie says,

Initially I was intending to order them in stainless steel, however the plastic ones seem to be perfectly strong enough, so unless they break I will stick with them.

And, they look great!

All photos by madmorrie.

DIY Deck Ambiance with Flickering LEDs

Jack Olsen (of the awesome 12-Gauge Garage) wrote in about using our flickering LEDs to line the deck and pergola he had just built.

He says, “The LED candle effect is great, and really gives the place a relaxed feel at night.” You can read more about the deck project over at the Garage Journal forums, where he describes the build in more detail:

It has 28 real candles on it that I’ve hollowed out to accommodate flickering LED lights. It’s pretty convincing.

I have a pair of 3 v power supplies — each feeds half the light set. They’re plugged into a switched outlet with wire running down along the edge/underside of the deck and up through one of the pillars, then sneaking around the back of the wooden frieze thing and into holes drilled in the backside of the frame.

He even sent us a before shot, so you can see just how from-the-ground-up building the deck was. Thanks for sharing your project with us!

All photos by Jack Olsen.

Name that Ware May 2013

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In cooperation with Bunnie Studios, the blog of renowned hardware hacker Bunnie Huang (of Hacking the xbox and Chumby fame), we’re pleased to present an unusual “ware” that we acquired from one of our local Silicon Valley electronics surplus dealers.

(If you’re unfamiliar with the game, “Name that Ware” is a regular contest on Bunnie’s blog, where the goal is to learn about reverse engineering by analyzing unusual— or common but seldom-seen —hardware.  You can read about the contest rules here, and you can see many pictures of past entries with this google image search, or even get a calendar featuring Name that Ware entries from prior years.)

In the detail photos that follow, we’ll show some close-up photos, and provide a little more physical description (without speculating too much as to the purpose of the different features).   Can you identify this piece of hardware?

Continue reading Name that Ware May 2013

Alpha Clock Five: Introducing the Blue Edition!

Introducing our newest open source hardware kit: The Blue Edition of Alpha Clock Five.

Alpha Clock Five Red  Alpha Clock Five White

Alpha Clock Five is our flagship clock kit, which thus far has been available only in a Red Edition and in a White Edition. Whichever color you happen to like, it is a full-featured, beautiful, and extraordinarily easy-to-read desk clock based around oversized 2.3″ alphanumeric LED displays. It’s designed to work equally well as a bedside alarm clock and as a computer-controlled alphanumeric data display device.

We’ve already written extensively about the core design of Alpha Clock Five. We’ve also written about the modes and features added in version 2.0 of our Arduino-compatible firmware (such as date display and daisy chained scrolling text), and about the hardware changes necessary to support the White Edition of the kit. Fortunately, the changes that we made in order to support the White Edition also allow us to support the use of blue LEDs, just as easily. And so— by popular request —we now present the Blue Edition.

 

Here, the Blue Edition is shown with a soda can for scale. These LEDs are big and bright, and cast a heavy glow on the soda can and tabletop. (The usual caveats about the difficulty of photographing LEDs apply: A camera cannot capture the apparent intensity of pure blue LEDs in the same way that your eyes can.)

 

As with the other Alpha Clock Five kits, the control buttons are cut as flexures into the top of the laser-cut acrylic case, that can bend down to contact right-angle tactile button switches at the top edge of the circuit board. The top and bottom sides of the case are made of black acrylic, and the rear panel is made from smoke-gray acrylic.

For the Blue Edition, the front face of the case is made of deep blue transparent acrylic, which helps to increase display contrast, especially in brightly lit office environments.

Without the top and back panels, you can see the electronics within: the AVR microcontroller, LED driver chips, transistors, Chronodot RTC module and the other parts that make it all work.

 

The Blue Edition of Alpha Clock Five is available now at the Evil Mad Scientist shop.