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Hackaday Dictionary: Ultrasonic Communications

เสาร์, 04/16/2016 - 00:01

Say you’ve got a neat gadget you are building. You need to send data to it, but you want to keep it simple. You could add a WiFi interface, but that sucks up power. Bluetooth Low Energy uses less power, but it can get complicated, and it’s overkill if you are just looking to send a small amount of data. If your device has a microphone, there is another way that you might not have considered: ultrasonic communications.

The idea of using sound frequencies above the limit of human hearing has a number of advantages. Most devices already have speakers and microphones capable of sending and receiving ultrasonic signals, so there is no need for extra hardware. Ultrasonic frequencies are beyond the range of human hearing, so they won’t usually be audible. They can also be transmitted alongside standard audio, so they won’t interfere with the function of a media device.

A number of gadgets already use this type of communications. The Google Chromecast HDMI dongle can use it, overlaying an ultrasonic signal on the audio output it sends to the TV. It uses this to pair with a guest device by sending a 4-digit code over ultrasound that authorizes it to join an ad-hoc WiFi network and stream content to it. The idea is that, if the device can’t pick up the ultrasound signal, it probably wasn’t invited to the party.

We reported some time ago on an implementation of ultrasonic data using GNU Radio by [Chris]. His writeup goes into a lot of detail on how he set the system up and shows a simple demo using a laptop speaker and microphone. He used Frequency Shift Keying (FSK) to encode the data into the audio, using a base frequency of 23Khz and sending data in five byte packets.

Since then, [Chris] has expanded his system to create a bi-directional system, where two devices communicate bi-directionally using different frequencies. He also changed the modulation scheme to gaussian frequency shift keying for reliability and even added a virtual driver layer on top, so the connection can transfer TCP/IP traffic. Yup, he built an ultrasonic network connection.

His implementation underlines one of the problems with this type of data transmission, though: It is slow. The speed of the data transmission is limited by the ability of the system to transmit and receive the data, and [Chris] found that he needed to keep it slow to work with cheap microphones and speakers. Specifically, he had to keep the number of samples per symbol used by the GFSK modulation high, giving the receiver more time to spot the frequency shift for each symbol in the data stream. That’s probably because the speaker and microphone aren’t specifically designed for this sort of frequency. The system also requires a preamble before each data packet, which adds to the latency of the connection.

So ultrasonic communications may not be fast, but they are harder to intercept than WiFi or other radio frequency signals. Especially if you aren’t looking for them, which inspired hacker [Kate Murphy] to create Quietnet, a simple Python chat system that uses the PyAudio library to send ultrasonic chat messages. For extra security, the system even allows you to change the carrier frequency, which could be useful if the feds are onto you. Whether overt, covert, or just for simple hardware configuration, ultrasonic communications is something to consider playing around with and adding to your bag of hardware tricks.


Filed under: digital audio hacks, Hackaday Columns, wireless hacks

Mrs. Penny’s Driving School — Hardware Workshop in Dallas

ศุกร์, 04/15/2016 - 23:00

In case you haven’t noticed, the Hackaday community is making more of an effort to be a community AFK. We’re at VCF East this weekend, have the Hackaday World Create Day quickly approaching, Hackaday | Belgrade a few days ago, and Hackaday Toronto next week just to name a few in close proximity to this post.

As promised, or threatened, depending on which end of the stick you’re on I will be teaching an electronics class at the Dallas Makerspace every 3rd Saturday of the month. The goal of these classes is to help you overcome the barrier between a hardware idea and having that hardware in your hand. I’m not an expert in PCB design or layout, but I’ve found more ways to do it wrong than I’d probably admit too and this is my way of sharing what I’ve painfully learned through trial and error. At the time of writing this article there are still a few spots available in the first class, follow the above link for tickets.

Images of my failed hopes and dreams wonderfully captured courtesy of [Krissy Heishman]

Class 1

In our first 6 hour session we’ll take a basic, high-level idea and work our way down. For example: our first project will be an AVR development board. This is something common enough that everyone will know what it is (an Arduino is an AVR development board, just in case my mom is reading this). We won’t be making an Arduino clone part-for-part but taking the Arduino idea and making it our own custom board. Maybe we add some terminal blocks instead of DuPont headers or perhaps we want a real time clock and a slide potentiometer on the board. We can do that if we want, you can’t stop us.

So class number 1 is a crash course in Eagle schematic capture and PCB layout. Since this is only 6 hours worth of class time and we need to have boards and parts ordered when we leave we won’t be getting too complicated with our design.

Class 2

By the time we meet for our second session we should have taken delivery of our shiny new PCBs and our parts order should have long since been delivered from the distributor (Mouser is more or less an hour drive from the Dallas Makerspace, not that we’ll pick the parts up at will-call for this project, but it’s nice to have the option). We will spend the second 6 hour session assembling and testing our boards. If we need to make changes to our boards we can talk about that as a part of the design process. Depending on how long assembly takes we can brainstorm some ideas for the next round of Mrs. Penny’s Driving School classes which will continue the following 3rd Saturday of the month.


Filed under: news

Mrs. Penny’s Driving School — Hardware Workshop in Dallas

ศุกร์, 04/15/2016 - 23:00

In case you haven’t noticed, the Hackaday community is making more of an effort to be a community AFK. We’re at VCF East this weekend, have the Hackaday World Create Day quickly approaching, Hackaday | Belgrade a few days ago, and Hackaday Toronto next week just to name a few in close proximity to this post.

As promised, or threatened, depending on which end of the stick you’re on I will be teaching an electronics class at the Dallas Makerspace every 3rd Saturday of the month. The goal of these classes is to help you overcome the barrier between a hardware idea and having that hardware in your hand. I’m not an expert in PCB design or layout, but I’ve found more ways to do it wrong than I’d probably admit too and this is my way of sharing what I’ve painfully learned through trial and error. At the time of writing this article there are still a few spots available in the first class, follow the above link for tickets.

Images of my failed hopes and dreams wonderfully captured courtesy of [Krissy Heishman]

Class 1

In our first 6 hour session we’ll take a basic, high-level idea and work our way down. For example: our first project will be an AVR development board. This is something common enough that everyone will know what it is (an Arduino is an AVR development board, just in case my mom is reading this). We won’t be making an Arduino clone part-for-part but taking the Arduino idea and making it our own custom board. Maybe we add some terminal blocks instead of DuPont headers or perhaps we want a real time clock and a slide potentiometer on the board. We can do that if we want, you can’t stop us.

So class number 1 is a crash course in Eagle schematic capture and PCB layout. Since this is only 6 hours worth of class time and we need to have boards and parts ordered when we leave we won’t be getting too complicated with our design.

Class 2

By the time we meet for our second session we should have taken delivery of our shiny new PCBs and our parts order should have long since been delivered from the distributor (Mouser is more or less an hour drive from the Dallas Makerspace, not that we’ll pick the parts up at will-call for this project, but it’s nice to have the option). We will spend the second 6 hour session assembling and testing our boards. If we need to make changes to our boards we can talk about that as a part of the design process. Depending on how long assembly takes we can brainstorm some ideas for the next round of Mrs. Penny’s Driving School classes which will continue the following 3rd Saturday of the month.


Filed under: news

Flappy Bird on an… E-Cigarette?

ศุกร์, 04/15/2016 - 22:00

Okay, now we’ve seen it all. Someone put the effort in to port Flappy Bird… to run on an e-cigarette. An eVic-VTC Mini to be precise. So now, between puffs, you can play one of the most frustrating games ever.

In fact, he’s also gone and compiled it for us on GitHub. And even provided download and flashing instructions in the description of the YouTube video.

As one Reddit user points out:

“Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”

To which the creator, [Balázs Bank], responded with the download links to install it yourself. Has science gone too far?

All jokes aside, he’s also written snake for the same e-cigarette and promises his next project will be actual firmware for the device.

Speaking of weird but strangely interesting e-cigarette designs, check out this NES controller we saw hacked into an e-cig!

[Thanks for the tip Josh!]


Filed under: misc hacks

Flappy Bird on an… E-Cigarette?

ศุกร์, 04/15/2016 - 22:00

Okay, now we’ve seen it all. Someone put the effort in to port Flappy Bird… to run on an e-cigarette. An eVic-VTC Mini to be precise. So now, between puffs, you can play one of the most frustrating games ever.

In fact, he’s also gone and compiled it for us on GitHub. And even provided download and flashing instructions in the description of the YouTube video.

As one Reddit user points out:

“Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”

To which the creator, [Balázs Bank], responded with the download links to install it yourself. Has science gone too far?

All jokes aside, he’s also written snake for the same e-cigarette and promises his next project will be actual firmware for the device.

Speaking of weird but strangely interesting e-cigarette designs, check out this NES controller we saw hacked into an e-cig!

[Thanks for the tip Josh!]


Filed under: misc hacks

Measuring Parts for Accurate Reverse Engineering

ศุกร์, 04/15/2016 - 21:00
Previous headquarters of Useful Thing Inc. They made the best widget you could buy in the 80s.

Like most hackers, I’ve run into a part that looks like it might do what I want, but the only documentation came from a company so thoroughly defunct their corporate office is now a nail salon and a Subway.

So, as any hacker who’s wandered through a discount store with a spare twenty, at one point I bought a Chinese caliper. Sure it measures wrong when the battery is low, the temperature has changed, if I’ve held it in my hand too long, the moon is out, etc. but it was only twenty dollars. Either way, how do I get accurate measurements out of it? Well, half-wizardry and telling yourself educated lies.

There are two golden rules to getting accurate measurements by telling lies. It may be obvious to some, but it took me quite a bit of suffering to arrive at them.

  1. Engineers are lazy. So lazy. Most things are going to be even numbers, common fractions, and if possible standard sizes. If sheets and screws come in 2 and 3mm then you bet you’re going to see a lot of 2mm and 3mm features. Also, even though the metric world is supposedly pure, you’re still going to see more 0.25 (1/4) mm measurements than you are .333333 (1/3) mm measurements. Because some small fractions are easier to think about than decimals.
  2. Your eyes lie. If it matters, measure it to be sure.
Stupid Caliper Tricks

Using a caliper should be straightforward. After all, it’s just two parts that slide against each other and a means of measuring how far it’s travelled. Nonetheless, between three measurement surfaces and a few tricks to use each one, it’s worth looking into.

The Flat Bit and the Wedgey Bit

The caliper has two types of surfaces on its jaws — a flat portion near the readout, and a wedgey region that gets thin toward the tips. Use the flat bit when you want an average measurement, and the wedgy bit when you want a point measurement.

For example, if you want to know how big to make a hole for a screw to fit through, use the flat bit. (But if you want to measure the minor diameter of the screw — the diameter inside the threads — use the wedges.) Usually, you’ll measure diameters with the flat bit. Even after measuring, though, you’ll want to use your head. Screws are usually a bit smaller than the size written on it, so an M3 screw will read 2.95 mm on the caliper. The extra play will make it pass easily through a 3 mm hole.

If you want to measure a delicate or fragile material, you also use the flat bit. The caliper should be made out of fairly hard steel. (It gets an extra point on the hardness scale for every ten dollars you spent on it.) So if you try to measure something delicate it will damage or indent the surface. This is especially true for plastic parts. For plastic parts the wedge applies a point load and deforms the surface, throwing off your measurement.

Don’t drag your calipers across surfaces when you’re done measuring. This is a pet peeve of mine. I had a coworker who would use his 250 dollar calipers to measure the width of a circuit board, and then draaaag it off the edge. The wedge is a thin, precision, hardened surface. You’re either damaging the calipers or the thing you’re measuring. Open your calipers, then remove them.

The Caliper Has Math Functions Built In

Using the zero button you can do simple addition and subtraction. Imagine that you wanted to measure the distance between the center of two holes. You could measure the distance between the outsides of the holes and then subtract off each hole’s radius to get the center distance. Or you can use the zero function when the two holes are the same size. Measure the diameter of a hole, then click zero. Now measure the outside to outside points of the holes. That will be your center to center distance — the diameter (two radii) is automatically subtracted away. Neat!

The zero function is also useful when trying to decide if something will fit into something else. What if you want to know if a shaft will fit into a hole? You could measure one, then measure another and subtract the difference to get the clearance. With calipers? Measure the shaft, click zero, then measure the hole. The value on the screen is the clearance.

The same trick is used to check the difference between two similar measurements on different parts. Measure one, press zero, and then measure the other. I also use this feature to measure how much printer filament has been extruded with a tool I made.

A Example Application Honestly, it’s amazing my old cold-end lasted so long. This unlikely event brought to you by Cyanoacrylate Glue.

With these basics and a few tricks, we can reverse engineer a thing accurately. Our victim is the new cold-end from E3D. The cold-end on my printer broke, and I needed a new one. Since I was thoroughly in an egg-chicken situation, I hoped to get someone to print me a new one at MRRF. I told them about my plight at MRRF, and they agreed to give me one of their prototypes if I designed a sled for the Prusa i2.

I started off by figuring out just exactly which measurements I needed to take: where the case and the nozzle are in relation to the stepper motor. This positions the nozzle and gives me rough outlines of the cold-end so nothing collides into anything. The rest of the features of the cold-end and their locations are not needed. You don’t need to model the whole part — just the bits that impact the part you’re building.

Thanks RepRap Wiki! You’re my favorite hot mess of a resource.

It looks like we have a mount for a stepper motor on the back. Since all steppers are built to a standard, we can apply Rule 1 right away. A quick search shows us the pattern for a NEMA 17 motor is a square hole spacing of 3mm holes at 31mm with a 27mm hole in the middle. We haven’t even taken the calipers out yet.

Okay, so let’s get the outside dimensions of the cold end. I’m getting 43.97 and 46.44. I’m going to translate that to 44mm and 46.5 via Rule 1. Likewise, I’m getting 24.67 for the depth, so 25mm it is.

Now, some of the more experienced of you will say, but Gerrit, what about draft angles? The bottom of the part is a whole 0.75mm smaller than the top. Well, again, Rule 1, but on myself this time. It really doesn’t matter. I’m only interested in this measurement to know when the part will hit something, so the biggest dimension with do.

I’m on to your dastardly illusions, off-center hole!

Now the next thing is an application of Rule 2. It looks like the shaft is sitting right in the middle of the box, which means that the stepper pattern should be right in the middle of the box. However, with a second glance it becomes apparent that the centricity is an optical illusion caused by that offset screw in the bottom right corner. It’s an important dimension, so I’m going to measure it to be sure that it’s centered.

To start, I picked the easiest corner to measure. I can assume via Rule 1 that nothing is rotated and that the stepper pattern is going to be perfectly square with everything. Even if there was some unknown advantage to rotating a stepper hole pattern, CAD software really hates that sort of thing. If I find the offset of one hole, the rest can be determined. So I simply measure the distance from the edge to the inside of a hole, and then add one half of the hole diameter to it. If the math were harder, I could have done this using the zero-offset trick.

Last, we have to get the offset from the stepper shaft to the center of the nozzle assembly that slides into the cold end. There’s no good way to get this measurement, but by combining all the skills up till now it’s fairly easy to get a good guess. Though if forced to be honest, I would throw an error of +/-1 mm on this.

So, I’ll measure the widest point of the slot. I’ll cut that measurement in half and set my caliper to that. Then I’ll set it against the side of the slot closest to the shaft. Now I’ll mentally (or with a crayon) mark the point where the other edge of the caliper sits. That’s the center of the slot. Then I’ll use a piece of paper to draw a line from the middle of the shaft to the edge I’m measuring. Now I have one measurement! 11mm.

To get the offset from the back of the cold-end to the center of the nozzle, I can apply Rule 2. I know by the documentation for the nozzle that fits into this that it’s http://wiki.e3d-online.com/wiki/E3D-v6_Documentation going to be a hole of 16mm or bigger for it to work. So, on a hunch, I look and see if the arc is 8mm tall, making it a 16mm circle. If that’s the case then I can measure from the lowest point of the arc to the back and then just add 8mm to get the offset. It ends up being 13mm from the back. Which is, just slightly forward of the center of the assembly. Thanks Rule 2!

While we’re at it, let’s get the depth of the hole that the nozzle fits into. I didn’t mention the stick thing that comes out the back of the caliper because it usually doesn’t work, but that’s what it’s there for. A quick measurement to the mating surface gives us 12.1, or 12 mm. And there we have it.

After a bit of CAD, we have a model that for all practical purposes lets us design this part into an assembly. You can see it/download it here. After a bit more work, I used it to design the promised sled. I had some other issues with the first iteration of the design, but as far as the clearances for and locations determined by the cold-end, I had no problems at all. A few iterations later, I had a final design that works pretty well!

When I got started with this sort of stuff I would always agonize over getting the model exactly right. I would make a lot of paper drawings and keep tables of measurements. As I went on I realized that a bit of cleverness and familiarity with the tools are just as good as a 3D scanner for practical purposes, and certainly a lot quicker. I wouldn’t recommend using these tricks to do a quality inspection at your job, but to get a good model with the least agony it works pretty well. Do you all have measurement tricks to share?


Filed under: Featured, slider, tool hacks

Poor Man’s Time Domain Reflectometer

ศุกร์, 04/15/2016 - 18:01

A time domain reflectometer, or TDR, is an essential piece of test gear when working on long cables. The idea is simple: send a pulse down the cable and listen for the reflection from the far end. The catch is that pesky universal constant, the speed of light.

The reason the speed of light is an issue is that, in a traditional system, the pulse needs to be complete before the reflection. Also, time is resolution, so a 1 GHz sampling rate provides a resolution of about 10 centimeters. [Krampmeier] has a different design. He sends variable length pulses and measures the overlap between the outgoing and reflected pulses. The approach allows a much simpler design compared to the traditional method.

There is one exotic part: an ECL XOR gate. ECL is a logic family that uses transistors in their active region to achieve very fast switching rates. By using an RC low pass filter on one input of the XOR gate and driving it with a pulse, the device can generate a variety of fast pulse lengths.

[Krampmeier] submitted the design for a contest, but will provide more details after the contest is done (and there is more detail further down in the same discussion thread). In addition, others mentioned links to other resources, including a cheap TDR with a Microchip PIC (the [Krampmeier] project uses an ST ARM board) and  the obligatory video from [w2aew].

We’ve talked TDRs before, of course. We’ve even looked at a tricky case where it didn’t really help much.


Filed under: ARM, tool hacks

Weight Tracking, Wise Cracking IoT Bathroom Scale

ศุกร์, 04/15/2016 - 15:01

For those fighting the battle of the bulge, the forced discipline of fitness bands and activity tracking software might not be enough motivation. Some who are slimming down need a little gentle encouragement to help you lose weight and keep it off. If that sounds like you, then by all means avoid building this weight-tracking IoT scale with an attitude.

Then again, if you live in fear of your scale, [Jamie Bailey]’s version is easy to hate, at least when your numbers are going in the wrong direction. Centered around a second-hand Wii Balance Board talking to a Raspberry Pi via Bluetooth, the scale really only captures your weight and sends it up to InitialState for tracking and feedback. Whether the feedback is in the form of jokes at your expense is, of course, is entirely up to you; if you’d rather get gentle nudges and daily affirmations, just edit a few files. Or if your tastes run more toward “Yo momma so fat” jokes, have at it.

Bathroom scales are a good hacking target, whether it’s reverse engineering a digital scale or eavesdropping on a smart scale. This build is snarky good fun, and if nothing else, it’s good for pranking your roommate. Unless your roommate is your husband or wife, of course. That’s just – no.


Filed under: Medical hacks

A Star Tracking Telescope Mount

ศุกร์, 04/15/2016 - 12:00

[Chris] recently got his hands on an old telescope. While this small refractor with an altitude-azimuth mount is sufficient for taking a gander at big objects in our solar system, high-end telescopes can be so much cooler. Large reflecting telescopes can track the night sky for hours, and usually come with a computer interface and a GOTO button. Combine this with Stellarium, the open source sky map, and you can have an entire observatory in your back yard.

For [Chris]’ entry into the 2016 Hackaday Prize, he’s giving his old telescope an upgrade. With a Raspberry Pi, a few 3D printed adapters, and a new telescope mount to create a homebrew telescope computer.

The alt-az mount really isn’t the right tool for the astronomical job. The earth spins on a tilted axis, and if you want to hold things in the night sky still, it has to turn in two axes. An equatorial mount is much more compatible with the celestial sphere. Right now, [Chris] is looking into a German equatorial mount, a telescope that is able to track an individual star through the night sky using only a clock drive motor.

To give this telescope a brain, he’ll be using a Raspberry Pi, GPS, magnetometer, and ostensibly a real-time clock to make sure the build knows where the stars are. After that, it’s a simple matter of pointing the telescope via computer and using a Raspberry Pi camera to peer into the heavens with a very, very small image sensor.

While anyone with three or four hundred dollars could simply buy a telescope with similar features, that’s really not the point for [Chris], or for amateur astronomy. There is a long, long history of amateur astronomers building their own mirrors, lenses, and mounts. [Chris] is just continuing this very long tradition, and in the process building a great entry for the 2016 Hackaday Prize

The HackadayPrize2016 is Sponsored by:








Filed under: Raspberry Pi, The Hackaday Prize

What’s a Piezo Optomechanical Circuit?

ศุกร์, 04/15/2016 - 09:00

Ever hear of a piezo-optomechanical circuit? We hadn’t either. Let’s break it down. Piezo implies some transducer that converts motion to and from energy. Opto implies light. Mechanical implies…well, mechanics. The device, from National Institute of Standards and Technology (NIST),  converts signals among optical, acoustic and radio waves. They claim a system based on this design could move and store information in future computers.

At the heart of this circuit is an optomechanical cavity, in the form of a suspended nanoscale beam. Within the beam are a series of holes that act as mirrors for very specific photons. The photons bounce back and forth thousands of times before escaping the cavity. Simultaneously, the nanoscale beam confines phonons, that is, mechanical vibrations. The photons and phonons exchange energy. Vibrations of the beam influence the buildup of photons and the photons influence the mechanical vibrations. The strength of this mutual interaction, or coupling, is one of the largest reported for an optomechanical system.

In addition to the cavities, the device includes acoustic waveguides. By channeling phonons into the optomechanical device, the device can manipulate the motion of the nanoscale beam directly and, thus, change the properties of the light trapped in the device.  An “interdigitated transducer” (IDT), which is a type of piezoelectric transducer like the ones used in surface wave devices, allows linking radio frequency electromagnetic waves, light, and acoustic waves.

The work appeared in Nature Photonics and was also the subject of a presentation at the March 2016 meeting of the American Physical Society. We’ve covered piezo transducers before, and while we’ve seen some unusual uses, we’ve never covered anything this exotic.


Filed under: news

Quieting a Cheap LCD Projector

ศุกร์, 04/15/2016 - 06:00

There’s an old saying along the lines of “You pay peanuts, you get monkeys”. That’s true of technology, too, but a good hacker can sometimes teach an old monkey new tricks. [Heye] bought an LCD projector for $60 off AliExpress, and it turned out to be rather noisy: the air fan that sucked in air to cool the LED light source made a whooshing noise.

No surprise there, but rather than give up, he decided to see what he could do about the noise. So, he took the projector apart. After some excavation, he realized that the main source of noise was the input fan, which  was small and partly covered. That’s a recipe for noise, so he cut out the plastic grille over it and mounted a larger, quieter fan on the outside. He also designed and 3D printed an external hood for this larger fan. The result, he says, is much quieter than the original, and still keeps the LED light source fairly cool. It’s a neat hack that shows how a few hours and a bit of ingenuity can sometimes make a cheap device better.

Projector hacks are a staple here. And our favorite? Swapping out the light source for a candle.


Filed under: video hacks

3D Cocooner (3D Lattice Printer)

ศุกร์, 04/15/2016 - 03:00

Sometimes it feels like we haven’t yet tapped into all the possibilities of additive manufacturing. Festo, a company that loves to try innovative things (and not always bring them to market), just came up with something called the 3D Cocooner — essentially, a rostock style 3D printer on its side, with a UV cure feature to allow it to build up skeletal structures and lattice style shapes.

Similar to the MX3D-Metal 3D printer (which is currently on a mission to build a bridge end-to-end — by itself), this 3D printer specializes in printing structures as opposed to the more traditional layer approach. It’s called the 3D Cocooner as it is a bionic technology platform designed to “spin” complex lattices, very similar to naturally occurring structures.

The cool thing is, it’s not actually using plastic filament like most printers — it’s actually printing using string! The string is covered with a special UV resin which is then hardened into place as soon as it is expelled from the print head — making this more like a giant robot spider than a 3D printer.

https://www.festo.com/group/en/repo/assets/media/3D_Cocooner-SD.mp4

Speaking of Festo’s other crazy inventions — do you remember their robotic kangaroo?

[Thanks for the tip Fred!]


Filed under: 3d Printer hacks

Materials to Know: Medium Density Fiberboard

ศุกร์, 04/15/2016 - 00:01

MDF is the cheapest and flattest wood you can buy at local hardware stores. It’s uniform in thickness, and easy to work with. It’s no wonder that it shows up in a lot of projects. MDF stands for Medium Density Fiberboard. It’s made by pressing materials together along with some steam, typically wood, fibers and glue. This bonds the fibers very tightly. Sometimes MDF is constructed much like plywood. Thinner layers of MDF will be made. Then those layers will be laminated together under glue and steam.The laminated MDF is not as good as the monolithic kind. It tends to tear and break out along the layers, but it’s hard to tell which kind you will get.

Proper way to attatch a fastener to MDF.

MDF is great, but it has a few properties to watch for. First, MDF is very weak in bending and tension. It has a Modulus of Elasticity that’s about half of plywood. Due to its structure, short interlocking fibers bound together by glue and pressure, it doesn’t take a lot to cause a crack, and then, quickly, a break. If you’d like to test this, take a sheet of MDF, cut it with a knife, flip it over, and hit the sheet right behind your cut. Chances are the MDF will split surprisingly easily right at that point.

Because of the way MDF is constructed, fasteners tend to pull out of it easily. This means that you must always make sure a fastener that sees dynamic loads (say a bearing mount) goes through the MDF to the other side into a washer and bolt. MDF also tends to compress locally after a time, so even with a washer and bolt it is possible that you will see some ovaling of the holes. If you’re going to use screws, make sure they don’t experience a lot of force, also choose ones with very large threads instead of a finer pitch. Lastly, always use a pilot hole in MDF. Any particle board can split in alarming ways. For example, if you just drive a screw into MDF, it may appear to go well at first. Then it will suddenly jump back against you. This happened because the screw is compressing the fibers in front of it, causing an upward force. The only thing pressing against that force is the top layer of laminate contacting the threads. The screw then jumps out, tearing the top layer of particle board apart.

MDF fibers tend to compress over time, especially if moisture is involved. Moisture and Glue

The biggest issue with MDF is its tendency to absorb any and all moisture. Unless it is kept perfectly dry, it will expand and eventually disintegrate. MDF, can and will mold if left damp as well, so keep that in mind. Don’t use it in constructions that stay near food or animals.

This tendency to absorb moisture makes it difficult to glue MDF. If you are laminating two sheets together, the standard wood glue like Titebond will work. Look at the edge of the board and see if there is any curvature. If there is, face the concave surfaces of the two laminates together, and spread a light coating of glue (if you use too much glue, the MDF will swell). Press them together and weight the assembly until dry.

Another recommended adhesive for laminating MDF is a spray adhesive like 3M Super 7. These adhesives don’t adsorb into the material as much. Silicone or acrylic adhesives also do well, as they’re not really “wet” (though some silicones may have the curing agent pulled out of them). These are the adhesives you’ll find backing melamine trim and sheet for finishing MDF. If you want to glue the edge of the MDF it becomes harder. The edges tend to be more absorbent and may wick away the glue and swell. It is not a trustworthy joint.

Mechanical Joiners

If you are using a joint such as a biscuit joint or dowel, make sure to get the kind that expand when they come into contact with the moisture from the glue. These work fairly well in MDF constructions because both the dowel and the MDF expand when wetted. This forms a fairly good friction fit plus some glue bonding. Watch out for dowels and biscuits in edge joints again, as MDF splits very easily.

However, if you want a joint that counts with MDF, pick through-bolted joints. If you need a reliable right angle joint use a metal bracket with bolts and washers through the holes. There are other options too, but the rule of thumb is to keep the MDF in compression and as far away from tension as you can. Tab and slot joints and finger joints work well for this reason too.

Coating and Covering

If you need to paint MDF, prepare to spend a significant amount of your time fighting MDF’s tendency to absorb the paint. However, if you must, the most effective way with the least loss, is an oil based primer sprayed on in very light layers. This lets the paint dry and cure with minimal absorption. After a few layers the wood will be sealed and  a regular water based latex paint will be very effective.

One of my MDF mold masters. It works, but nowhere near as well as tooling board. You can see how oil and resin have mercilessly absorbed into it.

I’ve tried to use MDF as masters for molds before. It can work. I had a few interesting problems at first where the MDF would absorb part A of a resin mixture but not part B. This led to a mold that looked like it was curing nicely, but would stay goopy forever. I found that an application of hairspray seemed to seal the MDF enough to apply mold release effectively, but I wouldn’t guarantee any success. Also, MDF tears as it is machined. The first few pulls from the mold will have these fibers embedded in them. There’s no real way to avoid this. Tooling board is a better choice for this.

MDF and similar particulate boards are used in industry. The typical way to finish these boards are to surround them with a layer of a completely different material. In speaker construction you’ll often find MDF wrapped with carpeting, vinyl, or leather. In cabinetry and shelving MDF is usually covered in big sheets of adhesive backed melamine.

Note, there is an MDF made with an exterior glue. This one does not absorb so much moisture. It will be easier to paint, and more difficult to glue. It is more expensive though, and may not be worth the extra cost. It might be better to use a stronger, more uniform material such as Baltic Birch Plywood at that point, unless you need a specific property MDF provides.

A close up of MDF fibers By Ajdonaghy2 CC Milling

As far as machining MDF goes, there are a few options. However, before we get to those, it’s important to note that MDF is very abrasive. The fibers used are usually not clean. There may be sand and other abrasive particulates in the blend. Your tools will dull, even carbide. On top of the abrasive properties, MDF will heat your bits up a lot. Prepare to see smoke pour out of drilling operations. Since it can’t tolerate moisture, there’s no way to cool the cutting operation, and you can pretty much kiss a bit goodbye after one job. There are some higher grades of MDF called molding grade, which are a little less abrasive, and more uniform for less heat. However, it all really still applies, and again you may not make the cost savings up.

Aside from that, everything works well on it before the tool dulls. Cutting, sanding, milling, drilling, works just fine. Watch out for blowout on the exits of your cuts. A drill bit is more likely to break out the back of the hole than drill cleanly through it. This can be combated with the standard techniques, such as placing a sacrificial wood piece behind. It is also a good idea to countersink both sides of a hole in MDF, especially if joining with screws. Make sure the cosmetic side of every cut is facing up. Don’t discount hand tools when it comes to MDF, a standard cross cut saw will tear through the stuff.

MDF can be laser cut fairly well. As far as I know most MDF doesn’t have caustic glue that would damage the laser’s mirrors, but I would watch out for the exterior grade MDF. It usually chars terribly and every edge will require a wipe down with a rag.  Otherwise prepare to get black dust on every thing. It takes a laser etch well.

MDF will remain a go to for most prototyping needs. It’s flat and easy. These day’s I mostly use decent grade Baltic Birch for the things I used to get MDF for, but every now and then I’ll still dig out a piece of the stuff for a quick project. I know there’s a ton of experience with MDF out there. I’d love to know if I got something wrong. Also, the comments on the other Materials to Know have been absolutely fantastic. If you’ve got any experience to add, please do.

Title photo By Elke Wetzig CC


Filed under: Hackaday Columns

Hackaday Invades Toronto

พฤ, 04/14/2016 - 23:01

Next Wednesday, April 20th, Hackaday will invade Toronto.

[Sophi Kravitz] and [Michael Guilfoil] are heading north of the border to meet up with our friends at HacklabTO. They’ll be hosting a Bring A Hack meetup with drinks, snacks, and swag.

Since this is a Bring A Hack, attendees are encouraged to bring whatever project you’re working on and show it off, give a lightning talk, and pitch it to the community. [Sophi]’s last visit to Toronto brought some crazy hardware to the meetup, including a gaming glove for a Commodore 64, a demonstration of Ontario’s power plants, testing hamburgers for anything that is not beef with PCR, and analog synthesizers.

Since the Hackaday Prize is in full swing, this is an excellent opportunity to team up with fellow Torontonians for a great Prize entry, or just bounce a few ideas off people to see if your idea is feasible.

The meet and greet at the Hacklab is free, but we would request that you RSVP for the event. The event is also on Hackaday.io, just in case you’d like to chat with [Sophi] or other attendees.

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Filed under: cons, The Hackaday Prize

Minions Turn Your Keyboard into a Bluetooth Keyboard

พฤ, 04/14/2016 - 22:01

Evil geniuses usually have the help of some anonymous henchmen or other accomplices, but for the rest of us these resources are usually out of reach. [Evan], on the other hand, is on his way to a helpful army of minions that will do his bidding: he recently built a USB-powered minion that turns a regular PS/2 mouse and keyboard into a Bluetooth mouse and keyboard.

[Evan] found his minion at a McDonald’s and took out essentially everything inside of it, using the minion as a case for all of the interesting bits. First he scavenged a PS/2 port from an old motherboard. An Arduino Nano is wired to an HC-05 Bluetooth chip to translate the signals from the PS/2 peripherals into Bluetooth. The HC-05 chip is a cheaper alternative to most other Bluetooth chips at around $3 vs. $40 for more traditional ones. The programming here is worth mentioning: [Evan] wrote a non-interrupt based and non-blocking PS/2 library for the Arduino that he open sourced which is the real jewel of this project.

Once all the wiring and programming is done [Evan] can turn essentially any old keyboard and mouse into something that’ll work on any modern device. He also put an NFC tag into the minion’s head so that all he has to do to connect the keyboard and mouse is to swipe his tablet or phone past the minion.

If you’re looking for an interesting case for your next project, this McDonald’s Minion toy seems to be pretty popular. PS/2 keyboards are apparently still everywhere, too, despite their obsolescence due to USB. But there are lots of other ways to get more use out of those, too.


Filed under: Arduino Hacks

Most Of What You Wish You Knew About Coils Of Wire But Were Afraid To Ask

พฤ, 04/14/2016 - 21:00

If you are a novice electronic constructor, you will become familiar with common electronic components. Resistors, capacitors, transistors, diodes, LEDs, integrated circuits. These are the fodder for countless learning projects, and will light up the breadboards of many a Raspberry Pi or Arduino owner.

There is a glaring omission in that list, the inductor. True, it’s not a component with much application in simple analogue or logic circuits, and it’s also a bit more expensive than other passive components. But this omission creates a knowledge gap with respect to inductors, a tendency for their use to be thought of as something of a black art, and a trepidation surrounding their use in kits and projects.

We think this is a shame, so here follows an introduction to inductors for the inductor novice, an attempt to demystify them and encourage you to look at them afresh if you have always steered clear of them.

Inductor basics Inductor symbol. Public domain, via Wikimedia Commons.

If you consider an electrical conductor with a current flowing through it, Oersted’s Law tells us that current will create a magnetic field around the conductor. If the current flowing through the conductor changes, Lenz’s Law tells us that as it causes the magnetic field to change, that in turn induces a current in the conductor which opposes the current flowing into it. This property is referred to as the inductance.

Inductance is measured in Henries, best described in a straight cut-and-paste from the encyclopedia that you have no requirement to memorise: “The inductance of an electric circuit is one henry when an electric current that is changing at one ampere per second results in an electromotive force of one volt across the inductor“. In practice a henry is a rather large unit, so it is more likely that you will encounter millihenries, microhenries, or even nanohenries.

Of course, a single conductor, or piece of wire, doesn’t have much ability to create magnetic field, so doesn’t have much inductance. You can increase the inductance by increasing the length of the conductor, but since you will soon run out of space for very long pieces of wire it is normal for all but the tiniest inductors to have that long length of wire wound in a coil, and round a core made from a material with a higher magnetic permeability than air. Thus the schematic symbol for an inductor is a representation of a coil of wire.

So we’ve dealt with what an inductor is. How about what it does? Where will you use one, and how will it be used?

If you are an electronic experimenter or constructor you are most likely to encounter an inductor in a DC filter, a buck/boost inverter, as a transformer, or if radio is your thing, in a tuned circuit or RF filter. They are not restricted to this selection, but considering these cases should serve to demystify  inductors and encourage you to give them another look.

Inductors as DC filters Filter inductors in an ATX PSU

Have you ever opened up a switching power supply, perhaps an ATX model from a PC? Of course you have, you’re a Hackaday reader! If you examined the components, you’ll have noticed a bunch of inductors with coils of thick enamel-covered copper wire next to where the DC cables emerge to power your computer. These serve alongside the smoothing capacitors as a filter, to remove the high frequencies and leave only the DC in the PSU output.

If you remember the paragraph earlier in which we mentioned that a rapidly changing current causes a changing magnetic field which in turn induces an opposing current you may begin to understand the theory of how these filters work: those induced opposing high frequency currents cancel out the input currents responsible for them, meanwhile the stable DC component causes no change in magnetic field and thus no reverse current and passes through unopposed.

Buck and boost inverters Boost converter basic circuit. Public domain, via Wikimedia Commons

Buck and boost inverters by comparison use the inductor’s ability to store energy as a magnetic field to efficiently convert DC power from one voltage to another. If you pass a current through an inductor you are storing energy in the magnetic field you have created around it, when you stop the current that field collapses and releases its energy by inducing a reverse current in the inductor. This process happens very rapidly so a significant amount of energy can be released in a very short time as a very high voltage spike. Sometimes this spike is a nuisance, for example relay drivers incorporate a diode to safely conduct it away from their transistors, but in a boost converter the inductor is repeatedly pulsed with energy and the resulting spikes diverted through a diode into a reservoir capacitor from which a higher output voltage can be derived.

Buck converter basic circuit. Cyril Buttay, GFDL, via Wikimedia Commons

A buck converter by comparison uses the stored energy in an inductor to release a pulse of higher current at lower voltage rather than the high voltage low current spike of the boost converter. The basic circuit is shown on the left, pulses of current create a changing magnetic field in the inductor that induces a reverse voltage which in turn drops the voltage on the load.

Both the example circuits for buck and boost converters shown here are simplified for illustrative purposes. In practice the switch will be replaced by a transistor driven from an oscillator whose pulse width is varied by a feedback circuit connected to the load. This can be a surprisingly simple discrete component circuit, but in both cases there are significant numbers of off-the-shelf integrated circuits designed for the job whose data sheets will provide valuable information about suitable inductor values.

Transformers

If you put a conductor in a changing magnetic field, a current will be induced in it. Lenz’s Law again. This is how dynamos and generators work, and the effect that gives us the reverse current in inductors we’ve been talking about in the last few paragraphs. So if you put one inductor within the changing magnetic field created by another inductor, a current will be induced in the first inductor by that magnetic field. You will have created a transformer, and if we refer to the first inductor as the primary and the second as the secondary the ratio of primary to secondary AC voltage is the same as the ratio between the number of turns of wire in primary and secondary. At a stroke we can change AC voltages from one level to another, and do so while maintaining complete physical isolation between primary and secondary.

Ferrite-cored high frequency transformers in an ATX PC PSU. Much smaller than their mains-frequency equivalents.

Practical transformers are built so that the magnetic fields of the two inductors are as closely coupled as possible. The two coils of wire will occupy the same former and be wound around the same core material, with the aim that all the magnetic flux they create will be contained within that core rather than wasted in the surroundings. The designers of a transformer will have to contend with losses due to induced currents in the core as well as losses due to the resistance of the wire, both producing heat, and with the possibility of the core saturating with magnetic field and the device becoming non-linear at the frequency of operation.

At lower frequencies such as those used by mains electricity the core usually takes the form of iron laminations insulated from their neighbours to reduce induced currents. As the frequency of operation rises the size of core required to avoid magnetic saturation decreases so there is a corresponding decrease in transformer size. This effect is offset by the requirement for higher performance core materials to work at higher frequencies, and for this reason you will see cores made from ferromagnetic ceramics known as ferrites in the high frequency transformers found in switch-mode power supplies or RF applications.

There is another type of transformer you may encounter, the autotransformer. Typically these are used in the inexpensive mains step-up or step-down transformers you can buy over the counter should you wish to use a European 230v appliance on the USA’s 110v, or vice versa. An autotransformer does not have separate windings, instead it has one winding with a third connection somewhere in the middle. Apply an AC voltage between the bottom of the winding and this third connection, and it will induce a voltage at the top of the windings proportional to the ratio between the number of turns up to the third connection, and the whole number of turns. Its operation is very similar to a conventional transformer, however it does not provide a physical isolation between primary and secondary and therefore does not offer isolation from a mains supply.

Inductors in RF circuits

Probably the area of most mystique about inductors surrounds their use in RF circuits. People tempted to try building a radio project balk at the idea of winding their own inductors, and the subject of their design may be responsible for most of that black art we mentioned earlier.

A high power air cored inductor in a radio transmitter. Public domain, via Wikimedia Commons.

In an RF circuit the designer is most interested in the resonant frequency of a circuit containing inductance and capacitance. In very simple terms if you connect a capacitor and an inductor in parallel and apply a pulse of current to the circuit the energy will “bounce” between magnetic field in the inductor through electric current in the connecting wires to charge stored in the capacitor and back again until resistance losses cause the energy to dissipate, and will do so at a frequency dependent on the inductance and capacitance involved.  There is a straightforward formula to calculate resonance that every radio amateur will recite parrot-fashion: “F equals one over two Pi root L C”, but happily there are numerous online resonance calculators if you would prefer to save a little effort.

There is perhaps less need than there might once have been for trepidation at RF inductor design, and in particular at the idea of winding your own inductors. Practical RF inductors in preset values are available off-the-shelf from multiple manufacturers, along with adjustable inductors with threaded ferrite cores that can be moved within the body of the inductor. These components are not as cheap as their resistor and capacitor counterparts, but they do make the RF constructor’s life significantly easier.

Go Forth And Solder

We hope that if you are an inductor novice this article will have given you a basic grounding in the subject and demystified these components for you. As always, there is no substitute for hands-on experience though, so if your curiosity has been aroused on the subject then we’d suggest you get to know the subject by building a few inductor circuits. Start with a simple buck or boost converter based around an off-the-shelf IC, and have a poke around at the voltages and waveforms involved with your oscilloscope. There is a whole world of magnetic goodness out there to be found!


Filed under: Featured, hardware, radio hacks, slider, Tech Hacks

Hoverboards are here – If You’re Crazy Enough to Try

พฤ, 04/14/2016 - 18:00

A new video has been stirring questions on the internet this week. It shows a test of the Flyboard Air, a device that is somewhere between a Back to the Future Hoverboard and Green Goblin’s glider. The video depicts pilot [Frank Zapata] taking off, flying around, and landing an a platform not much larger than a milk crate. Plenty of folks are calling the video a fake. After a few back of the napkin calculations though, we’re coming out to say we think it’s real. Details are few and far between, so much of the information in this article is educated guessing based upon the video.

Here’s our hypothesis: Flyboard Air is a jet powered platform with little or no built-in intelligence. Balance, stability and control are all handled by the pilot. A hand controller simply provides throttle to adjust altitude, take off, and land.

Let’s start with the jet powered part. During the video, [Frank] looks down at his board and the water below. Between his sneakers we can see two round openings – which look a lot like jet intakes. At the end of the video, [Frank] flies over the camera. stopping the action shows a split second where four exhaust holes are visible on the bottom of the board. These jets look quite a bit like model aircraft jet engines.

We don’t know exactly which engines [Frank] is using, but as an example, the Jet-Cat P 400 RX-G packs 88 lbs of thrust into a shell less than 6 inches in diameter, weighing less than 8 lbs. Four of those engines would provide 352 lbs of thrust. That’s plenty to lift [Frank], the board, and a few gallons of Jet-A strapped to his back.

Why no built-in intelligence? Even the smallest quadcopters have gyros, accellerometers, and PID loops keeping them upright. The problem boils down to the physics of jet engines. Active stability in a fixed pitch rotary blade system requires very fast throttle response. Quadcopters have this with their brushless motors. Turbines however, have throttle lag on the order of seconds. You can’t beat physics. Accelerating 3 or 4 pounds metal from 78,000 RPM (~70% throttle) to 98,000 RPM (~100 % throttle) takes time.

Standing on a column of uncontrolled thrust would take quite a bit of skill on the part of the pilot. As it turns out, [Frank] is one of the world’s most experienced thrust riders. His previous invention, the Flyboard uses a personal watercraft to create a column of thrust which the rider stands on. These boards have become tremendously popular at vacation spots in the last few years. There are plenty of videos on [Frank’s] YouTube channel showing the amount of control a skilled ride has over the board. Loops, spins, and other aerobatics look easy.

With that much skill under his belt, [Frank] would have no problem keeping balanced on four jet engines.

Such a skilled rider means that control wouldn’t really be needed on the board. We’re betting that the only electronics are the remote throttle control and the Engine Control Computers (ECU) needed to keep the jets running and synchronized. The two electric ducted fans on the sides of the Flyboard Air appear to be running all the time, only shutting down when [Frank] lands the board.

One final thought – taking off and landing a jet vertically is difficult. Ground effects destabilize the craft. Engines can suck in their own exhaust, stalling them. These are problems faced by the harrier jump jet and the joint strike fighter. [Frank’s ] solution is not never get too close to the ground. If you watch closely, he takes off and lands from a perforated metal platform mounted off the back of a van. The metal doesn’t reflect enough thrust to cause the Flyboard to become unstable or stall.

So is the video real? We think so. This is an amazing achievement for [Frank Zapata]. Is it practical or safe? Heck no! Nor is it cheap – those engines cost €8,845.00 each.  That said, we’d love a chance to ride the Flyboard Air – after a few hours of training on the original Flyboard of course.


Filed under: transportation hacks

3D Printed Microscope Chamber Saves Big Bucks

พฤ, 04/14/2016 - 15:00

Optical microscopy is over 400 years old, and in that time, it has come a long way. There are many variations of microscopes both in the selection of lenses, lighting, and other tricks to allow an instrument to coax out more information about a sample.

One proven way to increase the resolving power of a microscope is oil immersion. The sample and the lens are placed in oil that is transparent and has a high refractive index. This prevents light from refracting at the air-coverslip interface, improving the microscope’s overall performance.

The University of New South Wales has a lab that uses such a microscope. They use a special (and expensive) chamber to hold down the glass coverslip and contain the oil. The problem? At nearly $400 a pop, the chambers are a constant expense to replace, and they are not flexible enough to handle custom size requirements.

[Ben Goodnow], a first year student at the university, applied his 3D printing and laser cutting know-how to design and build a suitable chamber that costs much less and can be adapted to different projects. In addition to all the design files on GitHub, there’s also a document (PDF) that describes the design iterations and the total cost savings.

The main body uses ABS plastic, and the laser cutter produces silicone gaskets. Rare earth magnets keep the whole assembly together.

We predict a bright future for [Ben]. While you might not need an oil immersion microscope chamber, the process he followed, and the justification data he gathered are a good model for anyone who wants to justify the cost of a 3D printer and laser cutter to a boss (or, perhaps, a spouse).

Most of the microscopy on Hackaday is either aimed at SMD soldering or exotic non-optical instruments. If you want to see a comparison of oil immersion versus dry microscopy, [Bill Porter] has a video that shows the difference, below.


Filed under: 3d Printer hacks

CarontePass: Open Access Control For Your Hackerspace

พฤ, 04/14/2016 - 12:01

A problem faced by all collaborative working spaces as they grow is that of access control. How can you give your membership secure access to the space without the cost and inconvenience of having a keyholder on site at all times.

[Torehc] is working on solving this problem with his CarontePass RFID access system, at the Kreitek Makerspace (Spanish, Google Translate link) in Tenerife, Canary Islands.

Each door has a client with RFID readers, either a Raspberry Pi or an ESP8266, which  connects via WiFi to a Raspberry Pi 2 server running a Django-based REST API. This server has access to a database of paid-up members and their RFID keys, so can issue the command to the client to unlock the door. The system also supports the Telegram messaging service, and so can be queried as to whether the space is open and how many members are in at a particular time.

All the project’s resources are available on its GitHub repository, and there is a project blog (Spanish, Google Translate link) with more details.

This is a project that is still in active development, and [Torehc] admits that its security needs more work so is busy implementing HTTPS and better access security. As far as we can see through the fog of machine translation at the moment it relies on the security of its own encrypted WiFi network, so we’d be inclined to agree with him.

This isn’t the first hackerspace access system we’ve featured here. The MakerBarn in Texas has one using the Particle Photon, while the Lansing Makers Network in Michigan have an ingenious mechanism for their door, and the Nesit hackerspace in Connecticut has a very fancy system with video feedback. How does your space solve this problem?

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Filed under: Hackerspaces, security hacks, The Hackaday Prize, wireless hacks

Bacon Beacon

พฤ, 04/14/2016 - 09:00

The device featured here is quite simple, but it’s well executed and involves bacon, so what’s not to like!

They take their bacon sandwiches seriously in Dundee. And let us tell you, in Scotland they make good bacon! At the co-working space where [Grant Richmond] works, people were missing out on the chance to order when someone went to the bacon sandwich emporium for a refill.

His solution was the Bacon Beacon, a nicely lasercut box with a series of buttons on top connected to a Particle Photon microcontroller. Press a button, and a node.js web app is called on a server, which in turn sends notifications to the “Fleeple”, the inhabitants of the Fleet Collective co-working space. They can then reply with the details of their order, such as their desired sauce.

The work of sending the notifications is done through Pushbullet, but the code for [Grant]’s side of things can all be found on his GitHub repository. The whole thing was put together in Dundee MakerSpace.

We have something of an affinity for bacon and cured meat products here at Hackaday, we’ve featured more than one bacon-related exploit. The Rabbit Hole hackerspace’s “Push button, receive bacon” cooking system using a laser printer fusing roller for example, an alarm clock that cooks your tasty treat, or a full cooked breakfast using workshop tools.

Please keep them coming, and resolve to make space for a bacon-related hack this year. We promise, it won’t be one of your rasher decisions.


Filed under: cooking hacks