Making Smoke That Really Performs

February 5, 2018 by 40 Comments

Smoke is a useful thing, whether you want to hide from enemy combatants or just make a big scene at a local sporting match. Smoke devices have lots of applications, many of which will likely cause a nuisance to somebody, somewhere. With that said, they can also be really cool, and [Tech Ingredients] is here to tell you how to make them.

Far from a simple tutorial, the video guide is loaded with detail. It begins with an explanation of the basic chemistry involved, using potassium nitrate and sugar. This is the basis of rocket candy, a popular method for making solid rocket motors at home. However, it’s then explained how the formula is altered to suit a smoke-making, rather than a thrust-making device. The trick is the addition of paraffin to moderate the reaction.

The tips don’t stop there. The guide explains how to use a coffee grinder to make the coarse ingredients finer, which increases the surface area and allows the powder constituents to blend with the wax more easily. Enclosures are also discussed, with a cardboard tube and bentonite clay favored for its heat resistance and stability.

Overall, it’s an excellent guide which takes the time to explain the rationale behind each step in the process. It’s great to see the underlying concepts explained with the practical execution, giving a strong understanding of not just how to do it, but why. Video after the break.

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Black Holes And The Elusive Mystery That Lies Within An Equation

February 5, 2018 by 83 Comments

“If I have seen further than others, it is by standing upon the shoulders of giants.” This famous quote by Isaac Newton points to an axiom that lies at the heart of The Sciences — knowledge precedes knowledge.

What we know today is entirely based upon what we learned in the past. This general pattern is echoed throughout recorded history by the revelation of one scientific mystery leading to other mysteries… other more compounding questions. In the vast majority of cases these mysteries and other questions are sprung from the source of an experiment with an unexpected outcome sparking the question: “why the hell did it do that?” This leads to more experiments which creates even more questions and next thing you know we go from moving around on horse-drawn carriages to landing drones on Mars in a few generations.

The observant of you will have noticed that I preceded a statement above with “the vast majority of cases.” Apart from particle physics, almost all scientific discovery throughout recorded history has been made via experiment and observation. There are a few, however, that have been discovered hidden within the confines of an equation, only later to be confirmed with observation. One such discovery is the Black Hole, and how it was stumbled upon on a dusty chalkboard in the early 1900s will be the focal point of today’s article.

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Making Software Defined Radio Portable

February 5, 2018 by 20 Comments

While most smartphones can receive at least some radio, transmitting radio signals is an entirely different matter. But, if you have an Android phone and a few antennas (and a ham radio license) it turns out that it is possible to get a respectable software-defined radio on your handset.

[Adrian] set this up to be fully portable as well, so he is running both the transceiver and the Android phone from a rechargeable battery bank. The transceiver is also an interesting miniaturized version of the LimeSDR, the Lime SDR Mini, a crowdfunded Open Source radio platform intended for applications where space is at a premium. It operates on the 10 MHz to 3.5 GHz bands, has two channels, and has a decent price tag too at under $100.

For someone looking for an SDR project or who needs something very portable and self-contained, this could be a great option. The code, firmware, and board layout files are all also open source, which is always a great feature. If you’re new to SDR though, there’s a classic project that will get you off the ground for even less effort.

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Repairing A Wounded Mantis

February 5, 2018 by 20 Comments

While it’s true that we didn’t specifically say making Hackaday staff exceedingly jealous of your good fortune would deduct points from your entry into our ongoing “Repairs You Can Print Contest”, we feel like [Sam Perry] really should have known better. During a recent dumpster dive he found an older, slightly damaged, but still ridiculously awesome Mantis stereo inspection microscope. Seriously, who’s throwing stuff like this away?

Rendered replacement mount in Fusion 360

Apparently, the microscope itself worked fine, and beyond some scratches and dings that accumulated over the years, the only serious issue was a completely shattered mount. Luckily he still had the pieces and could get a pretty good idea of what it was supposed to look like. After what we imagine was not an insignificant amount of time in Fusion 360, he was able to model and then print a replacement.

The replacement part was printed on a Tronxy P802M in PLA. Even at 0.3mm layer height, it still took over 10 hours to print such a large and complex component. A few standard nuts and bolts later, and he had a drop-in replacement for the original mount.

Whether it’s due to how big and heavy the Mantis is, or a slight miscalculation in his model, [Sam] does mention that the scope doesn’t sit perfectly level; he estimates it’s off by about 5 degrees.

We’re somewhat suspicious that mentioning an error of only 5 degrees is a stealth-brag on the same level as telling everyone you found a Mantis in the trash. But if [Sam] gives us the GPS coordinates of the dumpster in which people are throwing away high-end lab equipment, all will be forgiven.

There’s still plenty of time to get your entry into the “Repairs You Can Print” contest! The top twenty projects will receive $100 in Tindie store credit, and the top entries in the Student and Organization categories will each receive a Prusa i3 MK3 with the Quad Material upgrade kit: arguably one of the best 3D printers currently on the market. If you were considering going back to school, or finally leaving your basement and joining a hackerspace, now would definitely be the time.

A Game That Does More With Less

February 4, 2018 by 17 Comments

[David Johnson-Davies] created a minimal Secret Maze Game using a single ATTiny85 and a few common components. This simple game uses four buttons, four LEDs, and a small speaker. The player moves in the four cardinal directions using buttons, and the LEDs show walls and corridors. If an LED is lit, it means the path in that direction is blocked by a wall, and attempting to move in that direction will make a beep. When the player reaches the exit, a short victory tune chirps from the speaker.

Sample maze. A 16×16 matrix is allocated for maze designs.

Since the ATTiny85 has only five I/O lines, [David] had to get a bit clever to read four buttons, display output on four LEDs, and drive a little speaker. The solution was to dedicate one pin to the speaker and the other four to charlieplexing, which is a method of driving more LEDs than you have pins. It takes advantage of the fact that most microcontroller pins can easily switch state between output high, output low, or low-impedance high-impedance input.

As for the buttons, [David] charlieplexed them as well. Instead of putting an LED in a charlieplexed “cell”, the cell contains a diode and an SPST switch in series with the diode. To read the state of the switch, one I/O line is first driven low and the other I/O line is made an input with a pullup. A closed switch reads low on the input, and an open switch reads high. With charlieplexing, four pins is sufficient for up to twelve LEDs (or buttons) in any combination, which is more than enough for the Secret Maze.

Charlieplexing is also what’s behind this 110 LED micro-marquee display, or this elegant 7-segment display concept that takes advantage of modern PCB manufacturing options.

Always Misplacing Your Keys? You Can Fix That With Some Logic Chips

February 4, 2018 by 19 Comments

Every time he came home, it was the same thing. As soon as he crossed the threshold, his keys just disappeared. There was no other logical explanation for it. And whenever it was time to leave again, he had to turn the house upside down to find them.

One day, [out-of-the-box] decided he’d had enough and built a door-activated alarm system out of stuff he had on hand—a decade counter, a cheapo reed switch-based door alarm, and some transistors. When the door is closed, the decade counter’s output is set to light up a green LED. When he comes home and opens the door, the reed switch closes, triggering the decade counter to shift its output to the next pin. The red LED comes on, and NPN transistor grounds the piezo, sounding the alarm. The only way to stop it is by inserting a shorted 1/4″ phone plug conveniently attached to his key ring into a jack on the circuit board until he hears that satisfying click of safe key-ping.

For those times when immediately plugging the keys into the wall isn’t feasible, or if his keys should disappear before he has the chance, there’s a momentary on the board that will stop the symphony of robotic cicadas blasting out from the piezo. It’s also good for family members who don’t want to play along or haven’t yet earned their 1/4″ plug.

Be sure to check out the build video after the break, which is just through that door there. And keep an eye on your keys, eh? Hackaday is not responsible for lost or stolen personal articles. Should you lose them, we can only suggest making a new car key from the spare and printing replacements for any standard keys.

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Hackaday Links: February 4th, 2018

February 4, 2018 by 14 Comments

Here’s something remarkably displeasant. Can you cook a steak with glue? [Dom] and [Chris] from ExplosiveDischarge have cooked a steak using a huge, huge amount of two-part epoxy. The chemistry behind this is just the exothermic reaction when two-part epoxy kicks off, and yes, the steak (a very thin cut) was sufficiently wrapped and protected from the hot sticky goo. What were the results? An overcooked steak, actually. This isn’t a sous vide setup where the temperature ramps up to 50°C and stays there — the temperature actually hit 80°C at its peak. There are a few ways to fix this, either by getting a thicker cut of steak, adding some bizarre water cooling setup to keep the temperature plateaued at a reasonable temperature.

This is your weekly reminder for the Repairs You Can Print contest.

We’ve got a twofer for awesome remote-controlled hovering stuff. The first is a 1:8 scale Harrier. This plane designed and built by [Joel Vlashof] will be a reasonably accurate model of a Harrier, capable of VTOL. It’s built around a huge 130mm EDF, powered by 2x6s lipos, and stabilized with a kk2.1 flight controller with VTOL software. This is as accurate a Harrier that you’re going to get in such a small format, and has the cool little spinny vanes that allow the beast to transition from vertical to horizontal flight.

Want some more cool hovering things? [Tom Stanton] is building a remote controlled Chinook. Yes, that helicopter with two main rotors. The usual way of doing this is with proper helicopter control systems like collectives and Jesus nuts. [Tom]’s building this version with standard quadcopter technology, mounting a motor to a servo, and doubling it up, and mounting it on a frame. In effect, this RC Chinook is the tail boom of a tricopter doubled up on a single frame. It does fly, and he’s even built a neat foamboard body for it.

SpaceX’s Falcon Heavy is going to do something next Tuesday, sometime in the afternoon, east coast time. Whatever happens, it’s going to be spectacular.

Hey, it’s time for a poll. I need to decide between ‘tide pod’ and ‘solo jazz’. For what I’m doing, the cost and effort are the same, I just need to know which is more ａｅｓｔｈｅｔｉｃ, cool, or whatever. Right now it’s 50:50. One must be crowned victorious!

Here’s the stupidest thing you’re going to see all year. That’s someone looping a quadcopter in front of a Frontier A320 (Probably. Seems too big for a 319 and too small for a 321) on approach. This guy is 3.6 miles East of runway 25L at McCarran Internation in Las Vegas, at an altitude far above the 400-foot limit. Judging from the video and the wingspan, this quad came within 200 feet of a plane carrying at least 150 people. It’s the stupidest thing you’ve ever seen, so don’t do it. It’ll be great to see the guy responsible for this in jail.