Camping For $25: Thrift Store Hacks To Keep Cozy

A hacker is somebody who’s always thinking creatively to solve problems, usually using what they have on hand. Sometimes that means using a 555 to build a CPU, and other times it means using a dead flashlight to start a fire. In the video below the break, [Kelly] shows us a series of hacks you can use while camping in the woods for a night to keep you warm, dry, and well fed!

[Kelly] started his camping trip not in the woods, but rather at a local thrift store. Instead of packing along hundreds of dollars in gear, his aim was to keep costs low. Very low. With some searching he was able to find a blanket, cooking utensils, rope, knife, tarp, and several other camp necessities for just $25.

A good campfire is a necessity of course, and [Kelly]’s full of great ways to start a fire even if all you have is a lighter with no butane or an old flashlight with dead batteries. The purpose of the video is to show how anyone can get their bush craft on even when all they have is a few dollars and a little know-how, which he generously shares. And after watching, we’re sure you’ll agree that he met his mark.

Will you raid the local second hand store before your next camping trip? After seeing this video, you just might! And while you’re there, make sure to grab the things you’ll need to make your own camping-friendly French press so you have some good coffee while you’re out camping in your… uh… Corolla?

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Dream Bigger, Predict The Future

I’d love to tell you that I’m never wrong, but I’ve been wrong a lot. Remember the Arduino? When it was brand new, I thought it was some silly collection of libraries and a drop-down menu for people who are too lazy to just type out their own #include statements. Needless to say, it launched about a million hacks and brought microcontroller programming into the mainstream. Oops.

Similarly, about fifteen years ago, I saw an educational project out of MIT’s Media Lab. It consisted of a bunch of blocks that had LCD screens on them and would interact with each other when put together. The real hook, though, was that each block had an accelerometer inside, so you could “pour water” out of one block into another, for instance.

At that time, accelerometers were expensive, even in quantities. Even one of these cubes must have cost $100 at the time, much less a whole set. Accelerometers were so expensive that I wouldn’t have thought about incorporating one into a project, much less a dozen, so I ignored them for hacker purposes. Then came the cellphone and economies of scale. Today, even in chip shortage times, they’re readily available for around $2 each, making them useful for exactly this kind of “frivolous” use.

From the Arduino experience, I learned to never underestimate the impact of what seem to me to be “small” conveniences. (And maybe more so, the value of the tremendous common effort from the community.) From the MIT accelerometer story, the moral is that some parts will get drastically cheaper in the future, so you shouldn’t necessarily exclude the cool new sensor from your design repertoire. After all, ten years ago, nobody would have thought that we’d have laser time-of-flight rangefinders for less than a hamburger.

What new components are fantastically useful, or full of potential, that might be cheap enough in the future to make them also worth looking into? Swing by Hackaday tomorrow morning and join in the conversation!

The True Cost Of Multimeters

If you are building a home shop, it is common to try to get the cheapest gear you can possibly get. However, professionals often look at TCO or total cost of ownership. Buying a cheap car, for example, can cost more in the long run compared to buying an expensive car that requires less maintenance. Most consumers will nod sagely and think of ink jet printers. That $20 printer with the $80 cartridges might not be such a deal after all. [JohnAudioTech] bought a few cheap multimeters and now has problems with each of them. Maybe that $120 meter isn’t such a bad deal, after all.

The problems he’s seen are the same ones we’ve all seen: noisy selector switches, suspect display readings, and worn off lettering. You can see the whole story in the video below.

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Simulate Climate With An Arduino

Greenhouses create an artificial climate specifically suited to the plants you want to grow. It’s done by monitoring conditions like temperature and humidity, and making changes using things like vents, fans, irrigation, and lighting fixtures to boost temperature. But how do you know when it’s time to up the humidity, or vent some of the heat building up inside? The easy way is to use the Arduino-powered Norman climate simulator from [934Virginia] which leverages data from different locations or times of year based on NOAA weather data to mimic a particular growing environment.

Norman relies on a simple input of data about the target location, working from coordinates and specified date ranges to return minimum/maximum values for temperature and humidity weather conditions. It makes extensive use of the Dusk2Dawn library, and models other atmospheric conditions using mathematical modeling methods in order to make relatively accurate estimates of the target climate. There are some simulations on the project’s Plotly page which show what this data looks like.

This data is used by [934Virginia’s] Arduino library to compare the difference between your target climate and actual sensor readings in your greenhouse. From there you can make manual changes to the environment, or if you’re luck and already have an Arduino-based greenhouse automation system the climate adjustments can be done automatically. The project is named after Norman Borlaug, a famous soil scientist and someone worth reading about.

Editor’s Note: This article has been rewritten from the original to correct factual errors. The original article incorrectly focused on replicating a climate without the use of sensors. This project does require sensors to compare actual greenhouse conditions to historic climate conditions calculated by the library. We apologize to [934Virginia] for this and thank them for writing in to point out the errors.

Images courtesy of Wikimedia Commons.

Smooth Moves From Cheap Motors

Building an electric motor isn’t hard or technically challenging, but these motors have very little in the way of control. A stepper motor is usually employed in applications that need precision, but adding this feature to a motor adds complexity and therefore cost. There is a small $3 stepper motor available, but the downside to this motor is that it’s not exactly the Cadillac of motors, nor was it intended to be. With some coaxing, though, [T-Kuhn] was able to get a lot out of this small, cheap motor.

To test out the motors, [T-Kuhn] built a small robotic arm. He began by programming his own pulse generating algorithm that mimics a sine wave in order to smooth out the movement of the motor. An Arduino isn’t fast enough to do these computations, though, so he upgraded to using the ESP32. He also was able to implement the inverse kinematics on his own. The result of all this work for a specific platform and motor type is a robotic arm that has a very low cost but delivers performance of much more expensive hardware.

The robot arm was built by [T-Kuhn] too, and all of the details on that build, as well as all the schematics and code, are available on the project site if you need a low-cost robot arm or a good stepper motor controller for a low cost. There are many other ways of getting the most out of other types of low-cost motors as well.

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An Electromagnet Brings Harmony To This Waving Cat

We’ve noticed waving cats in restaurants and stores for years, but even the happy bobbing of their arm didn’t really catch our attention. Maybe [Josh] had seen a couple more than we have when it occurred to him to take one apart to see how they work. They are designed to run indoors from unreliable light sources and seem to bob along forever. How do the ubiquitous maneki-neko get endless mechanical motion from one tiny solar cell?

Perhaps unsurprisingly given the prevalence and cost of these devices, the answer is quite simple. The key interaction is between a permanent magnet mounted to the end of the waving arm/pendulum and a many-turn wire coil attached to the body. As the magnet swings over the coil, its movement induces a voltage. A small blob of analog circuitry reacts by running current through the coil. The end effect is that it “senses” the magnet passing by and gives it a little push to keep things moving. As long as there is light the circuit can keep pushing and the pendulum swings forever. If it happens to stop a jolt from the coil starts the pendulum swinging and the rest of the circuit takes over again. [Josh] points to a similar circuit with a very nice write up in an issue of Nuts and Volts for more detail.

We’ve covered [Josh]’s toy teardowns before and always find this category of device particularly interesting. Toys and gadgets like the maneki-neko are often governed by razor-thin profit margins and as such must satisfy an extremely challenging intersection of product constraints, combining simple design and fabrication with just enough reliability to not be a complete disappointment.

For more, watch [Josh] describe his method in person after the break, or try flashing his code to an Arduino and make a waving cat of your own.

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Cloverleaf Satellite Antenna Mounted on a Pole

Tracking CubeSats For $25

CubeSats are tiny satellites which tag along as secondary payloads during launches. They have to weigh in at under 1.33 kg, and are often built at low cost. There’s even open source designs for these little spacecrafts. Over 800 CubeSats have been launched over the last few years, with many more launches scheduled in the near future.

[Thomas Cholakov] coupled a homemade cloverleaf antenna to a software-defined radio to track some of these satellites. The antenna is built out of copper-clad wire cut to the correct length to receive 437 MHz signals. Four loops are connected together and terminated to an RF connector.

This homebrew antenna is connected into a RTL-SDR dongle. The dongle picks up the beacon signals sent by the satellites and provides the data to a PC. Due to the motion of the satellites, their beacons can be easily identified by the Doppler shift of the frequency.

[Thomas] uses SDR Console to receive data from the satellites. While the demo only shows basic receiving, much more information on decoding these satellites can be found on the SDR Satellites website.

This looks like a fun weekend project, and probably the cheapest aerospace related project possible. After the break, watch the full video explaining how to build and set up the antenna and dongle.

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