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Hardware hacking how-tos

Vacuum Molding With Kitchen Materials

December 26, 2017 by 14 Comments

Vacuum pumps are powerful tools because the atmospheric pressure on our planet’s surface is strong. That pressure is enough to crush evacuated vessels with impressive implosive force. At less extreme pressure differences, [hopsenrobsen] shows us how to cleverly use kitchen materials for vacuum molding fiberglass parts in a video can be seen after the break. The same technique will also work for carbon fiber molding.

We’ve seen these techniques used with commercially available vacuum bags and a wet/dry vac but in the video, we see how to make an ordinary trash bag into a container capable of forming a professional looking longboard battery cover. If the garbage bag isn’t enough of a hack, a ball of steel wool is used to keep the bag from interfering with the air hose. Some of us keep these common kitchen materials in the same cabinet so gathering them should ’t be a problem.

Epoxy should be mixed according to the directions and even though it wasn’t shown in the video, some epoxies necessitate a respirator. If you’re not sure, wear one. Lungs are important.

Fiberglass parts are not just functional, they can be beautiful. If plastic is your jam, vacuums form those parts as well. If you came simply for vacuums, how about MATLAB on a Roomba?

Thank you [Jim] who gave us this tip in the comments section about an electric longboard.

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Joule Thief Steals In Favor Of Christmas

December 22, 2017 by 14 Comments

A lot of things tend to get stretched during the holiday season, like shopping budgets and waistbands and patience. This year, [Chris] is stretching the limits of both the mini breadboard and the humble 1.5 V LR44 coin cell with his joule thief-driven LED mini Christmas tree.

With the push of a micro momentary, the joule thief circuit squeezes enough power from an LR44 to boot an MSP430 microcontroller, which needs 1.8 V – 3.6 V. After boot, the micro takes control of the joule thief circuit and milks it whenever the voltage falls below 3.2 V. This tree may be small in stature, but it’s feature-rich. A push of the same momentary button cycles through four different light shows, ending with a medley of all four. Be dazzled after the break.

The code for this tiny tree, which features an awesome ASCII breadboard layout and schematic, is up on GitHub. [Chris] has it listed among a few other manageable bare-metal ‘430 projects that would be great for beginners at pure C. If that sounds like you, why not give yourself the gift of learning a new language?

We’ve seen some spirited ways of lighting LEDs, but doing it with candle power takes the fruitcake.

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The Smartest Air Freshener In The Room

December 16, 2017 by 6 Comments

Many automatic air fresheners are wasteful in that they either ceaselessly spritz the room, and manual ones need to be — well — manually operated. This will not do in an era of smart products, so Instructables user [IgorF2] has put together an air freshener that does more than check if you’re around before freshening things up.

The air freshener uses a NodeMCU LoLin and an MG 995 servomotor, with a NeoPixel ring acting as a status light. Be aware — when the servo is triggered there is a significant spike in current, so be sure you aren’t powering the air freshener from a PC USB port or another device. After modeling the air freshener’s case in Fusion 360 — files available here — [IgorF2] wired the components together and mounted them inside the 3D printed case.

Hardware work completed, [IgorF2] has detailed how to set up the Arduino IDE and ESP8266 support for a first-time-user, as well as adding a few libraries to his sketch. A combination of an Adafruit.IO feed and ITTT — once again, showing the setup steps — handles how the air freshener operates: location detection, time specific spritzing, and after tapping a software button on your phone for those particularly lazy moments.

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Give Workshop Pencils A Flush-Mounted Home

December 15, 2017 by 17 Comments

Pencils and pens are apt to go wandering in a busy workshop if they don’t have a handy storage spot. For most of us a soup can or an old coffee mug does the trick, but for a prettier and more useful holder [Stuff I Made] has a short video demonstrating a storage unit made from an elbow fitting and a scrap piece of plywood. He cuts a plywood disk that is friction-fit into one end of the elbow, then it gets screwed into a wall making an attractively flush-mounted holder in a convenient spot.

With the right joint the bottom of the holder remains accessible, as a 90 degree bend would be no good. With a shallower joint angle, a regular screwdriver can still reach the mounting screw and it’s possible to access the bottom of the holder just in case it needs cleaning or something small falls inside. You can see the process and results in the video embedded below. Not bad for one screw, a spare joint, and a scrap piece of plywood.

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Using Gmail With OAUTH2 In Linux And On An ESP8266

December 14, 2017 by 21 Comments

One of the tasks I dread is configuring a web server to send email correctly via Gmail. The simplest way of sending emails is SMTP, and there are a number of scripts out there that provide a simple method to send mail that way with a minimum of configuration. There’s even PHP mail(), although it’s less than reliable.

Out of the box, Gmail requires OAUTH2 for authentication and to share user data, which has the major advantage of not requiring that you store your username and password in the application that requires access to your account. While they have an ‘allow less secure apps’ option that allows SMTP access for legacy products like Microsoft Outlook, it just doesn’t seem like the right way forward. Google documents how to interact with their API with OAUTH2, so why not just use that instead of putting my username and password in plaintext in a bunch of prototypes and test scripts?

Those are the thoughts that run through my head every time this comes up for a project, and each time I’ve somehow forgotten the steps to do it, also forgotten to write it down, and end up wasting quite a bit of time due to my own foolishness. As penance, I’ve decided to document the process and share it with all of you, and then also make it work on an ESP8266 board running the Arduino development environment.

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Statistics And Hacking: A Stout Little Distribution

December 13, 2017 by 18 Comments

Previously, we discussed how to apply the most basic hypothesis test: the z-test. It requires a relatively large sample size, and might be appreciated less by hackers searching for truth on a tight budget of time and money.

As an alternative, we briefly mentioned the t-test. The basic procedure still applies: form hypotheses, sample data, check your assumptions, and perform the test. This time though, we’ll run the test with real data from IoT sensors, and programmatically rather than by hand.

The most important difference between the z-test and the t-test is that the t-test uses a different probability distribution. It is called the ‘t-distribution’, and is similar in principle to the normal distribution used by the z-test, but was developed by studying the properties of small sample sizes. The precise shape of the distribution depends on your sample size. Continue reading “Statistics And Hacking: A Stout Little Distribution” →

Car Lights For Reflow Heat Source

December 12, 2017 by 26 Comments

If you only have a car and you need to unsolder some tricky surface mount components: what would you do? If you’re Kasyan TV, you’d remove your car’s halogen lights and get to town. That’s right: car lights for reflow.

When the friend of the host of Kasyan TV needed to remove some roasted toasted FETs from his motherboard but didn’t have anything for reflowing, she took some headlights and used them as an infrared source to desolder the FETs. Powered by a lab supply (although car batteries work too), the process works with 60 and 100-watt bulbs.

Now, reflowing with halogen bulbs isn’t new, and we’ve seen it done with the run of the mill 100-watt bulbs and a halogen floodlight. However, what we really like about using car lights is that they’re available everywhere and we already own some that we could (temporarily) repurpose. Now, don’t get us wrong – if you’re going to be reflowing more than just a little, there are plenty of alternative methods that don’t involve staring at “rather bright lights” for extended periods of time.

People ’round these parts can’t seem to get enough of reflow: from open source reflow oven controllers to reflowing with a hair straightener we’ve seen quite a bit. If you’re new to the reflow arena, we’ve got zero to hero: reflow style just for you. And if DIY at home reflow isn’t intense enough for you, we’ve got next level reflowing as well.

The full video is after the break, complete with Kasyan TV’s sponsored segment in the middle..

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