Casein, Cello, Carrotinet, and Copper Oxide, Science Grab Bag

One of our favorite turnips, oops, citizen scientists [The Thought Emporium], has released his second Grab Bag video which can also be seen after the break. [The Thought Emporium] dips into a lot of different disciplines as most of us are prone to do. Maybe one of his passions will get your creative juices flowing and inspire your next project. Or maybe it will convince some clever folks to take better notes so they can share with the rest of the world.

Have you ever read a recipe and thought, “What if I did the complete opposite?” In chemistry lab books that’s frowned upon but it worked for the Reverse Crystal Garden. Casein proteins make cheese, glue, paint, and more so [The Thought Emporium] gave us a great resource for making our own and demonstrated a flexible conductive gel made from that resource. Since high school, [The Thought Emporium] has learned considerably more about acoustics and style as evidence by his updated cello. Maybe pulling old projects out of the closet and giving them the benefit of experience could revitalize some of our forgotten endeavors.

If any of these subjects whet your whistle, consider growing gorgeous metal crystals, mixing up some conductive paint or learning the magnetic cello. Remember to keep your lab journal tidy and share on Hackday.io.

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Gesture Keyboard for Universal Input

Keyboards are currently the most universally accepted computer input devices. They may be wired, wireless, or virtual, but the chances are that you’re within a few centimeters of a keyboard right now. [Federico Terzi] built a prototype from an Arduino and an accelerometer which conceptually resembles writing in Palm’s old Graffiti, though this version is performed in mid-air with a handheld instead of a little square at the bottom of an LCD screen.  He can also operate wirelessly with a Bluetooth module and battery.

The task of the Arduino is to take data from the accelerometer and feed it to the computer whenever a 12mm switch is pressed. Each letter is individually learned by his Python code and scikit-learn’s Support Vector Machine. There’s nothing holding a user back from giving single-letter commands to your favorite programs. For example, it would be possible to give a thumbs-up in meatspace when you want to upvote or covering your ears could mute the audio.

We love keyboard hacks like this mechanical macro keyboard, a minimal and elegant USB Morse key(board), and Brian Benchoff’s open love-letter to mechanical keyboards.

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Upgraded Hotel Room Coffee

The secret of cold-brew coffee is out. Department stores are selling gimmicks to make it at home or you can make it with a mason jar in good old-fashioned DIY style. This method is for the on-the-go hacker who may not have even the most spartan of equipment to brew a cold cup of Joe. Many hotel rooms are outfitted with a cheap percolating coffee machine and proprietary pods. The pods are just a sachet of filter paper with ground coffee inside.

Leave that percolating fire hazard unplugged and brew those pods overnight in a glass of water. In eight hours, you have a cup of rocket fuel. Compost the spent pod and away you go. Don’t heat your brew in the coffee maker, that’ll probably wreck it. Nuke it if you need it hot.

If coffee implements are your bag, here’s a 3D printed coffee bean grinder but be sure to read up on 3D printing and food safety. If coffee isn’t your cup of tea, how about a perfectly timed cup of tea?

Sensing Soil Moisture: You’re Doing it Wrong!

If you compulsively search online for inexpensive microcontroller add-ons, you will see soil moisture measurement kits. [aka] built a greenhouse with a host of hacked hardware including lights and automatic watering. What caught our attention among all these was Step 5 in their instructions where [aka] explains why the cheap soil sensing probes aren’t worth their weight in potting soil. Even worse, they may leave vacationers with a mistaken sense of security over their unattended plants.

The sensing stakes, which come with a small amplifier, work splendidly out of the box, but if you recall, passing current through electrodes via moisture is the recipe for electrolysis and that has a pretty profound effect on metal. [Aka] shows us the effects of electrolysis on these probes and mentions that damaged probes will cease to give useful information which could lead to overworked pumps and flooded helpless plants.

There is an easy solution. Graphite probes are inexpensive to make yourself. Simply harvest them from pencils or buy woodless pencils from the art store. Add some wires and hold them with shrink tube, and you have probes which won’t fail you or your plants.

Here’s some garden automation if this only whet your whistle, and here’s a robotic friend who takes care of the weeds for you.

Less Than Production, More than One-Offs

We build things we think are cool. Sometimes, other people agree with us and they want a copy of what we’ve built. If you’re lucky enough to have an enviable product but you’re not ready for full-scale manufacturing, you may be looking at a low-volume production run. [Eric Strebel] walks us through one such instance where he makes some custom color swatches for a show. Video after the break.

[Eric Strebel] is an industrial designer so he plays to his strengths by designing the swatch shape, jig, tool, and hangers. He hires out the painting, laser cutting, and CNC machining. This may seem like a simple statement but some of us have a hard time paying other people for things we’re capable of learning. In some cases, we just have to pay the professionals to do it correctly and keep our focus.

The mentality of small runs in this video is perfect for people who sell on Tindie or want to make more than a handful of consistently nice parts. Our own [Lewin Day] recently talked about his experience with a run of 200 mixers called gMix.

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Smart DC Tester Better than a Dummy Load

Testing DC supplies can be done in many ways, from connecting an actual load like a motor, to using a dummy load in the manner of a big resistor. [Jasper Sikken] is opening up his smart tester for everyone. He is even putting it on Tindie! Normally a supply like a battery or a generator would be given multiple tests with different loads and periodic readings. Believe us, this can be tedious. [Jasper Sikken]’s simulated load takes away the tedium and guesswork by allowing the test parameters to be adjusted and recorded over a serial interface. Of course, this can be automated.

In the video after the break, you can see an adjustment in the constant-current mode from 0mA to 1000mA. His supply, meter, and serial data all track to within one significant digit. If you are testing any kind of power generator, super-capacitor, or potato battery and want a data log, this might be your ticket.

We love testers, from a feature-rich LED tester to a lead (Pb) tester for potable water.

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Robotic Arm Rivals Industrial Counterparts

We’ve seen industrial robotic arms in real life. We’ve seen them in classrooms and factories. Before today, we’ve never mistaken a homemade robotic arm for one of the price-of-a-new-home robotic arms. Today, [Chris Annin] made us look twice when we watched the video of his six-axis robotic arm. Most of the DIY arms have a personal flare from their creator so we have to assume [Chris Annin] is either a robot himself or he intended to build a very clean-looking arm when he started.

He puts it through its paces in the video, available after the break, by starting with some stretches, weight-lifting, then following it up and a game of Jenga. After a hard day, we see the arm helping in the kitchen and even cracking open a cold one. At the ten-minute mark, [Chris Annin] walks us through the major components and talks about where to find many, many more details about the arm.

Many of the robotic arms on Hackaday are here by virtue of resourcefulness, creativity or unusual implementation but this one is here because of its similarity to the big boys.

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