Manufacturing Your Own Single-Origin Tea

October 2, 2017 by Sean Boyce 33 Comments

It’s nice to take a break from hacking together the newest bleeding-edge technology, relax, and enjoy a beverage. It’s no surprise that hacks devoted to beer and coffee roasting are popular. We’ve also seen a few projects helping brew the perfect cup of tea, but none involving the actual production of tea. Today we’re going to take a short recess from modernity and explore this ancient tradition.

Consumption of tea is about equal to all other manufactured beverages, such as coffee and alcohol, combined. It is hands-down the most popular manufactured beverage in the world, and we thought it would be interesting to make some ourselves. Also the local tea is so bitter that it’s used to clean things, and it works alarmingly well. To each their own!

I started by driving into Vietnam’s Central Highlands, down what Google simply refers to as ‘unnamed road’, to about 11°52’59.3″N 108°33’49.5″E. I asked around until I found a street vendor that knew a farmer at the nearby tea plantation, and would sell us five kilograms of fresh tea. I carried it 330 kilometers back to the city, because I’m a sane person that does normal things.

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An Introduction To Solid State Relays

September 26, 2017 by Sean Boyce 54 Comments

When we think of relays, we tend to think of those big mechanical things that make a satisfying ‘click’ when activated. As nice as they are for relay-based computers, there are times when you don’t want to deal with noise or the unreliability of moving parts. This is where solid-state relays (SSRs) are worth considering. They switch faster, silently, without bouncing or arcing, last longer, and don’t contain a big inductor.

An SSR consists of two or three standard components packed into a module (you can even build one yourself). The first component is an optocoupler which isolates your control circuit from the mains power that you are controlling. Second, a triac, silicon controlled rectifier, or MOSFET that switches the mains power using the output from the optocoupler. Finally, there is usually (but not always) a ‘zero-crossing detection circuit’. This causes the relay to wait until the current it is controlling reaches zero before shutting off. Most SSRs will similarly wait until the mains voltage crosses zero volts before switching on.

If a mechanical relay turns on or off near the peak voltage when supplying AC, there is a sudden drop or rise in current. If you have an inductive load such as an electric motor, this can cause a large transient voltage spike when you turn off the relay, as the magnetic field surrounding the inductive load collapses. Switching a relay during a peak in the mains voltage also causes an electric arc between the relay terminals, wearing them down and contributing to the mechanical failure of the relay.

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A Thoughtful Variety Of Projects And Failures

September 24, 2017 by Brian McEvoy 1 Comment

Our friends at [The Thought Emporium] have been bringing us delightful projects but not all of them warrant a full-fledged video. What does anyone with a bevy of small but worthy projects do? They put them all together like so many mismatched LEGO blocks. Grab Bag #1 is the start of a semi-monthly video series which presents the smaller projects happening behind the scenes of [The Thought Emporium]’s usual video presentations.

Solar eclipse? There are two because the first was only enough to whet [The Thought Emporium]’s appetite. Ionic lifters? Learn about the favorite transformer around the shop and see what happens when high voltage wires get too close. TEA lasers? Use that transformer to make a legitimate laser with stuff around your house. Bismuth casting? Pet supply stores may have what you need to step up your casting game and it’s a total hack. Failures? We got them too.

We first covered ionocraft (lifters) awhile back. TEA lasers have been covered before. Casting is no stranger to hackaday but [The Thought Emporium] went outside the mold with their technique.

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The Illuminated Waterways Of The United States

September 20, 2017 by James Hobson 8 Comments

A recent convert to the ways of the laser cutter, redditor [i-made-a-thing] was in want of a project and — stumbling on some waterways maps on Etsy — launched into fabricating an illuminated map of all the waterways in the United States.

The map itself was laser-cut out of 1/4 inch plywood at his local makerspace. Thing is, smaller rivers and tributaries were too narrow at the scale [i-made-a-thing] wanted, so he ended up spending several hours in Photoshop preparing the image so larger rivers would be laser-cut — and not break off– while the rest would be etched onto the surface. After testing the process by making a few coasters, he was ready to get started on the real deal.

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Battery Management Module Hacked For Lithium-Iron Battery Bank

September 14, 2017 by Dan Maloney 37 Comments

In a departure from his usual repair and tear down fare, [Kerry Wong] has set out on a long-term project — building a whole-house battery bank. From the first look at the project, this will be one to watch.

To be fair, [Kerry] gave us a tease at this project a few months back with his DIY spot welder for battery tabs. Since then, he appears to have made a few crucial design decisions, not least of which is battery chemistry. Most battery banks designed for an inverter with enough power to run household appliances rely on lead-acid batteries, although lithium-ion has certainly made some inroads. [Kerry] is looking to run a fairly small 1000-watt inverter, and his analysis led him to lithium-iron cells. The video below shows what happens when an eBay pack of 80 32650 LiFePo4 cells meets his spot welder. But then the problem becomes one of sourcing a battery management system that’s up to the charge and discharge specs of his 4s battery pack. We won’t spoil the surprise for you, but suffice it to say that [Kerry] really lucked out that only minimal modifications were needed for his $9 off-the-shelf BMS module.

We’re looking forward to seeing where this build goes, not least because we’d like to build something similar too. For a more traditional AGM-based battery bank, check out this nicely-engineered solar-charged system.

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A Massive Adjustable Standing Desk From Scratch

September 13, 2017 by James Hobson 31 Comments

Standing at your desk all day is healthier by far than sitting, but the commercial options tend to be expensive. [drivenbyentropy] had to contend with a heater right where the desk would go, but building an adjustable office desk to accommodate it turned out — well — gorgeous.

Two 18″ heavy duty 12 V DC actuators raise and lower the desk with a 600 lbs static load capacity and 200 lbs of lifting load each. One actuator is actually slightly faster than the other, so instead of working out something fancy, [drivenbyentropy] simply extended the cable length on the faster actuator to disguise the difference.

Framed with some standard 2×4’s and sheathed with plywood, the massive four by eight foot desk has twelve ball-bearing drawer slides in the legs to add stability and smooth out height adjustments. Because of its size and having to build around the heating unit, the desk is stuck in the room since it does not easily come apart. There is, however, easy access to the two electronics compartments for troubleshooting!

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Wall fans for circulating hot ceiling air

Winter Is Coming: Keeping Heat Where It’s Needed

September 10, 2017 by Steven Dufresne 19 Comments

If your workshop has ceilings as high as [Niklas Roy]’s 3.6 meters (11.8 feet), then you’re familiar with his problem. Hot air rises, and there it usually stays until the heat is transferred outdoors. But in the winter time we need that heat indoors and down low. One solution is to install ceiling fans that blow that hot air back down. However, [Niklas] often builds tall things that would collide with those fans. And so he had to hack together some wall hugging fans which will be both high up and out of the way.

For the fans he’s using six of those ubiquitous standing fans, the ones that normally sit on a post a few feet off the ground and swivel back and forth. Discarding the posts, he mounted the fan bodies to a horizontal wooden frame with a wheel attached to one end, one that he’d made for another project. A rope around the wheel, and hanging down, makes it easy to tilt the fans. For controlling the fans, a friend had given him an old industrial controller, and opening it up, all he saw was corrosion. Cleaning it all out he installed an old Russian 3-position switch from his collection.

In the future he’d like to add a closed-loop control system that would not only turn the fans on and off but also adjusting their speed. For now, however, he reports that it works really well. Check out his page for build photos and more details.

Meanwhile, winter really is coming to these northern latitudes and so here are more hacks to prepare you. For automated shovelling snow, how about an RC controlled 3D printed snow blower. And while you’re snug and warm inside remotely controlling your snow blower, you can still be getting exercise using a DIY bicycle roller. But if you do venture outside, perhaps you’d want to zip around on a dogless dog sleigh.