Precise Temperature Control Of A Coffee Urn

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Hackaday Alum [Nick Schulze] decided to help out a friend who needed a controller to hold water at a precise temperature. Coffee guzzling hackers of the world should rejoice, as [Nick] targeted a coffee urn as the vessel for the project. What he came up with was a couple of custom boards and a roll-your-own temperature probe which does a fantastic job of regulating the temperature of the liquid.

Needing to switch the mains going to the heating element he immediately thought of an AC chopper circuit based on a Triac. What didn’t come to mind immediately was the need to detect the zero crossing. In the image above you can see nearest the urn his high voltage board. Below that is the zero crossing detector circuit. For feedback he created his own temperature probe using a TC1047 temperature sensor. After soldering on a filtering cap and the leads he dipped it in JB Weld to make it water tight. If you’re using this for coffee may we recommend seeking out a food safe probe.

After successful testing he added a user interface and buttoned it up in the enclosure seen in the video below.

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A Coffee Machine With An Attitude

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[Armin] and his crew at BerkelaarMRT were contacted by the Museum of Communication in The Hague to see if they could build a coffee machine that was operated only by voice. It sounded like an interesting challenge, so they took on the job and came up with a very awesome interactive coffee machine.

The interactive coffee machine is based on a coffee maker made by Animo with the ability to make cappuccino, espresso, or just a straight coffee. The electronics are based on a Motorola Xoom 10″ tablet with an Electric Sheep module from Sparkfun. This, along with a custom-made PCB with optocouplers, to allow the buttons on the coffee maker to be electronically activated.

When anyone walks up to the coffee machine, a Maxbotix sonar module detects their presence and a small animated coffee cup asks what they’d like to drink. The cute little cup then prepares the drink and waits for its next human.

There’s a video of the machine in action available below. it’s in Dutch, but anyone will be able to get the jist of how the animated coffee machine operates.

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Phase One Of A Robot Coffee Maker

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A coffee machine that brews a fresh pot of joe,  automatically putting coffee in a filter, filling the coffee maker with water, brewing, dumping the grounds, and adding sugar and cream, all without any human interaction. Some may call it the fevered dream of a madman. Others may call it a vending machine. All we know is [Phil] is working on his own version of this robot par excellence.

This is only phase one of a robotic coffee machine build, but so far [Phil] has a single cup coffee maker that can fill itself with water and dump its grounds automatically.

The electronics are based on a PIC18F4550 that controls two mechanical relays that control the solenoids, one solid state relay that controls power to the coffee maker, and two stepper motor drivers that open the lid of the coffee maker and dump the filter into the wash bin.

It’s an awesome build and we look forward to the next stage of this awesome, truly homebrew build.

 

A Drip Coffee Maker For Camping

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[TE] goes camping, and on his excursion he likes to take just the bare necessities. A sleeping bag, a tent, food, but above all else, coffee. Most camping coffee makers are a percolator design, which is widely regarded as the worst way to make coffee ever. With a little bit of ingenuity, he created an improvised drip coffee maker for camping, just the thing for a nice cup of brew in the wilderness.

If you were to make your own drip coffee maker, your first inclination might be to use a funnel, put in a filter, pour in some coffee, and load it up with hot water. This was [TE]’s first design, but he quickly realized the hole in the bottom of his makeshift funnel would clog very quickly. After investigating his electronic drip coffee maker, he discovered the bottom of the basket had a series of baffles that allowed the filter to drain over its entire bottom surface. But how to replicate this in a piece of DIY equipment?

The solution came from [TE]’s wife, who pulled out an apple slicer. This allowed the filter to sit a little proud in the basket, allowing for an efficient draining of coffee. Simple, effective, and nearly impossible to break; that’s very good camping equipment.

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Making S’mores With 50,000 Volts

[Skyy] sent us a video of him cooking s’mores with an electric arc. He’s using a flyback transformer with a zero voltage switching (ZVS) driver. This produces about 50 kV, which is more than enough to toast the marshmallow.

ZVS is a technique that triggers the semiconductor switches when they have zero voltage across them. This ensures that there’s minimal heat created by the switches, since they are not interrupting any current at the time they are toggled. ZVS is also used in lighting dimmers to switch off power without creating interference.

If you’re interested in the details, there’s a great tutorial on building the driver. If you’re interested in learning how it works, check out this simulation video.

[Skyy] admits that his setup isn’t terribly safe since it uses a breadboard, which isn’t rated for the high voltages and currents. Keep in mind that these circuits could kill you. After the break, watch a marshmallow fry in a 50 kV arc.

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Preserve Your Garden Bounty With A Solar Food Drier

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The [VelaCreations] family lives off the grid, getting the electricity that they actually use from solar and wind power. When they started looking for ways to preserve the fruit and vegetables now coming into harvest the electricity consumption and cost of a food dehydrator made them balk. What they do have plenty of at this time of year is sun and heat, so they built their own solar food drier.

The frame is made of welded square tube. They mention that you will have to alter it if you don’t have welding tools, but building your own MOT welder is just one more fun project to take on. The frame has wood rails to hold the trays of food. It is enclosed with translucent polycarbonate sheets. There is a vent in the top as well as the bottom. As the heat from the sun builds inside, it flows upward, sucking fresh air in the bottom. This carries away moisture from the food and can be regulated by adjusting the size of the bottom vent.

Copper Kettle Just For The Hipster Coffee Scene

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Handmade coffee is a feature we need to write. But for now we present this copper kettle which is designed to pour out the boiling water very slowly in order to achieve the perfect cup of slow-drip java.

[CHS] made the kettle for his friend [Nate]. The entire process starts off with an arc of flat copper sheet which makes a slightly conical cylinder when curved until the two ends meet. Getting a water tight seal on this seam is imperative and it took four or five tries to reach perfection.

To get the kettle in shape [CHS] improvised a mandrel out of a thin slice of railroad track. After polishing it smooth it goes on the inside of the copper and gives him something to hammer against. We think this step is magic… It’s kind of like the old sculpting adage that you remove everything that isn’t what you’re trying to end up with. The beauty of the piece really pops out as the final curves are hammered into the work.

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