Freeze Drying Astronaut Ice Cream

January 15, 2012 by Brian Benchoff 29 Comments

In our younger and more vulnerable years nothing was greater than visiting a museum, going to the gift shop, and badgering our parents to buy a pack of astronaut ice cream. Freeze dried ice cream leaves a taste of nostalgic chalky sweetness in our mouths, so we’re very excited to see that [Ben Krasnow] is now making his own astronaut ice cream.

The basic principle of freeze drying is simple. All you have to do is reduce the pressure and temperature of the food below the triple point of water and pump the sublimated water vapor out. For [Ben], this meant he needed to cool his Neapolitan Klondike bar to -30° C in a bath of chilled ethanol and pump out the air with a vacuum pump.

Interestingly, [Ben] found it necessary to heat his ice cream while under vacuum to extract more water vapor. This makes sense; at the pressures he was dealing with, [Ben] would never come across water in a liquid state. The entire process took about 18 hours. [Ben] admits this may have been a little longer than necessary, but it’s a small price to pay for reliving childhood memories.

Bang-banging Your Way To A Perfect Cake

January 5, 2012 by Mike Nathan 26 Comments

bang-bang-oven-control

[Rob Spanton’s] house is equipped with a rather cheap oven, which was discovered while his roommate tried using it to bake part of a wedding cake. If someone took a shower during the baking process, a large portion of unit’s gas pressure was diverted to the boiler, causing the oven to shut off completely. This is obviously not a good situation for baking cakes, so the housemates decided to construct a makeshift controller to keep temperatures in line.

They started by installing a pulley on the oven’s knob, which is connected to a small motor via a long rubber belt. The other end of the belt connects to a small motor, which is controlled by a Pololu 18v7 motor controller. A K-type thermocouple monitors the oven’s temp, feeding the data through a MAX6675 converter to (presumably) [Rob’s] computer.

Since they were in a bit of a time crunch, [Rob] and his roommate [Johannes] decided the best way to keep the oven at a steady temperature was via bang-bang control. While you might imagine that cranking the gas knob between its minimum and maximum settings repeatedly wouldn’t be the ideal way to go about things, their solution worked pretty well. The cake came out perfectly, and the maximum temperature swing throughout the entire baking process was only 11.5°C – which is pretty reasonable considering the setup.

Securing Your Keurig With RFID

January 4, 2012 by Mike Nathan 42 Comments

keurig-hacking

[Andrew Robinson] and his co-workers are lucky enough to have a Keurig coffee maker in their office, though they have a hard time keeping track of who owes what to the community coffee fund. Since K-Cups are more expensive than bulk coffee, [Andrew] decided that they needed a better way to log everyone’s drinking habits in order to know who needs to cough up the most cash at the end of the month.

He started by tearing down the Keurig B40, making note of the various PCBs inside while identifying the best way to go about hacking the device. The coffee maker is controlled by a PIC, and rather than try to re-engineer things from the bottom up, he left the core of the machine intact and focused on the control panel instead.

He disconnected all of the unit’s buttons from the control board, routing them through an Arduino before reconnecting them to the machine. This essentially rendered the machine inoperable unless triggered by the Arduino, giving [Andrew] control over the brewing process. He wired in an RFID reader from SparkFun, then got busy coding his security/inventory system. Now, when someone wants coffee, they merely need to swipe their office access card over the machine, which enables the use of its control panel.

As you can see in the video below the system seems to work well. If we were to offer some constructive criticism, we would suggest ditching the laptop and rolling the RFID reading/verification into the Arduino instead – other than that, we think it’s great.

Continue reading “Securing Your Keurig With RFID” →

Smelting Metal In Your Microwave Oven

December 19, 2011 by Mike Szczys 39 Comments

Grab some scrap metal and a microwave oven and you’ll be casting your own metal parts in no time. [Mikeasaurus], who is known for doing strange things like making Silly Putty magnetic or building his own spray paint bottles, doesn’t disappoint this time around. He read about microwave smelting in Popular Science and is giving it a shot himself.

The image above shows him pouring an ingot. He build an insulated brick enclosure inside of the microwave oven, then set it to go ten minutes for a 50/50 lead/tin mixture, or fifteen minutes for silver. This will vary based on the power rating of your microwave. You can see in the video after the break that the setup gave him some trouble shortly after pouring. It wasn’t a problem with the molten metal, but spontaneous combustion of the rigid foam insulation that did him in. We shouldn’t say ‘I told you so’, but that insulation says right on it that it’s flammable!

This isn’t the first time we’ve looked at casting metal melted in a microwave. Check out this other version posted back in 2005. Continue reading “Smelting Metal In Your Microwave Oven” →

Web-enabled Coffee Maker Over-complicates Your Break Time

December 5, 2011 by Mike Szczys 18 Comments

Some think that grinding the beans and filling the coffee maker is part of the coffee-drinking ritual, but [Jamie] isn’t one of them. Instead, he’s been working to make this coffeemaker a web-enabled device. He built it as part of a class project, and has implemented most of what you need to make a cup of Joe automatically.

You can see a small pump attached to the back of the coffee maker. It sucks water from a pitcher (slightly visible to the left of the coffee maker) to fill the reservoir. He experimented with a couple of different water level sensing solutions. His most recent is a PCB with several traces of different length. As those traces are covered by water, a voltage can be read via ADC to establish water level.

He’s using an Arduino and Ethernet shield to add connectivity for the device. The problem is that there aren’t enough ADC pins left on the Arduino to read the water level sensor. Because of this, he added a self-build shield that uses a PIC to do the ADC measurements and push digital data across to the Arduino. A bit complicated, and it doesn’t load the grounds automatically (yet?). But that’s not to say we don’t appreciate complicated coffee hacks.

Kitchen Hacks: Improving An Espresso Machine

November 27, 2011 by Brian Benchoff No comments

The heat sensor in [Cameron]’s espresso machine doesn’t work very well. He sees some pretty crazy variations in temperature when pulling an espresso shot, and when the boiler is just sitting there the heater element will heat the water full-bore then shut off for a while. Since this is a pretty low bar from a control theory standpoint, [Cameron] decided on a PID makeover on his espresso machine.

Instead of going with a commercial PID controller like we’ve seen on a few kitchen hacks, [Cameron] decided to roll his own Arduino derivative based on an ATMega328 microcontroller. The newly designed board reads the state of the ‘Steam’ button, a few relays for controlling the heater and the pump, and of course an LCD display.

[Cameron] still has to do a little tweaking to get his PID algorithm down, but already the new control board keeps a much more stable temperature than the old thermostat. The fancy new bezel and LCD display adds a lot of techy class to his espresso machine, to boot.

Kitchen Hacks: Home Made Meat Smoker

November 23, 2011 by Brian Benchoff 21 Comments

[Matt] noticed an overabundance of sous vide builds in the past week, so he decided to throw his Home made meat smoker into the ring. There’s not many things more delicious than a nice cut of smoked meat, and the fact that it’s very similar to the sous vide hacks we’ve seen is an added bonus.

[Matt] decided to build a ceramic smoker like a Big Green Egg. He took a cue from [Alton Brown] and used two terracotta planters and a hot plate for the smoker. For controlling the hot plate, the cheap $35 PID controller we’ve seen in a few sous vide builds was used. The PID can’t control the 7 amps of AC that the hot plate needs, so [Matt] used a solid-state relay he had lying around.

A stainless steel mixing bowl was placed on the hot plate for wood chips. So far, [Matt] has run his smoker for more than 12 consecutive hours, and the results are really promising – there wasn’t much change in temperature between the chill of the morning and the heat of afternoon. [Matt]’s build is great and perfect for venison jerky now that deer season is coming up.