Charting The Efficiencies Of Boiling Water

June 2, 2012 by Brian Benchoff 32 Comments

Water takes a lot of energy to heat up. If you’d like evidence of this, simply jump into a 50° F swimming pool on Memorial Day. Despite the difficulty of heating water, that simple act accounts for a lot of industrial processes. From cooking a steak to running a nuclear reactor, there isn’t much that doesn’t involve heating water.

[Tom Murphy], Physics prof at UCSD decided to test out exactly how efficiently he could boil water. Armed with a gas stove, electric kettle, microwave, and a neat laser pointer/photodiode setup on his gas meter to measure consumption, he calculated exactly how much energy he was using to make a cup of tea.

The final numbers from [Tom]’s experiment revealed that a gas stove – using a pot with and without a lid on large and small burners – was about 20% efficient. A gas-powered hot water heater was much better at 55% efficiency, but the microwave and electric kettle had a miserable efficiencies of around 15 and 25%, respectively. There is a reason for the terrible inefficiency of using electricity to heat water; if only the power from the wall is considered, the electric kettle put 80% of energy consumed directly into the water. Because the electricity has to come from somewhere, usually a fossil-fueled power plant that operates at around 30% efficiency, the electric kettle method of turning dinosaurs into hot water is only about 25% efficient.

The take-home from this is there’s a lot of power being wasted every time you run a bath, make some coffee, or wash the dishes. We would all do better by decreasing how much energy we use, much like [Tom]’s efforts in using 5 times less power than his neighbor. Awesome job, [Tom].

A Wedding Cake Made Out Of LEDs

May 28, 2012 by Brian Benchoff 15 Comments

[Andrew] wanted to do something special for his wedding. Since he and his fiance [Missy] decided on a cupcake wedding cake, [Andrew] decided to wow his guests with an RGB LED cupcake holder.

The tiers of [Andrew] and [Missy]’s cupcake holder are made of acrylic laser etched with a damask pattern. These tiers are supported by a cylinder embedded with RGB leds that provide edge lighting for the acrylic panels. The effect is a series of permutating lights that illuminate the cupcake holder with every imaginable color. On the top of the cupcake cake, there’s a great cake topper made of frosted and laser cut acrylic that has the same color fade effect as the cupcake holder.

On the electrical side of things, the cupcake holder has 44 LEDs on all it’s levels. FETs driven by a 40-pin PIC18F control all the LEDs and the whole piece is powered by a computer power supply.

It’s an awesome build, especially considering it was finished just days before the wedding. After the break, you can check out a few more videos showing off the beauty of [Andrew] and [Missy]’s wedding cake.

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Your Face In Chocolate

May 23, 2012 by Mike Szczys 19 Comments

We think in might be absurdly vain, but wouldn’t it be fun to give everyone in your family a chocolate modeled after your mug this holiday season? [Eok.gnah] has already worked out a system to make this possible. It consists of three parts: scanning your head and building a 3D model from it, using that model to print a mold, and molding the chocolate itself.

He used 123D to scan his face. No mention of hardware but this face scanning rig would be perfect for it. He then cleaned up the input and used it to make a mold model by subtracting his face from a cube in OpenSCAD. That needs to be sliced into layers for the 3D printer, and he used the Slic3r program which has been gaining popularity. Finally the mold was printed and the face was cast with molten chocolate. We’d suggest using a random orbital sander (without sand paper) to vibrate the bottom of the mold. This would have helped to evacuate the bubble that messed up his nose.

You know, it doesn’t have to be your face. It could be another body part, even an internal one… like your brain!

A Simpler Sous-vide Hack

May 16, 2012 by Mike Szczys 7 Comments

Here are the contronl modules for a sous-vide project over at Nerdkits. [Humberto] and crew continue doing a great job of focusing a project on one goal, then explaining the steps needed to get there. In this case they wanted to build their own sous-vide appliance that was cheap, and didn’t really require the user to deal with mains voltage. We like it because most of the parts can be found at a hardware store and big box store.

He started with a slow cooker, which is pretty standard. Next he needed a way to switch power to the device. Instead of using a solid state relay, he went for a standard dimmer switch. It’s build into a double gang electrical box, and controls an outlet which is occupying the second position in that box. Now current to the slow cooker is limited by the position of the dimmer. The next task was to add a cardboard frame which marries a servo motor to the dimmer’s knob.

With the control scheme in place [Humberto] needed a feedback sensor. He built his own water proof temperature probe by covering an LM34 temperature sensor with shrink tube and sealing the ends. Just one probe in the cooking water isn’t very reliable so he added a second between the slow cooker’s base and ceramic vessel to improve the performace of the PID algorithm. He goes into detail about that in the video after the break.

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Custom Heaters For A DIY BBQ Smoker

April 4, 2012 by Brian Benchoff 4 Comments

Spring is in the air, and with that comes savory meals cooked over the course of dozens of hours. While preparing for your yearly allotment of pork and beef, check out [Brett Beauregard]’s custom heater elements he built for a DIY wood smoker.

This build follows the very successful smoker [Brett] built last year. This year, he’s using the same toaster oven heating elements, only cut down to make the heater smaller and more efficient. Basically, [Brett] is making a small cartridge heater out of the equipment he already has.

After cutting the toaster oven heating elements to length, [Brett] reamed out the ends to expose the nichrome wire. A short hit with a TIG welder bonded the lead to the heating element. Insulated with furnace cement, [Brett] had a custom heater perfect for charring chunks of mesquite or hickory.

Meat smokers aren’t very complicated – they can be built with a flowerpot and a hotplate, and will still cook up a delicious dinner. We might have to borrow [Brett]’s technique when we build this year’s smoker.

Preheat Alarm Added To A Basic Kitchen Oven

March 7, 2012 by Mike Szczys 21 Comments

[Justin] didn’t want to keep checking if the ‘oven heating’ indicator light had gone off before popping his unbaked edibles into the oven. Many models offer a buzzer to let you know when the chosen temp is reached, but for folks who own a basic oven model there’s just a light that tells when the heating element is getting juice. Not to worry, he plied his circuit design skills and built a buzzer to alert him when the oven’s ready.

It only took a few components to accomplish the task. [Justin] uses a pair of NPN transistors triggered by a photoresistor. One transistor is responsible for switching on the buzzer, the other transistor is driven by the photoresistor and controls the base of its companion transistor (see the schematic for a better understanding).

He designed and etched a small PCB to host all the parts. As you can see above, it mounts over the indicator light and is powered by a 9V battery. There’s an on/off switch to the right so the buzzer doesn’t keep triggering while cooking, and a potentiometer allows him to fine-tune the photoresistor sensitivity.

New Extruder 3D Prints Tasty Treats Using Chocolate

February 29, 2012 by Mike Szczys 18 Comments

If you’ve never felt at home with a piping bag in your hands this chocolate extruder will come to your rescue. It can replace the plastic extruder head on your 3D printer (RepRap, Makerbot, most 3-axis CNC machines, etc.), letting you turn your digital creations into decadent reality.

The head uses a progressive cavity pump to feed the chocolate from a reservoir through the printing nozzle. It’s important to keep the chocolate warm or it will set up so when [Tomi Salo] designed the print head he included a heat shroud through which warm air can be circulated. He uses a shoe dryer to source the hot hair which is patched into the heat shroud with a length of tubing.

This extruder can be 3D printed but be careful what material you use. [Tomi] mentions that PLA is ‘sort of food-safe’ but ABS is not. We wonder if the design could be altered for milling out of aluminum or stainless? At any rate, if you’re going to give it a try you might find [Tomi’s] advice on working with chocolate useful.

[via @clothbot]