Science Projects

[Kees] wanted a remote for an XBMC audio system. He had a classic T65 Dutch telephone in one of his project boxes and thought this phone with the addition of a Raspberry Pi he could have a functional media remote with classic lines and 70s styling. Each of the digits on the phone were wired up to a small solderless breadboard. With a handful of resistors, [Kees] set up a simple pull up/pull down circuit feeding in to his Raspi’s GPIO input. With a short Python script, [Kees] managed to map the buttons to XMBC’s play/pause, volume up/down, next, and previous commands. There were a few buttons left over, so those were mapped to online radio stations, playlists, and a strange setting known only as ‘moo’. We’re not sure what that button does, but you can see the other functions of this XMBC phone remote in action in the video below. Filed under: phone hacks, Raspberry Pi

Check out Microphone Driven LED Heart: Blooper Reel by getupgetdowning a short 6 second film for the Adafruit #adafruit6secs electronic film festival (Youtube playlist here for all the entries on YouTube).

A submission from the Adafruit 6 second electronics film festival explained: You’re looking at ~24 hours of continuous AVR flashing compressed down into 6 seconds. While I won’t be releasing the connecting PCB just yet (i’m still beating down a few issues and refining the BOM), I thought it would be good to supply the scripts I used to do the actual time lapse since it was non-obvious from a “oh dear, the contest entry is due in Source code and more here!

Once upon a time, a nerd met a girl. Things happen as they do, and eventually [Ben] wanted to create the be-all, end-all engagement ring. It’s a simple titanium affair with 23 stones around the perimeter. What makes this ring so cool, though, is that it lights up whenever [Ben] and his girl are holding hands. The metalworking portion of the build was about as easy as you would expect machining titanium to be. After the ring was cut off its bar stock, [Ben] brought it over to a mill where 23 holes for each of the stones were drilled. The stones were affixed to the ring with  jewelers epoxy and the entire ring was buffed to an amazing shine. The electronics are where this project really shines. Putting a battery of capacitor inside a ring is nigh impossible, so [Ben] decided to power the LEDs with an inductive charging circuit. A coil of wire wound around kapton tape serves as the inductor and a small SMD capacitor powers three very bright and very tiny LEDs. The inductive charging unit itself is a masterpiece of hackery; [Ben] wanted the ring to light up whenever he and his ladyfriend were holding hands. To do this, [Ben]‘s inductive charger is also a wearable device: a large coil of wire is the charger’s transformer and was would to fit around [Ben]‘s wrist. The entire charging circuit can be easily hidden under a jacket sleeve, making for a nearly magical light-up ring. An awesome piece of work, and one of the best jewelry builds we’ve seen in a long time. You can see the inductive coupling and shining LEDs in the video below. Filed under: led hacks, wearable hacks

Thermoelectric devices are seen very often in various appliances. Small refrigerators, semiconductor chip coolers, medical chillers. Thermoelectric effect works in both directions – it can generate temperature difference when current flows or it can generate current when temperature difference is applied. About thermoelectric effect It is known for more than 100 years. There are several scientists who discovered this effect in one or another way. Probably you’ve heard Peltier effect. Jean Charles Athanase Peltier discovered that if you apply electrical current to junction of two materials it gets cold or hot (depending on current direction). The reverse effect when electricity is generated due to temperature difference was discovered by Thomas Johann Seebeck. So this effect is Honored by his name. But for now lets focus on Peltier effect and thermoelectric devices. Peltier element The most common element is ceramic coated device with two wires popping out. They are made of semiconductor materials. One is N type and another is P. Instead of single Junction there are hundreds of them – simply speaking they are connected in series, but thermally they are parallel. Multiple joints increases the surface are and so the efficiency. If you look inside the Peltier element you will see a sandwich made of small silicon bricks electrically connected in series. The ceramic plate is used as carrier and heat transferee. Each individual pair works same way, the heat is absorbed from one side of plate and transferred to another. If we go deeper in to working physics we can see that when current flows electrons in N-element are pushed against the current while holes in P element same direction as current. Both are mowing from one side of element absorbing heat. The heat is carried to another junction. Hope this is enough for understanding what happens there. And again. If we apply different temperatures to both sides of plates we get electricity (Seebeck effect). It is not common usage as it’s efficiency is very low. Some space programs have been using those as alternative energy source. So why thermoelectric coolers aren’t used widespread? It seems that they are beneficial in many ways including solidness (no moving parts), failure proof if used correctly and are easy to control. It appears that they aren’t as efficient we would like it to be. Compressor based systems are several times more efficient which keeps them in refrigerator business. Peltier elements can reach temperature difference between surface to about 70ºC. The bigger difference is the worse efficiency becomes. So it is used in compact coolers, in environmental friendly applications where efficiency isn’t the key. You’ve probably seen an USB powered cooler for soda cans – it wouldn’t be possible without thermoelectric coolers. Peltier elements are pretty standardized devices and you can tell some features from its ID. For instance I have couple of TEC1-12705 elements what can be decoded in to; TE – thermoelectric; C – size. C – standard; S – small; 1 – number of stages. Normally 1. 127 – the number of P-N couples inside the plate; 05 – current rating. In this case 5A. As all semiconductors it is sensitive to overheating. It is advised not to power Thermoelectric element without heat-sink on hot side. Probably you can connect it for a short time to determine which side cools and which heats. Typical cooler application If you are going to build a cooler, your typical setup should be as follows: It is mandatory to put a heat-sink on a hot side of Peltier element which would take a transferred heat. For better transfer put thermal paste. It is good idea to have temperature sensor on heat-sink in order to avoid overheating. On cold side of plate you can put what ever you designed – a cold plate, another heat-sink with blower to get cool air or what ever you need. Here also you can put a temperature sensor to keep cold point. If hot heat-

A spaceship simulator sounds fun. But a spaceship disaster simulator is pure win. Members of the LHS Bikeshed hackerspace over in the United Kingdom poured their hearts and souls into this build. Now they’re taking the show on the road, letting attendees of Maker Faires all over the UK try their hand at beating the Kobayashi Maru disaster simulation. The real question is how do you take your simulator on the road with you? You build it in an old camper (or caravan as the Brits call it). The towable sleeping quarters were gutted to make room for the well-crafted command center seen above. The demonstration video also shows off some bulkhead doors which open to reveal a wiring mess that must be fixed to prevent a disaster. Not only does the physical build really sell the concept, but the audio and video produced for the simulator look fantastic too. The link above is a recent post, but you should dig through their archives see multiple steps during the project build. It makes us thing we should keep going with our VW Bus hacking. Filed under: Hackerspaces

N9 Satellite Dish Control. Travis writes - Here, my Nokia N9 in Europe is commanding my satellite dish in America. Clicking on a target physically moves the dish to aim in the appropriate direction, readjusting as the target moves in the sky.

That's why you make measurements...

Arduino Blog – The Mood Lamp recognizes your facial expressions and turns them into light. The Mood Lamp project by Vittorio Cuculo, is a system using interactions to communicate an emotional state to a physical object and receive back  a coherent response. In particular, through your facial expression you communicate your emotional state to an RGB color lamp . The lamp, at this point, will respond to the interaction by changing the color of the light emitted in accordance with the emotional state inferred. The aim of the systems is to remove the mediation between human and machine typical of classic interfaces. Among the modes of natural interaction we usually have gestures, gaze tracking and facial expressions. The latter are particularly relevant because they play a fundamental role in nonverbal communication between human beings.

Neoden TM240A Pick and Place machine – first impressions « Circuits@Home. Some time ago I noticed that I’m spending more time building boards and less time developing and needed to increase my manufacturing capabilities. After thorough reading Dangerous Prototypes’ Chinese desktop pick and place machine forum thread I got in contact with a factory and bought TM240A – the big brother of TM220A. Earlier this week a DHL van carrying 70kg crate pulled in my driveway. After a day of hands-on learning I started building boards. This article was written after 2 days of using the machine and contains my first impressions as well as a couple of hints. First, it is a real Chinese machine – well built, simple, and reasonably priced. At the same time, an owner must be prepared to fix mechanical issues and work around software bugs without relying on manufacturer’s support – the folks at Neoden are helpful but due to a time difference a reply to an e-mail would arrive the next day. Fortunately, the user base for these machines is expanding and the thread linked above as well as videos by Ian@DP and other people provide lots of useful info. I was ready to face issues like air lines clogged by small pieces of styrofoam, non-functioning vacuum pumps and such; luckily, the only problem out-of-the box was racked gantry causing feeding fault. Thanks to this post in DP thread I was already aware about the symptoms as well as the fix – so I fixed it. While doing this I learned that to implement the fix no tools were necessary – a typical human finger jammed between the front support and the gantry works just as well as originally specified screwdriver.