Hackaday Links: October 28th, 2011

An accidental radial engine

Hack A Day’s very own [Jeremy Cook] was trying to figure out how to push four ‘arms’ out one at a time. What he came up with is a very nice model of a radial engine. Everything was cut on a CNC router and a motor from an air freshener provides the power.

Using a candle to produce light

[Chris] sent in his Candela Amplifier. It’s a Pentium 4 heat sink with a very bright Cree Xlamp LED attached to the base. A bunch of Peltier thermoelectric units are attached to the underside of the heat sink. Put the whole thing on top of a candle, and you can light a room. With a candle. Oh, he’s selling these, by the way.

Objectification and video games?!

We really feel sorry for our lady readers. Guys have so many choices for Halloween costumes, but just about every costume available for women can be reduced to, “Sexy [noun].” Whelp, here’s the Sexy Game Boy, just in time for Halloween. [kazmataz] gets a few bonus points because she went with the DMG-01. It’s better than Sexy Chewbacca, so she’s got that going.

Prototypable 32-bit uCs

[Ng Yong Han] wrote in to tell us about some newish 32-bit PICs that are floating around. The datasheet for the PIC32MX1xx/2xx chips is pretty interesting – USB support and an audio and graphics interface. Oh, they come in PDIPs for ease of prototyping as well. We haven’t seen much from the PIC microcontroller faction recently (Atmel is winning the holy war, it seems). Anybody feel like building something with these?

Makerbot dual extruder

[Lomo] at TU-Berlin is taking a class in rapid prototyping. He built a second print head for his department’s Makerbot Cupcake with a few other students. The result are pretty impressive, although from what we’ve seen, it’s generating the G-code that’s a pain in the butt.

24 thoughts on “Hackaday Links: October 28th, 2011

      1. Correct it doesn’t change it’s name because it’s called a thermoelectric element. The terms Peltier and Seebeck refer to a process or effect not a piece of hardware so it doesn’t become a Peltier device until it’s being used to create a temperature differential using electricity and when it’s used to do the opposite it’s a Seebeck device.

        Same way that an electromechanical mechanism made from magnets, a coil and slip rings is called a motor when it’s used to convert electrical energy into mechanical and a generator when it does the opposite.

        The definition is by function not construction.

    1. A candle puts out roughly 0.3 lumens per watt, and a small paraffin candle like that puts out roughly 150 Watts of power, which gives you 45 lumens, which is 1/20th of a 60 Watt lighbulb.

      A typical white LED gives out 60-70 lm/Watt, and the efficiency of a typical peltier element is roughly 6-7%, which gives you a maximum power of 10 Watts in electricity if all heat is trapped, but probably more like 2-3 Watts because most of it escapes.

      Still, even at 2 Watts of electricity produced, the LED easily beats the candle in luminous power, and combined they should produce close to four times the visible light.

      You’d be better off with a mantle lamp though, because it gives you directly 1-2 lm/W so you get 150-300 lm directly out of the heating power of the candle.

    2. Besides, since we’re talking of low-light conditions anyways with only a hundred odd lumens to light a room with, you see much better with the blue and yellow light given off by the LED than the red and yellow light given off by the candle.

      That’s because your scotopic, or night vision, works in the blue wavelenghts, while your photopic or daylight vision works in the green wavelenghts. The peaks of the sensitivity curves correspond to sunlight which peaks between 469 – 555 nm, shifting to blue when dark and green when light, because blue photons carry more energy and are easier to detect from all the noise when the light levels drop, while green is the color of all plantlife which are kinda important to see.

  1. @fartface – the idea that this based on, waste heat harvesting or reclamation is not that the candle is replaced by the led but that it is augmented by it using heat that would otherwise be wasted. That said this is a bad implementation as it is swapping wasted heat for wasted light due to the poor design. The candle holder should be glass or some other transparent material.

    Now who do I know who is small enough to take these old heatsinks up my chimney ? :-)

    1. nope. I thought so too. Especially since it has a built-in oscillator, lots of peripherals and 5 v tolerant beefy IO. Seems like a nice addition to the Diligent SW environment (w/ or w/o their bootloader).

  2. Wondering if i should build one of these “Candela Amplifiers” just for the hell of it ;-O

    Does anybody agree with me if i say it looks like it’s two 40 Watt peltiers stacked ontop of each other and connected in series ?

    Got a big heatsink, some Peltiers and Luxeons + time to burn…

  3. Glad to see that semiconductor companies such as Microchip (PIC32) and NXP (Cortex-M0) are not completely abandoning DIP packages for their 32-bit offering; the PIC32 and Cortex-M0 families respectively. Having said that I’d like to see more Flash and RAM integrated into these low pin count parts…Maybe 64KB-128KB Flash and 8KB-16KB RAM

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