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Messages - nabilt

17
General discussion / Re: Another software-hackable watch
http://kck.st/HumIV5

I also backed this project even though I have never worn a watch in my life on a regular basis. I'm excited for the fitness applications like cycling because of the e-paper display and accelerometer. The product isn't open source, but they do have an open source SDK. I'm interested because I'm building an open fitness device with similar specs, but won't be a watch.

Btw, these guys are the real deal. They are backed by a well known startup incubator, Y Combinator, and have released a previous product. That said they may have problems fulfilling all of these orders so back at your own risk.
19
General discussion / Re: Free Seminar - STM32 (ARM Cortex-M0)
Great find. Got one of these boards, but haven't done any big projects yet. I tend to stick with what I know, which is LPC. How do you guys feel about the NXP vs ST debate? From what I've seen you tend to get more bang for the buck with NXP.
20
General discussion / Re: DIY Super capacitors made out of Graphene
Good idea about using the substrate as the insulator. That is probably the first thing anyone should try if they attempt this project.

Haven't read the paper from the researchers using the camera flash, but what I've read from other papers is the resulting graphene is not as super conducting as the laser method.
21
General discussion / DIY Super capacitors made out of Graphene
There has been a video going around from researchers at UCLA about building super capacitors using a Lightscribe DVD writer and graphite oxide (GO), which I think looks really amazing and am interested in reproducing. I figured others might be as well so here is what I know so far.

UCLA Video
http://http://www.youtube.com/watch?v=_oEFwyoWKXo

Similar older video from Rice University that used a CO2 laser
http://http://www.youtube.com/watch?v=3O4YV0mrkfQ

Full Paper
http://http://hackadaycom.files.wordpress.com/2012/03/el-kady-som.pdf

Summary paper
http://http://hackadaycom.files.wordpress.com/2012/03/laser-scribing-of-high-performance-and-flexible-graphene-based-electrochemical-capacitors.pdf

Popular method of producing GO - Modified Hummer's method (pay wall)
http://http://pubs.acs.org/doi/abs/10.1021/nn1006368

Paper I found on google about producing GO. Appears similar to Hummer's method.
http://http://www.rsc.org/suppdata/nr/c1/c1nr10549c/c1nr10549c.pdf

I'm not a chemist so take everything with a huge grain of salt.

Producing GO
Googling around it appears GO is cheap to produce, but I can't seem to find any suppliers. It is produced from highly pure graphite (carbon atoms structure in a lattice - stuff commonly known as pencil lead) using Hummer's method (linked above). I haven't paid for the article yet, but the abstract says, "We have found that excluding the NaNO3, increasing the amount of KMnO4, and performing the reaction in a 9:1 mixture of H2SO4/H3PO4 improves the efficiency of the oxidation process". The last article linked above says, "9:1 mixture of H2SO4 (95%) / H3PO4 (85%) [360:40 mL] was added to a mixture of graphite powder (3.0 g, 1 wt. equiv.) and KMnO4 (18.0 g; 6 wt. equiv)".

After isolating the solid GO from the liquid it is dried and neutralized to produce a powder. From there it is mixed with water and vacuum filtered or cast into a mold using a centrifuge. The result is what we see in the videos.

Producing Graphene from GO (The cool part)
According to Wikipedia, "graphene is an isolated atomic plane of graphite". It is super conductive, 97% transparent and flexible. There is hope that this relatively new material can be used to create flexible circuits and high frequency transistors. IBM was successful in creating transistors with a 100GHz switching frequency. Researchers at Cornel have shown devices can be created by printing graphene using an inkjet printer http://http://en.wikipedia.org/wiki/Graphene#Graphene_transistors.

There are many methods of producing graphene. One method uses scotch tape to peel layers off graphite. http://www.youtube.com/watch?v=ehvksWx3AJQ&feature=related[url]. Recently the most interesting method is to use lasers to strip oxygen atoms from GO, which is what the researchers did in the video above. Cheap and simple.

[b]Making a supercapacitor[/b]
I'm still reading about their construction, but it appears the researchers use either an electrolyte gel or other type of high performance insulator. In one example they used Celgaurd 3501 [url]http://www.ldcgm.com/Celgard/CELGARD-4550.pdf. Both types don't look like they are easy to find or make.

Conclusion
If you have access to GO sheets then the project looks doable. It seems you might not get high energy and power density unless you use the aqueous electrolyte or ionic liquid, which I'm not sure is readily available. Otherwise, making GO at home does not seems feasible because of the high concentration of acids involved.
23
General discussion / Re: How do you manage your parts?
[quote author="esden"]
It would be nice if we could just drop an ID like [tt:]res-0402-10k[/tt:] into Octopart and get a full list of 0402 10k resistors and find the cheepest source for it.[/quote]
That is what I am trying to do with my web app. It tries to extract useful data from the package, value and description and finds the cheapest part. I had the same problem with existing tools because they expect your BOM to have exact part numbers before they do a search. Eagle's Design Link tries to solve this problem, but it doesn't do a very good job.
24
General discussion / Re: How do you manage your parts?
I vote for XML/JSON with a slight edge for JSON cause it would make life on the web easier. I like the flexibility and self documenting structure these formats provide. However, arhi's point about overhead is a valid one. Parsing JSON that Octopart returns has become the bottleneck for my web app. I still have to experiment with other libraries and possibly multithreading to see if I can speed things up.

Other formats that might be worth researching:

Product data eXchange
Arena uses this, but I've never heard of it - http://www.arenasolutions.com/pdxviewer/

Since Eagle moved to XML it would be interesting to see what schema they use. Do they add the data they find from Design Link into the BOM? http://www.adafruit.com/blog/2011/11/04 ... reenshots/

Altium also has their Live Links to supplier data. I'll investigate to see what format they use as well.
http://altiumwiki.onconfluence.com/disp ... plier+Data
25
General discussion / Re: Few more ITead Mystery PCBs
[quote author="arupbsk"]Today I received my fist itead order with two MYSTERY PCBs.
EDIT: First one is a cute breadboard type PCB designed by Zachary Heilig. Board looks like Perma-Proto
[attachment=1][/quote]

Hehe. I received the same board. I also got something called the Smart Modular Platform http://http://bigdinotech.com/smp/. I emailed the guy, but didn't get a response. It is looks like a power distribution board controlled by an atmega328 and some relays.
26
General discussion / Re: How do you manage your parts?
Octopart just tweeted a free tool for BOM management. You can import a CSV file into a project and auto fill details using Octopart.
http://http://www.arenasolutions.com/partslist/?utm_source=Twitter&utm_medium=tweet&utm_term=arenapartslist&utm_content=ECAD%2BBOM&utm_campaign=plpromo

Their main tool is a more comprehensive product with collaboration features and stuff. They charge $79 per user per month, which includes training, tech support, upgrades, etc.
http://www.arenasolutions.com/
27
General discussion / Re: How will SOPA and PIPA affecr open hardware?
It is really too bad that our governments are prioritizing copyright over so many other issues. Here in Canada we are getting our own version of the DMCA, which will prevent breaking digital locks to exercise our fair use rights. It appears to be the first step in more SOPA like legislation.

To answer the original question of this post, I think bills like SOPA and PIPA have shown people why open source is so important. It is difficult to convince people about freedom when they are living a free life. Maybe these new bills and the privacy concerns with Google, Facebook, etc ... will wake people up.
28
General discussion / Re: How will SOPA and PIPA affecr open hardware?
Quote
arhi
We can hope, but no, there's no freaking way they can go under since they have more money then God. And the powers that be respect money too much...

Which is why I agree with people like Marco (http://http://www.marco.org/2012/01/20/the-next-sopa). The internet should keep this momentum going and boycott the content publishing industry. Stop watching movies, tv, netflix, hulu, amazon vod, ... Stop buying books, audio books, magazines, ... Stop listening to radio/satellite radio, ... Stop buying mp3s, CDs, records, ... You get the idea.

Just like Cory's suggestion to support open standards we should support independent media like podcasts, buy directly from the artist and most importantly stop handing over our rights to companies like Apple or Facebook who lock us into their ecosystem and do what they want with our information.

It is a difficult task and I certainly haven't followed my own advice to the letter, but I'm trying. Most of my entertainment has been supplemented by internet video or audio. The only Apple product I use is my Macbook (trying to find a replacement) and I try to use the library instead of buying books.
29
General discussion / Re: How will SOPA and PIPA affecr open hardware?
I'm sure you guys have seen Cory's talk at 28c3 titled "The coming war on general computation", but here is the link incase you haven't http://www.youtube.com/watch?v=HUEvRyemKSg

He talks about how the war on copyright is a prelude to the war on general purpose computing. For example, toy companies might try to cripple 3D printing technology it threatens their business model. He has many real life examples and is worth a watch.

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