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Ask HN: What are you working on?

114 points by jellisjapan ↗ HN
This question comes from a great thread from a while back that I really enjoyed (http://news.ycombinator.com/item?id=700662), so I thought with the new year here, it'd be a good time to ask again.

I'm still developing readthekanji.com, a site for helping Japanese students learn to figure out how to read kanji. It's been one of the best learning experiences, and I'm loving every minute of it.

So what projects are you currently working on, or planning for the new year? Is it a startup, or research perhaps? And how's it going?

251 comments

[ 3.0 ms ] story [ 238 ms ] thread
jgrahamc
I am working on making 500 of these: http://www.jgc.org/blog/2008/03/building-temperature-probe-f... for schools in Uruguay.
jacquesm
You can possibly get rid of the pair of 9V batteries by using a floating ground that you make with two resistors.
jeromec
But then what would he use for the voltage source, + and - 4.5V? It appears he wants the + and - 9V available for the amplifier. But my EET is extremely rusty.
jacquesm
The 5 V from the USB.

Leave the opamp with it's ground connected to the joint between the two resistors, choose the bias so it drives the output from the -2.5 V the opamp sees (which really is the 0 from the computer) to the +2.5V (which is the +5 of the computer).

jeromec
I'm only giving the circuit a cursory look, but I thought he wanted a 9V reference voltage added to the sensor voltage going into R7. But I guess a lower reference voltage may be adequate too.
jacquesm
The midpoint voltage of the voltage divider used for the reference is 0.45V, well within the -2.5 to +2.5 swing.

The reason why I think it matters is that batteries are a nuisance, they run empty and will cause a problem with long running experiments, so it's worth the extra time to engineer them out of the circuit.

From what I can see they're only used to power the op-amp.

The 'floating ground' trick is s.o.p. when designing op-amp circuitry that needs to be fed from a single supply.

jeromec
I said reference voltage, but I meant the voltage for the summing amp would need to be 9V if that's the step up range he's going for. I totally agree about eliminating the batteries if possible; I just wasn't sure how to get adequate voltage available to the amp without the 9V batteries. But again, it's been many years since I've even looked at a schematic. The floating ground idea looks extremely cool though.
jacquesm
Reading the post again he might be able to completely get rid of the whole circuit by placing two Ge diodes in series with the 0 terminal of the LM35, that will raise the 0 by 0.4 V, just enough to get over the threshold.
jeromec
Wow, now I know where to look the next time I have a hardware project. Nice.
jgrahamc
Agreed. I am redesigning it for the production version. I'd like to pull everything from the USB if possible.
jacquesm
Have you tried simply raising the ground of the LM 35 by placing a diode in series with the 0 terminal?

That way you might just add a single 10ct component and get rid of the problem completely.

Just enough to raise the ground of the LM35 above the input sensitivity threshold.

One Si diode would probably work, two Ge in series would be slightly better (because you get more range).

So that would be:

          +
          |
          |
      +---+--+
      | lm35 +---- out
      +---+--+
          |
         ---
         \ /
          v
         ---
          | 
          |
       ---+-- gnd
The diode is 'up side down', you simply use the voltage drop to raise the 0 of the lm35 (like a zener diode), it doesn't know any better and will add the output voltage to the ~0.6 V the diode provides.
joe_bleau
What happens to the voltage across the diode when the temperature changes? Looks to me like you've just replaced a calibrated temp sensor with two sensors in series!
jacquesm
The temperature of the diode will change right along with the temperature of all the other hardware, it's not as though you'll go out of your way to get the diode heated up.

The way it's drawn is not the way it is built, the diode would normally sit near the computer end of things, not right on top of the sensor.

The thermal drift of the other circuit is at least as large as that of a diode at room temperature, probably a whole lot larger.

joe_bleau
I'm really surprised that the mic input is DC coupled. That's _very_ odd. But then I've not seen the schematics (anyone got a link?), so maybe it is.

I'd certainly consider a low power rail-to-rail op-amp and dump the 9V batteries.

jasonlbaptiste
I'm interested/ been heavily exploring:

PCs in the living room (everything from custom linux distro, XBMC Live modified, and windows 7). 140 million HDTVs sold in 2009 alone, hardware is getting cheaper, and content is readily available.

Education space. ie- how do we provide easy access to all the materials that exist out there? My hypothesis: everything we could ever want to learn exists already on the net or can be taught to us by a person we can be connected with in seconds. How do we easily organize it? think more of a directory than a search engine.

Bringing local businesses into the 21st century. Most don't have a website and still use yellow pages. The existing solutions out there suck and are filled with slime.

Email newsletters. Why not create the weblogs inc of newsletters? Look at what thrillist, dailycandy, etc. have done. Create a network of these around a plethora of wide open niches along with building a strong advertising platform for email newsletters (it doesn't exist yet).

Human powered purchasing decisions. How do we help people know what to buy with specific criteria that transcends checkboxes and a search engine? Something human powered is the way to go about it. As geeks, I'm sure you're constantly asked- what phone should I get for price x, features y, etc. Purchases such as these are expensive and spending a few bucks more to get a personalized recommendation would be worth it.

dimarco
turned http://thatpoll.com into a twitter only site to create/answer polls. about to add a feature where if enough people respond to a poll with an answer that isn't included in the original answer set, it automatically gets added.

the funnest part is the deployment method with git and capistrano. so fun that now I have to create some deployment method for my real job. winscp'ing php and swf's onto a production server doesn't feel like the best way to go about things.

arctangent
I am writing a maze generator in Haskell.
steveklabnik
My startup, CloudFab, is doing well. I'll have more to say about that in a few weeks.

In my spare time, Hackety Hack is coming along, got a release out for Christmas, hoping for 1.0 early next month.

Then I have one more small project that's still secret.

Gobiner
I've been working on a codepad.org clone for .NET languages: http://dotnetpad.net

It's been a ton of fun. I do CMS development in my day job and it's nice to build a site that actually does something instead of corporate brochure-ware :)

rman666
I have the following domains: http://blackhatsystems.com, http://bluehatlabs.com, and http://policyworkbooks.com. Does anyone have ideas for them or want to collaborate? Drop me an email.
Shamiq
I've got joytouse.com and notlit.com

(I agree, the first one seems like it would sell devices for hedonic pleasures).

mattyb
I'd like to contact you, but your email address isn't public. It needs to go in the 'about' section of your profile, not just 'email'.
mattyb
Scratch that, I got it from WHOIS.
terryjsmith
Been working on open sourcing a PHP framework I created a while back. Uses MVC, but the primary goals are to be lean and schemaless. It pulls columns from the database and assigns them to variables dynamically so you don't have to update the schema and then worry about the database (most frameworks require you to flush and rebuild). More to come in the next week. It can be found here if you're interested:

http://github.com/terryjsmith/jaxified

misterbwong
quick project/task tracking app. something easy & simple so we can replace the current system we're using (sticky notes and excel ftl...). hoping to open source it.
tachibana
I'm working on an e-learning platform for low-income students in the United States.
khill
A Java library for Tumblr API access with a focus on making it usable for development of a Tumblr Android application.
rebelvc
mobile coupon site for local merchants. It will be live in two weeks on http://dealbk.com
mrtron
I considered building a similar app - good luck!
samdk
I'm working on a collaboration tool built to help government agencies and aid organizations coordinate during emergencies. I helped start it this summer as part of the Humanitarian FOSS Project (hfoss.org).

It was used successfully in beta for Thanksgiving-day feeding coordination and we're getting very close to our first non-beta release.

http://collabbit.org http://github.com/elitheeli/collabbit

If you'd like a look around the demo or are interested in contributing leave a comment or send me an email.

vinutheraj
Is it something similar to Sahana - http://en.wikipedia.org/wiki/Sahana_FOSS_Disaster_Management... ?
samdk
It's related, yes. Both are classified as "Humanitarian FOSS Projects" and Sahana has been worked on in previous years by people participating in the HFOSS Project summer internship, which is where we started Collabbit.

I'm not intimately familiar with Sahana, but from what I understand it's a fairly large system and can do a lot of specific things. Consequently, most of its deployments have been at sites of major disasters or for very large agencies.

Collabbit takes a different approach. Our goal is to facilitate communication inside groups and between groups, rather than to provide a means of accomplishing specific tasks. That means that Collabbit is quite simple and broad right now. While our initial use case was volunteer organizations communicating in New York City, we're hoping it can be a valuable tool for smaller groups as well.

scotje
Although the holidays clobbered my productivity on it, I've been working on a management app for WoW raiding guilds: http://srsguild.com/

But I did start hacking on a fully email based todo/reminder system over the break that I hope to have functional in another week or so.

jbyers
Working on Wikispaces. Thinking about how to make it even better for teachers and students.
baxident
I was recently shown this by a colleague. Will definitely be trying it out with my students soon.
ericclemmons
Besides a small SaaS (that I use internally, but making public to gauge interest), I've been having fun with namespacing Mootools (http://github.com/ericclemmons/mootools-namespace) and using Rhino to generate dependency maps for simple concatenation (which works on most frameworks' dependency scripts so far).
EGF
I have been working on a health\food tracking site www.eat.ly as well as one other unlaunched project.

A simple blog project that has been going well is www.multiplayergames.com which is in need of some buddypress\wordpressMU and design help, but since it continues to perform well I am hesitant to change anything.

Outside of those a handful of other smaller projects:)