HacDC Wiki - User contributions [en]

Schemers

2012-08-29T00:26:33Z

Obscurerichard: Added SICP language module for DrRacket

HacDC is hosting a biweekly study group dedicated to mastering the fabled computer science text, [http://mitpress.mit.edu/sicp/ Structure and Interpretation of Computer Programs], by Harold Abelson and Gerald Jay Sussman, with Julie Sussman. This text is now available for free under a [http://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. We began in May, 2012 and plan to continue this session until we finish the book.

== Logistics ==

Anyone is welcome to attend, normally the meetings are held in person at the [http://www.hacdc.org/location/ HacDC space], in the classroom area, although if that is booked, we may meet in the sanctuary.

=== Meetup Group ===

We keep the master calendar on [http://www.meetup.com/hac-dc/events/calendar/ the HacDC meetup] calendar. Please RSVP If you plan to attend a session.
=== Mailing List ===

Students are encouraged to join the [https://groups.google.com/a/hacdc.org/forum/?fromgroups#!forum/sicp SICP mailing list] where class discussions take place between study groups.

=== Text ===

SICP comes in both print and electronic editons. Amazon sells a [http://www.amazon.com/Structure-Interpretation-Computer-Programs-Engineering/dp/0262510871 new softcover print editon] for about $33. The [http://mitpress.mit.edu/sicp/full-text/book/book.html free online HTML text] from MIT is the most complete and functional electronic version, but there's an [https://github.com/ieure/sicp epub version] ([https://github.com/downloads/ieure/sicp/sicp.epub download]) suitable for ebook readers (Kindle, iPad, etc) available also.

=== Tools ===

Any fully functioning Scheme interpreter will work. Most people in the class are using [http://racket-lang.org/download/ DrRacket] due to its excellent interactive debugger and friendly beginner environment.

Get this software installed to make your life easy:

*[http://racket-lang.org/download/ DrRacket] IDE
*[http://www.neilvandyke.org/racket-sicp/ SICP language module] for DrRacket

It's also possible to use these tools:

* [http://www.gnu.org/software/mit-scheme/ MIT Scheme], the environment the text recommends.
* [http://www.gnu.org/software/guile/ GNU Guile] (built into most Linux distributions, try "sudo apt-get guile" or "sudo yum install guile")
* [http://slidetocode.com/ Lisping], a radical new iPad Scheme and Clojure programming environment

== Exercise Solutions ==

Several study group members are posting their solutions online:

* [https://github.com/benauthor/sicp-in-sheeps-clothing Ben's solutions], including some JavaScript and Python solutions
* [https://github.com/bwestergard/sicp-exercises Bjorn's solutions]
* [https://github.com/obscurerichard/sicp-study Richard's solutions]

== Resources ==

* [http://www.billthelizard.com/ Bill the Lizard] has exercise solutions and ruminations on SICP that started with this [http://www.billthelizard.com/2009/10/sicp-challenge.html 2009 blog entry]
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/ MIT OpenCourseWare SICP class] with video lectures
* [http://www-formal.stanford.edu/jmc/recursive.html RECURSIVE FUNCTIONS OF SYMBOLIC EXPRESSIONS AND THEIR COMPUTATION BY MACHINE] The paper that started it all, describing the theory behind LISP.
* [http://www.utdallas.edu/~gupta/courses/apl/lambda.pdf A Tutorial Introduction to the Lambda Calculus] by Ra�ul Rojas

[[Category:Classes]]

Schemers

2012-07-17T23:45:17Z

Obscurerichard: /* Resources */ Add tutorial link

HacDC is hosting a biweekly study group dedicated to mastering the fabled computer science text, [http://mitpress.mit.edu/sicp/ Structure and Interpretation of Computer Programs], by Harold Abelson and Gerald Jay Sussman, with Julie Sussman. This text is now available for free under a [http://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. We began in May, 2012 and plan to continue this session until we finish the book.

== Logistics ==

Anyone is welcome to attend, normally the meetings are held in person at the [http://www.hacdc.org/location/ HacDC space], in the classroom area, although if that is booked, we may meet in the sanctuary.

=== Meetup Group ===

We keep the master calendar on [http://www.meetup.com/hac-dc/events/calendar/ the HacDC meetup] calendar. Please RSVP If you plan to attend a session.
=== Mailing List ===

Students are encouraged to join the [https://groups.google.com/a/hacdc.org/forum/?fromgroups#!forum/sicp SICP mailing list] where class discussions take place between study groups.

=== Text ===

SICP comes in both print and electronic editons. Amazon sells a [http://www.amazon.com/Structure-Interpretation-Computer-Programs-Engineering/dp/0262510871 new softcover print editon] for about $33. The [http://mitpress.mit.edu/sicp/full-text/book/book.html free online HTML text] from MIT is the most complete and functional electronic version, but there's an [https://github.com/ieure/sicp epub version] ([https://github.com/downloads/ieure/sicp/sicp.epub download]) suitable for ebook readers (Kindle, iPad, etc) available also.

=== Tools ===

Any fully functioning Scheme interpreter will work. Most people in the class are using [http://racket-lang.org/download/ DrRacket] due to its excellent interactive debugger and friendly beginner environment. It's also possible to use these tools:

* [http://www.gnu.org/software/mit-scheme/ MIT Scheme], the environment the text recommends.
* [http://www.gnu.org/software/guile/ GNU Guile] (built into most Linux distributions, try "sudo apt-get guile" or "sudo yum install guile")
* [http://slidetocode.com/ Lisping], a radical new iPad Scheme and Clojure programming environment

== Exercise Solutions ==

Several study group members are posting their solutions online:

* [https://github.com/benauthor/sicp-in-sheeps-clothing Ben's solutions], including some JavaScript and Python solutions
* [https://github.com/bwestergard/sicp-exercises Bjorn's solutions]
* [https://github.com/obscurerichard/sicp-study Richard's solutions]

== Resources ==

* [http://www.billthelizard.com/ Bill the Lizard] has exercise solutions and ruminations on SICP that started with this [http://www.billthelizard.com/2009/10/sicp-challenge.html 2009 blog entry]
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/ MIT OpenCourseWare SICP class] with video lectures
* [http://www-formal.stanford.edu/jmc/recursive.html RECURSIVE FUNCTIONS OF SYMBOLIC EXPRESSIONS AND THEIR COMPUTATION BY MACHINE] The paper that started it all, describing the theory behind LISP.
* [http://www.utdallas.edu/~gupta/courses/apl/lambda.pdf A Tutorial Introduction to the Lambda Calculus] by Ra�ul Rojas

[[Category:Classes]]

Schemers

2012-07-15T18:41:47Z

Obscurerichard: /* Exercise Solutions */

HacDC is hosting a biweekly study group dedicated to mastering the fabled computer science text, [http://mitpress.mit.edu/sicp/ Structure and Interpretation of Computer Programs], by Harold Abelson and Gerald Jay Sussman, with Julie Sussman. This text is now available for free under a [http://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. We began in May, 2012 and plan to continue this session until we finish the book.

== Logistics ==

Anyone is welcome to attend, normally the meetings are held in person at the [http://www.hacdc.org/location/ HacDC space], in the classroom area, although if that is booked, we may meet in the sanctuary.

=== Meetup Group ===

We keep the master calendar on [http://www.meetup.com/hac-dc/events/calendar/ the HacDC meetup] calendar. Please RSVP If you plan to attend a session.
=== Mailing List ===

Students are encouraged to join the [https://groups.google.com/a/hacdc.org/forum/?fromgroups#!forum/sicp SICP mailing list] where class discussions take place between study groups.

=== Text ===

SICP comes in both print and electronic editons. Amazon sells a [http://www.amazon.com/Structure-Interpretation-Computer-Programs-Engineering/dp/0262510871 new softcover print editon] for about $33. The [http://mitpress.mit.edu/sicp/full-text/book/book.html free online HTML text] from MIT is the most complete and functional electronic version, but there's an [https://github.com/ieure/sicp epub version] ([https://github.com/downloads/ieure/sicp/sicp.epub download]) suitable for ebook readers (Kindle, iPad, etc) available also.

=== Tools ===

Any fully functioning Scheme interpreter will work. Most people in the class are using [http://racket-lang.org/download/ DrRacket] due to its excellent interactive debugger and friendly beginner environment. It's also possible to use these tools:

* [http://www.gnu.org/software/mit-scheme/ MIT Scheme], the environment the text recommends.
* [http://www.gnu.org/software/guile/ GNU Guile] (built into most Linux distributions, try "sudo apt-get guile" or "sudo yum install guile")
* [http://slidetocode.com/ Lisping], a radical new iPad Scheme and Clojure programming environment

== Exercise Solutions ==

Several study group members are posting their solutions online:

* [https://github.com/benauthor/sicp-in-sheeps-clothing Ben's solutions], including some JavaScript and Python solutions
* [https://github.com/bwestergard/sicp-exercises Bjorn's solutions]
* [https://github.com/obscurerichard/sicp-study Richard's solutions]

== Resources ==

* [http://www.billthelizard.com/ Bill the Lizard] has exercise solutions and ruminations on SICP that started with this [http://www.billthelizard.com/2009/10/sicp-challenge.html 2009 blog entry]
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/ MIT OpenCourseWare SICP class] with video lectures

[[Category:Classes]]

Schemers

2012-07-15T18:40:52Z

Obscurerichard: Add meetup link /* Logistics */

HacDC is hosting a biweekly study group dedicated to mastering the fabled computer science text, [http://mitpress.mit.edu/sicp/ Structure and Interpretation of Computer Programs], by Harold Abelson and Gerald Jay Sussman, with Julie Sussman. This text is now available for free under a [http://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. We began in May, 2012 and plan to continue this session until we finish the book.

== Logistics ==

Anyone is welcome to attend, normally the meetings are held in person at the [http://www.hacdc.org/location/ HacDC space], in the classroom area, although if that is booked, we may meet in the sanctuary.

=== Meetup Group ===

We keep the master calendar on [http://www.meetup.com/hac-dc/events/calendar/ the HacDC meetup] calendar. Please RSVP If you plan to attend a session.
=== Mailing List ===

Students are encouraged to join the [https://groups.google.com/a/hacdc.org/forum/?fromgroups#!forum/sicp SICP mailing list] where class discussions take place between study groups.

=== Text ===

SICP comes in both print and electronic editons. Amazon sells a [http://www.amazon.com/Structure-Interpretation-Computer-Programs-Engineering/dp/0262510871 new softcover print editon] for about $33. The [http://mitpress.mit.edu/sicp/full-text/book/book.html free online HTML text] from MIT is the most complete and functional electronic version, but there's an [https://github.com/ieure/sicp epub version] ([https://github.com/downloads/ieure/sicp/sicp.epub download]) suitable for ebook readers (Kindle, iPad, etc) available also.

=== Tools ===

Any fully functioning Scheme interpreter will work. Most people in the class are using [http://racket-lang.org/download/ DrRacket] due to its excellent interactive debugger and friendly beginner environment. It's also possible to use these tools:

* [http://www.gnu.org/software/mit-scheme/ MIT Scheme], the environment the text recommends.
* [http://www.gnu.org/software/guile/ GNU Guile] (built into most Linux distributions, try "sudo apt-get guile" or "sudo yum install guile")
* [http://slidetocode.com/ Lisping], a radical new iPad Scheme and Clojure programming environment

== Exercise Solutions ==

Several study group members are posting their solutions online

* [https://github.com/benauthor/sicp-in-sheeps-clothing Ben's solutions], including some JavaScript and Python solutions
* [https://github.com/bwestergard/sicp-exercises Bjorn's solutions]
* [https://github.com/obscurerichard/sicp-study Richard's solutions]

== Resources ==

* [http://www.billthelizard.com/ Bill the Lizard] has exercise solutions and ruminations on SICP that started with this [http://www.billthelizard.com/2009/10/sicp-challenge.html 2009 blog entry]
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/ MIT OpenCourseWare SICP class] with video lectures

[[Category:Classes]]

Welcome to the HacDC Wiki

2012-07-15T17:56:19Z

Obscurerichard: /* Cool Stuff Going On Right Now */ Added link to Schemers study group

[[Category:HacDC_Wiki]]

{{TOCright}}<span style="font-size:large; line-height:1.5em; color:#222">Welcome to HacDC. We are a hacker space located in Washington, DC. HacDC members improve the world by creatively rethinking technology. We break, build, and occasionally abuse technology in the pursuit of greater knowledge about how it works and repurposing it to build new things. Our shop is located in the [http://en.wikipedia.org/wiki/Columbia_Heights%2C_Washington%2C_D.C. Columbia Heights] neighborhood of DC.</span>

If you're new here, you should start by looking at our public web site at [http://www.hacdc.org/ hacdc.org]. Our Wiki is mostly for internal organization, but you're welcome to look through to get a sense of what we work on (and consider joining yourself!). We invite you to subscribe to our [https://groups.google.com/a/hacdc.org/group/Blabber/topics Blabber] public discussion mailing list.<hr>

<div style="float:left; width:48%;">
=== Cool Stuff Going On Right Now ===

* [[Byzantium]]
* [[3D Printing]]
* '''Microcontroller Mondays''' (BYO project to work on, get help on, or show off...or just come to check us out! ...usually from 7:30pm on.)
* [[Schemers|"Schemers" a Biweekly SICP study group]] meeting on [http://www.meetup.com/hac-dc/events/64832532/ alternate Tuesdays]
* '''{S,Th}oftware Thursdays''' (BYO project to work on, get help on, or show off...or just come to check us out!) ...usually from 7:30pm on.)
* [[Amateur radio]] '''Ham Radio''' - make stuff, get your license, QSO, test, tinker, learn,... 2nd and 4th Wednesdays ...usually from 7:30pm on

=== Top Links ===
Themes and threads that span across the other categories in the Wiki. This is also where we keep things that don't easily fit in other categories:

* '''[[Outline]]'''
* [[New Space]] (as of June 2010)
* [[GettingHere]]
* [[:Category:Meeting Minutes | Meeting Minutes and Agendas]]
* [[:Category:Classes | Classes]]
* [[:Category:Hacker Travel | Hacker Travel]]

=== [[:Category:Projects]] ===
Where our projects collaborate and document their research and progress. They are generally classified as:
* [[:Category:Ongoing Projects | Ongoing Projects]]
* [[:Category:Previous Projects | Previous Projects]]
* [[:Category:Proposed Projects | Proposed Projects]]

=== [[:Category:In the Space | Records]] ===
Entries relating to the space including layout and events and classes we hold
* [[:SpaceSearch | Space Search: the search for a new space]]
* [[:Category:Space Configuration | Configuration]]
* [[:Category:Event Planning | Event Planning]]
* [[:Category:Classes | Classes]]
* [[Wishlist]]
* [[:Category:What_I_Stole | What I Stole]]
* [[Human_Resources | Workspace Access]]
* [[Central_Services | HacDC Leadership]]
* [[Inventory | Inventory]]
* [[Procurement | Procurement]]
* [[Suppliers | Suppliers]]

</div>

<div style="float:right; width:48%;"> 
=== Events ===
<googlecalendar>?showTitle=0&showPrint=0&showCalendars=0&mode=AGENDA&height=250&wkst=1&bgcolor=%23FFFFFF&src=uu5p71ump3g23l2mj7cvk2l2tb7girmo%40import.calendar.google.com&color=%2328754E&ctz=America%2FNew_York" style=" border-width:0 " width="500" height="250" frameborder="0" scrolling="no"></googlecalendar>

This calendar pulls events from our official [http://www.meetup.com/hac-dc/#calendar Meetup] calendar. A [http://hacdc.org/ics iCal feed] is also available, for enjoying our events from your favorite calendaring software.

=== Past Cool Stuff That Will Happen Again ===

* [[LightningTalks]]
* [[IntrotoVisualsforProgrammers | Intro to Visuals for Programmers]]
* [[Electron Tube Class]]
* Max/MSP Workshop
* [[Quantified Self]]
* [[Intro to Programming]]
* [[AVR Microcontroller Class 2011]]
* [[Great Global Hackerspace Challenge]]
* [[Linux Class]]
* [[TECS | The Elements of Computing Systems: Building a Modern Computer from First Principles]]
* [[Bike Maintenance Class]]
* [[HacDC Spaceblimp 5]]
* [[Robotics Class 2011]]

=== [[:Category:Community]] ===
Pages on people in our community :
* [[:Category:Members | Member User Pages]]
* [[:Category:Friends | Friends of HacDC]]
* [[Heroes | Heroes and people who inspire us]]

=== [[:Category:Policy]] ===
Our Policy Manual is divided into the following subcategories:
* [[Articles_of_Incorporation|Articles of Incorporation]]
* [[Bylaws]]
* [[MIBS_Simplified_Rules_of_Coordinated_Consensus_through_Chaos | Meeting Rules]]
* [[Privacy_Policy | Privacy Policy]]
* [[Resource_Use_Policy | Resource Use Policy]]
* [[Resource_Disposal | Resource Disposal Policy]]
* [[:Category:Communications Policy | Communications Policy]]
* [[Licensing_Policy | Licensing Policy]]

</div>

Schemers

2012-07-15T17:55:06Z

Obscurerichard: Added class summary page for SICP / Schemers study group

HacDC is hosting a biweekly study group dedicated to mastering the fabled computer science text, [http://mitpress.mit.edu/sicp/ Structure and Interpretation of Computer Programs], by Harold Abelson and Gerald Jay Sussman, with Julie Sussman. This text is now available for free under a [http://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. We began in May, 2012 and plan to continue this session until we finish the book.

== Logistics ==

Anyone is welcome to attend, normally the meetings are held in person at the [http://www.hacdc.org/location/ HacDC space], in the classroom area, although if that is booked, we may meet in the sanctuary.

=== Mailing List ===

Students are encouraged to join the [https://groups.google.com/a/hacdc.org/forum/?fromgroups#!forum/sicp SICP mailing list] where class discussions take place between study groups.

=== Text ===

SICP comes in both print and electronic editons. Amazon sells a [http://www.amazon.com/Structure-Interpretation-Computer-Programs-Engineering/dp/0262510871 new softcover print editon] for about $33. The [http://mitpress.mit.edu/sicp/full-text/book/book.html free online HTML text] from MIT is the most complete and functional electronic version, but there's an [https://github.com/ieure/sicp epub version] ([https://github.com/downloads/ieure/sicp/sicp.epub download]) suitable for ebook readers (Kindle, iPad, etc) available also.

=== Tools ===

Any fully functioning Scheme interpreter will work. Most people in the class are using [http://racket-lang.org/download/ DrRacket] due to its excellent interactive debugger and friendly beginner environment. It's also possible to use these tools:

* [http://www.gnu.org/software/mit-scheme/ MIT Scheme], the environment the text recommends.
* [http://www.gnu.org/software/guile/ GNU Guile] (built into most Linux distributions, try "sudo apt-get guile" or "sudo yum install guile")
* [http://slidetocode.com/ Lisping], a radical new iPad Scheme and Clojure programming environment

== Exercise Solutions ==

Several study group members are posting their solutions online

* [https://github.com/benauthor/sicp-in-sheeps-clothing Ben's solutions], including some JavaScript and Python solutions
* [https://github.com/bwestergard/sicp-exercises Bjorn's solutions]
* [https://github.com/obscurerichard/sicp-study Richard's solutions]

== Resources ==

* [http://www.billthelizard.com/ Bill the Lizard] has exercise solutions and ruminations on SICP that started with this [http://www.billthelizard.com/2009/10/sicp-challenge.html 2009 blog entry]
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/ MIT OpenCourseWare SICP class] with video lectures

[[Category:Classes]]

Occupancy Sensor

2011-08-15T04:19:51Z

Obscurerichard: Put in link to HTML version of calendar... note that July 27 2010 is the last entry in the calendar

{{Floating TOC}}

[[Category:Ongoing Projects]] [[Category:In the Space]]

== HacDC Lab Occupancy Sensor ==

HacDC's lab occupancy sensor is now operational.

Key features include:
# Real-time and historical occupancy data is available for your projects. Perhaps a twitter bot, data visualization heat map or remote occupancy indicator?
# The underlying architecture demonstrates an approach allowing bidirectional communications between many microcontrollers and many application
# The Google Calendar "hacdcdoorman@gmail.com" is updated every five minutes with current occupancy data

== Technical Overview ==

Martin configured a sensor system consisting of an Arduino, a Radioshack photoresistor (276-1657) and a Quest passive infrared motion detector as shown in the following schematic diagram.

[[Image:OccupancySensor.png]]

This Arduino is connected to the jukebox computer via USB and monitored by a simple Python script that forwards occupancy sensor data to a Spread messaging system (see spread.org). Several "agent" applications receive occupancy status messages via Spread and perform tasks such as updating a Google Calendar and data logging.

All software developed as part of this project is GPLed and available via LaunchPad at: https://launchpad.net/hacdcoccupancy

A demonstration agent is also included in the distribution, providing a convenient starting point for your projects. This demo agent currently toggles LEDs in my house based on HacDC lab occupancy status.

== [https://www.google.com/calendar/embed?src=hacdcdoorman%40gmail.com&ctz=America/New_York HacDC Doorman Google Calendar] ==
<include iframe src="//www.google.com/calendar/embed?mode=WEEK&height=600&wkst=1&bgcolor=%23FFFFFF&src=hacdcdoorman%40gmail.com&color=%23A32929&ctz=America%2FNew_York" style=" border-width:0 " width="800" height="600" frameborder="0" scrolling="no"></iframe>

Electron Tube Class

2011-08-15T04:15:29Z

Obscurerichard: spelling nitpick

== About ==

Some people have made the mistake of expressing interest in electron tubes. They're about to learn more than they bargained for.

== News ==

The first session was a great success. We covered the first item in the syllabus and part of the second.

The next session will feature a brief review of the first session and finish covering the second section. I think it should be possible to reach the section on advanced circuits. during the next session.

I also owe you guys a tube dissection, I'll try to work that into the next session too.

== Schedule ==

Next class: Aug 11 at 7:30 PM.

== Silly Bus ==

* Thermionic emission: From the lightbulb to the pentode.
* Fundamental circuits and coupling
* Push-pull and Phase splitting circuits
* Transformers in single-ended and push-pull.
* Advanced circuits
* Tube failure modes

* Hands-on experience building a battery-powered single tube filamentary pentode pre-amp.

* Power supplies and tweaking.

* What is the real secret to great sound?

=== Laboratory Supplies ===

[http://www.bottlehead.com/store.php?crn=220&rn=438&action=show_detail cheap demo pre-amp]

Go to [tubedata.info] and obtain what you think is the most informative datasheet for the following tubes and print out a copy. -- you need a physical copy.

'''filamentary diode'''
5U4*
Optional: GZ34 / 5AR4

'''canonical triode'''
2A3
Optional: 845

'''to explore gain versus output'''
6SN7*
6SL7* or 12AX7 / ECC83

'''Pentodes'''
6BQ5 / EL84
Optional: KT88, EF86

3S4 <<< absolutely required, this is the tube we're using.

=== Suggested Reading ===

Radiotron Designer's Handbook 4th ed. [www.pmillett.com] Might have one lying around.

Tube Circuits for Audio Amplifiers (1-882580-03-6) features some very elegant and practical designs.

An Approach To Audio Frequency Amplifier Design. (1-882580-05-2) Has some good discussions about output transformers and ultralinear design. Then it starts out with some nice practical amps but, before long at all, starts talking about 1,100 watt monsters with 2.5KV power supplies.

Building Valve Amplifiers (0-7506-5695-6) is probably too practical to be enjoyable but I have to deem it essential. His other book is fantastic, one of the most well worn tomes in my personal library, but get this one first.