OpenCircuits - User contributions [en]

POV display

2007-11-17T19:26:51Z

Tifair: spam deleted

== POV display ==

A "persistence of vision display" (POV display) has only a single line of LEDs blinking on and off.
The display mechanically sweeps it across a person's field of view,
giving the illusion of a 2D display.

''(Do I need a diagram or a picture here?)''

(Nearly all LED displays in microwave ovens and alarm clocks electrically sweep the digits across a person's field of view, giving the illusion that it's displaying all 4 digits of the time "12:55" when actually only one digit is illuminated at any one instant).

[[User:DavidCary]] is building yet another "POV display".

I plan on putting a few features into my display that I haven't seen in any other so far:

* bright blue LEDs (even though blue is usually the most expensive color ... although sometimes "true green" is even more expensive than blue).
* no slip rings -- just pumping energy across an air gap
* ... and a few other features that I'm keeping hush-hush.

I want lots of lumens.
Unfortunately, when I go to pick LEDs out of the catalogs, they're not
rated in lumens, they're rated in candelas.

Is it even possible to estimate "lumens" from the catalog information?

Do you know what the difference is? Does your flashlight really
produce 10 times the light ( in lumens)? Or does the flashlight merely
focus its light on a tiny spot, so that that spot gets 10 times as
many candelas ?

For example, check out these 2 LEDs:
$8.75 SSP-LX6144C7UC : 4000 mcd at 120 mA
$8.75 SSP-LX6144D7UC : 1800 mcd at 120 mA

From the mcd rating, it appears that the first one is more than 2wice
as bright -- and it is, if you're directly in front of it when you
look at it.
However, if you're even the tiniest bit off-center, the second one is
much brighter -- in fact, the total lumens that second LED puts out
(2500 mlm) is slightly more than the total lumens than the first one.
If you diffuse the light and try to light up a whole room with an
array of them, the second one will make the room brighter.

I'm currently planning on using these in my first POV display:
* $1.32 Telux TLWB7900 : blue : 330 mlm, 231 mcd at 50 mA. (price in ones from http://Newark.com/ )

Other LEDs I considered using in my POV display (and may re-consider for my next one):

* $18.89 "Lamina light engine" BL-22B1-0140 : 22000 mlm at 420 mA. (this price includes the required heat sink -- price in ones from http://Digikey.com/ ). This has the most lumens per dollar I've found so far (for blu
1000
e LEDs).
* $8.750 Sunbrite LuxLEDs SSP-LX6144D7UC blue: 120 mA, 2500 mlm, 1800 mcd (Odd that the red Sunbrite LuxLEDs are cheaper at Newark, the other colors cheaper at Digikey.) cheapest $/lumen blue LED, except for the "light engine"
* $2.550 Lumex "DSP LED" 67-1876-ND: blue, 5 mm, 2500 mcd ( DigiKey ) apparently have some kind of internal chip. All colors run at 2.0 V nominal (1.5 V minimum) (rather than running on current like most LEDs. unfortunately, the data sheet doesn't suggest how much current they take -- I presume more than 20 mA).
* $1.600 Sunbrite "based LED" SSP-01TWB7UWB12 (441-1007-ND) blue 10 mm 20 mA 7000 mcd
* $5.980 GM5WA06270A SMT RGB (35 mA red, 35 mA green, 35 mA blue) 3000 mcd (full color range -- apparently used for digital
1000
camera flash ?) (Digikey)
* Mouser: hi-power LEDs ( http://www.mouser.com/search/refine.aspx?Ntt=LEDs hi-power ) shows "lumens" directly -- exactly what I wanted.

== further reading ==
Spoke-POV and propeller clocks links:

* An entire discussion forum devoted to POV displays http://www.ladyada.net.nyud.net:8090/forums/viewforum.php?f=11
** In particular, lots of nice pictures http://www.ladyada.net.nyud.net:8090/forums/viewtopic.php?p=4712
** 'no-microcontroller-programmer-needed' minipov http://www.ladyada.net.nyud.net:8090/forums/viewtopic.php?t=32
* LEDtoy on Sourceforge http://ledtoy.sourceforge.net/
* Ian’s Spoke POV http://www.ianpaterson.org/projects/spokepov20050704/index.htm
* "Propeller Clock" Mechanically Scanned LED Clock: by Bob Blick http://www.bobblick.com/techref/projects/propclock/propclock.html (I think this is the original POV display)
* micro POV display http://positron.org/projects/mpov/ small enough for "glueing it to my shaved head."
* [http://www.rickard.gunee.com/projects/mechscan/dualpic/gamesys.php "Virtual Game System - A game console with a mechanically scanned display."] can play [http://www.rickard.gunee.com/projects/mechscan/dualpic/tetris.php Virtual Tetris] by Rickard Gunée.

----

Is this http://led-display-and-design-swicki.eurekster.com/ relevant?

I think so--[[User:71.234.233.163|71.234.233.163]] 18:06, 22 June 2007 (PDT)

Fermenter Controller

2007-11-17T18:57:20Z

Tifair: spam deleted

===Project Scope===
Description: My [[http://mec-symonds.eng.monash.edu.au/cgi-bin/twiki/view/Saqqara/Md420 Md420]] fermenter controller belongs to the [[http://mec-symonds.eng.monash.edu.au/cgi-bin/twiki/view/Saqqara/PyPicn PyPicn]] family of projects. 
The PIC 18F252 microcontroller unit controls a refrigeration assisted cooling system and heaters to maintain the fermentation cabinet temperature. External, internal and vessel temperatures are measured and logged. The temperatures where I live vary greatly and as the cabinet is an old gutted fridge sitting outside it its exposed to the elements and therefore requires a decent heating/cooling setup. 
The cabinets air can be circulated using a fan driven exhaust system. This prevents gas build up, stops temperature layers forming and can be used to aid the heating/cooling system by comparing the set point with outside temperature. Fermentation is exothermic, especially so when your fermenting substances other than beer ;) Sucking in the cool night air is a very good, non power hungry, way of cooling. 
The (GTK)gui and software is written in python and works on windows and Linux alike. It talks to the PC's serial port using TCP sockets thus allowing multiple connections to the one device.
* For example. One python script is used to collect data, temperatures etc and log/ display graphs.
** A second script simultaneously requests data and can re configure if required the control features.
** A third can collect data for a web page. etc etc
* some [[http://mec-symonds.eng.monash.edu.au/cgi-bin/twiki/view/Saqqara/PicViewSnaps screenshots]] which reminds me they need updating.
* Its by no means a simple solution.
Remote access to the data and control aspects can of course be reached thru an ssh tunnel via the internet.
----

==Extension==
*The [[http://mec-symonds.eng.monash.edu.au/cgi-bin/twiki/view/Saqqara/PyPicn PyPicn]]system can and is used to control all manner of Home automation and other devices across the web or locally. Various "black boxes" like the fermentation [[http://mec-symonds.eng.monash.edu.au/cgi-bin/twiki/view/Saqqara/Md420 Md420]] collect and control various devices.
*** Its an extension of a work related project
----

===Online Demo===
You can visit the web page of a similar project.
* [[http://mec-symonds.eng.monash.edu.au/c
1000
gi-bin/twiki/view/Saqqara/RoomMonitor Room Monitor]]

[[Category:Projects]]

TRAXMOD

2007-11-17T18:16:26Z

Tifair: spam deleted

=== TRAXMOD Digital Audio Player ===
TRAXMOD is an open source digital audio player for dsPIC/ARM microcontrollers. Unlike most portable audio players, TRAXMOD's main focus is module music files (MOD, etc).

[http://www.k9spud.com/traxmod/ http://www.k9spud.com/traxmod/] - Project web site.

[[Category:Projects]]

== About Module Music ==

MOD music started in the 1980's on Amiga computers and has been evolving ever since. While MP3 seems to take center stage for most people today, module music files still provide some unique advantages over MP3:

* A huge amount of legal, freely downloadable music is available on the Internet from sites such as the [http://www.modarchive.com/ MOD Archive] and [http://www.scenemusic.net/in.htm?id=5324 Nectarine Demoscene Radio]. Most MP3 files are ripped from commercial RIAA controlled music CDs, which makes it illegal to share them with friends. In contrast, most MOD files are composed by individuals who allow them to be freely distributed.

* MP3 files are finalized raw wave data that are not easy to tinker with. MOD files combine individual instrument wave data and note event information (ala MIDI) which allows users to see more information about how the music is composed. It is far easier to read, remix, and tinker with MOD music files for those learning about creating music.

* Numerous free and low cost programs exist to support the creation of new module music on most platforms. Many people create MOD music in their home with minimal equipment, rather than spending large amounts for studio time.

* Small file sizes, usually even smaller than MP3 files of comparable play length.

* Patent free.