hamster
Posts: 23
Joined: Fri Sep 23, 2011 10:20 pm

Re: An example of where this project may help Education in the Pacific

Mon Nov 07, 2011 3:40 am

Have a read of this article:

http://pacific.scoop.co.nz/2011/11/your ... -treasure/

\"A University of Canterbury/Rotary International-led development project aiming to bring power and technological capacity to Tongan high schools faces just one obstacle before its pilot phase can start.Your IT trash could be someone’s treasure\"

A complete system based around new parts using a RaspPi must be possible for about US$150 using common wholesale.component.

- Raspberry Pi B Board $35 (in a case, when available).
- Monitor 19\" with built-in speakers $70
- HDMI->DVI cable $6
- Budget Keyboard + Mouse $15,
- SDHC card $8,
- $8 share of the networking ($80 for a 16 port switch+ cable)
- \"Zap Catcher\" with USB charge ports

It would also be much more serviceable than a pile of old PCs running on a tropical island, and a lot of the bulk and weight will be gone. bulk storage could be on an Ethernet connected disk or low end NAS.

I think the power side of the equation would also be of benefit greatly too - Each terminal would use under 25W per terminal (monitor is rated at 18W, a Pi can be no more than 5W), compared with a cheap desktop + old monitor (maybe 100W at idle). For a classroom of 10 systems the power budget comes down to around 300W rather than 1000W... freeing up 700W that can be used on other things.

wallabybob
Posts: 17
Joined: Thu Aug 18, 2011 2:08 am

Re: An example of where this project may help Education in the Pacific

Tue Nov 08, 2011 3:49 am

[quote]For a classroom of 10 systems the power budget comes down to around 300W rather than 1000W... freeing up 700W that can be used on other things.[/quote]
Or reduce the number of solar panels required.

I\'m doing similar considerations for a number of locations in the Solomon Islands.

At http://www.air-stream.org.au/LM2576 there is a circuit and veroboard layout for a simple switchmode voltage regulator capable of converting 12V to 5V and delivering 3A which should be capable of driving a few Pis and a few USB devices.

hamster
Posts: 23
Joined: Fri Sep 23, 2011 10:20 pm

Re: An example of where this project may help Education in the Pacific

Tue Nov 08, 2011 8:15 am

That circuit is nice and easy, but I would be tempted to use something like http://www.dealextreme.com/p/100w-car-d ... port-91344 which would give you power for the monitor as well...

What sort software are you looking at providing? Education? Productivity apps? Web access?

wallabybob
Posts: 17
Joined: Thu Aug 18, 2011 2:08 am

Re: An example of where this project may help Education in the Pacific

Wed Nov 09, 2011 1:02 pm

Some TVs have HDMI inputs and will accept 12V power. We\'re planning to use LEDs for lighting so will probably be able to avoid any mains voltage and associated losses in inverters.

I working with a couple of friends who have been to the first site (I haven\'t). There is no mains electricity and telco internet is very expensive. I am thinking of using RaspberryPis as thin clients to a server which holds imported non-copyright books, and audio and video forms of lectures. I\'m thinking a lot of material could be downloaded by friends in Australia or New Zealand. Also want students to be able to learn basic word processing, computer text searches and email.

kme
Posts: 448
Joined: Sun Sep 04, 2011 9:37 am

Re: An example of where this project may help Education in the Pacific

Wed Nov 09, 2011 1:28 pm

[quote]Quote from wallabybob on November 9, 2011, 13:02
We\'re planning to use LEDs for lighting so will probably be able to avoid any mains voltage and associated losses in inverters.[/quote] Inverters are very efficient, 95+ percent. Routing 12 or 5 V around easily generates bigger losses - Ohm\'s law is unmerciful. Unless everything can be reach within 10-20 m from the solar panels low voltage DC is a no-go. Add to this all mass produced (hence cheap) things expects 230/110 V. Going 12 or 5 V and you will have to make a lot of adaptions yourself and that\'s expensive. Staying with mains voltage allows you to use existing infrastructure.

Warringer
Posts: 56
Joined: Tue Aug 23, 2011 5:04 pm

Re: An example of where this project may help Education in the Pacific

Wed Nov 09, 2011 7:14 pm

[quote]Quote from hamster on November 7, 2011, 03:40Bulk storage could be on an Ethernet connected disk or low end NAS.
[/quote]
Throw in another Pi and a USB harddrive and you got a simple NAS. With the added possibility of using it as a web server for \'cloud storage\'.

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