OLPC India/Khairat Technical

Khairat school, OLPC India

(draft/template)

XOs at Khairat school

Comments

1. All photos are by Carla unless otherwise stated.
2. The following are my views and may not necessarily reflect that of OLPC. For official clarifications on any of the technical aspects, please contact people at OLPC directly.

Overview of observed Bugs

The journal

Some XOs on the 613 images had their Journal gone. Image 616 fixed that bug. Once the teacher lost his files. As a result an automatic backup script was written by Amit in the site. --Carla 16:56, 30 October 2007 (EDT)

Alternative power

The power supply in town is not very reliable, so many days we didn't have power, or had it intermittently. The children tried to bring their XOs charged, but still some needed to charge them at school. --Carla 16:56, 30 October 2007 (EDT)

XOs are getting charged

Children working while charging

Cow Power Design Notes

Mechanical design prototype

Electrical design

• Referring to this ckt design http://www.zen22142.zen.co.uk/Circuits/Power/l200.html
• Also referring to design guide -http://bwir.de/download/L200_englisch.pdf
• We require Vout to be about 12V and Iout(max) to be 1A

1. For values of R2 and R1, I referred to table in right column of Page 4 of design guide. Selecting Vo=12V +-4% I get R1= 1K ohm +-1% and R2=3.3K +-1%
2. Since Isc = 0.45/Rsc (according to ckt design), I chose Rsc=0.47 ohm 1/2 watt
3. Current in R2, Ir2=(Vo-Vref)/R2 where Vref = 2.77V. Hence power dissipation in R2, Pr2 = 25.8 mW
4. Current in R1, Ir1=Vref/R1 = 2.77mA . Hence power dissipation in R1, Pr1 = 7.7 mW
5. Current thru Rsc

--Arjs 11:18, 16 November 2007 (EST)

Sharing Experience

In the classroom

Amit and I, together with the teacher and the children, did some testing on the Mesh by sharing activities. Children were working on the laptops and did different kinds of sharing to work with their classmates. The Sharing Activities wasn't that intuitive, we weren't really successful with it. Nevertheless, the children who shared activities were super-happy. --Carla 16:56, 30 October 2007 (EDT)

Comments

I was very involved with the technical side with Amit, until Manu and Arjun arrived. I still was in the loop but more involved with the educational side. So, I'll focus on the aspects that had an impact on the educational side Khairat Chronicle. We worked with the developers daily to tackle these issues. --Carla 16:56, 30 October 2007 (EDT)