--- On Fri, 9/21/12, Kevin Mark <kevin.m...@verizon.net> wrote:
From: Kevin Mark <kevin.m...@verizon.net>
Subject: Re: [support-gang] What Sensors and Where To Buy?
To: "support-g...@laptop.org" <support-g...@laptop.org>, "IAEP SugarLabs"
<iaep@lists.sugarlabs.org>, "OLPC SoCal" <olpc-so...@laptop.org>, "Community
Support Volunteers -- who help respond to help AT laptop.org"
<support-g...@lists.laptop.org>
Date: Friday, September 21, 2012, 2:55 AM
--- On Thu, 9/20/12, Caryl Bigenho <cbige...@hotmail.com> wrote:
From: Caryl Bigenho <cbige...@hotmail.com>
Subject: [support-gang] What Sensors and Where To Buy?
To: "support-g...@laptop.org" <support-g...@laptop.org>, "IAEP SugarLabs"
<iaep@lists.sugarlabs.org>, "OLPC SoCal" <olpc-so...@laptop.org>
Date: Thursday, September 20, 2012, 8:37 PM
Hi…
OK, here I am again with another "dumb" question… well, maybe not so dumb after
all as I'll bet there are others out there who could also use this information.
On the OLPC wiki there are several very nicely illustrated instructions about
how to make sensors to use with the XO… temperature, humidity, light, etc.
But, they don't include a materials list or reference to sources where the
parts can be purchased.
http://wiki.laptop.org/go/Making_XO_sensors
Radio Shack? Edmond Scientific? Parallax.com? or where? Curious people, myself
included want to know. Can someone help here?
Thanks!
Caryl (GrannieB)
P.S. Here's an example of the type of info needed. This site sells a number of
light sensors but they call them things like Photoresistor, Photo Transistor,
Light to Frequency Converter. These are all little ones that appear similar to
the one in the instructions on the wiki. How do you tell which kind you need?
I'm not someone schooled in Electronics, just an autodidact. If you are talking
about a 'light sensor', this is usually a device that when exposed to visible
white light will change its electrical resistance. If you are familiar with the
concept of volts, current, and resistance, the basic components of Ohms Law,
this device would be part of a circuit and act as a gauge for the amount of
lightness or darkness in a room. So the device would increase its resistance
which is measured in Ohms when more light hits the active surface. if you buy
this[0] at Radio Shack, it will contain various types of these cells. The main
difference is their resistance range. Some might vary the resistance from 0 to
1,000 Ohms, some might vary from 0 to 10,000 Ohms. Or other response ranges.
The names can vary. I first knew them as a Cadmium Sulfate Cell, they can also
Light Dependent resistors. Or Photoresisitors.
As for the light to frequency converter, that is a different device.For the
sake of experimentation and convience, the radioshack package might be an OK $4
investment. If you know someone who likes electronics, they might have these
parts to space. Even better if you can visit a 'hackerspace' where they can
help with a few parts and explanation.
I think the main use is to connect the light sensor directly to the audio-in
port of the XO, which means a few wires, an audio jack and the light sensor.
The 'Measure' Activity should provide a basic idea of how the sensor reacts to
varying amounts of light.
[0] https://www.radioshack.com/product/index.jsp?productId=2062590
This is a minor update because I was reading a post[1] on sparkfun. This kit
shows a kit with single examples of various types of sensors. This kit is too
expensive but you can buy the individual parts separately at their site or
elsewhere.
[1] https://www.sparkfun.com/products/11283-k
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