light resistors

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#1
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hi guys,
i want to incorporate a ligt resistor(s) to my robot, so when i looked informations on the web for them, what i found was that they are also called NTCs and thats all, but when i went to a radio club (serbian version of radio shack) i found that there are lots and lost of different options, like their resistance range and such,
so,
i use atmel AVR uC-s, which are the ones which would be most appropriate for basic light sensing? i thought of 0-1k range, since i used once a 1k pot to test ADC. but am unsure.
could anyone help?
thx

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'light dependent resistor' also called cadmium sulphide cell, photocell. You make a voltage divider with the LDR from ground and a regular resistor to 5V. Lets say the LDR is 20K in the light and 200K in the dark. If the regular resistor was 200K, the voltage would vary from 1/10 vcc to 1/2 vcc. Read this with the a/d converter.

Imagecraft compiler user

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It is my understanding thet NTC represents "Negative Temperature Coeficient - doesn't have anything to do with light, rather; it is temperature related.

What you may actually be looking for is called a Light Detecting Resistor (LDR).

Use an LDR in the range of about 1K - 10K Ohms in series with a 1K Ohm resistor to create a voltage divider. Depending on whether the LDR is positive or negative acting with an increase of light level, will determine whether the 1K is pulling high (VCC) or pulling low (GND).

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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sorry guys, my mistake
and thanks for answers, will go shopping first thing monday :)

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It could be the company too. NTC electronics, a company that seems to be big in the hobby industry. I recommend the Panasonic photoresistors.

Here's a google result for "photoresistor"s
http://www.acroname.com/howto/ph...

and a nice site
http://www.robotroom.com/Photoce...

Gotta love david cook's work.

an object at rest...
cannot be stopped!

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ok, i've found a LDR (emphasizing LDR, not NTC ;) which ranges from 12k to 100k
it is in a plastic case, which differences are between the glass and plastic cases (except the price)?