Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: woolysheep on July 24, 2008, 08:51:10 AM

Title: Types of Photoresistors
Post by: woolysheep on July 24, 2008, 08:51:10 AM

Hi,

One last question for now about the $50 robot. 

I am getting some photoresistors from digikey and am wondering what resistance I should get.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1967023;keywords=photocell (http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1967023;keywords=photocell)

I have no idea what is ideal and if someone could explain how to know/decide and then just tell me which ones to get it would be greatly appreciated (explanation so that I can learn how to choose).

Thanks.

Title: Re: Types of Photoresistors
Post by: pomprocker on July 24, 2008, 10:04:28 AM

Basically admin was saying to go to a Radio Shack and buy the 5 pack of CDS photoresisters, and use the two mid sized ones. Then you take a multimeter and measure in the lightest room its going to be in, and the darkest room its going to be in. Then you do the math on the photoresister tutorial page, and that will give you what resistor value to buy.

Title: Re: Types of Photoresistors
Post by: bulkhead on July 24, 2008, 05:26:38 PM

The resistance range doesn't matter too much because you can always add resistors in series/parallel to get it to the range you need.

If you can buy them locally at Radioshack because with digikey, if you don't know exactly what you want you may get something strange and unusable.

Title: Re: Types of Photoresistors
Post by: woolysheep on July 26, 2008, 06:58:49 AM

ok thanks, I live in Canada though so there is no radioshack and they don't ship to Canada.  We have the Source instead but it sometimes doesn't carry everything radioshack does, photoresistors included.

Title: Re: Types of Photoresistors
Post by: Admin on July 30, 2008, 09:32:31 PM

Any of those resistances will work fine.