Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: wlc on January 21, 2008, 07:17:29 PM

Title: $50 robot/photoresistors
Post by: wlc on January 21, 2008, 07:17:29 PM

Instead of purchasing the photoresistors from radioshack, I'd like to purchase them from Digikey with the rest of my purchase.  I tried locating some myself, but there are so many options with so many specs. Does anyone know of a digikey part# that would work great for this?

Thanks

Title: Re: $50 robot/photoresistors
Post by: Admin on January 24, 2008, 03:23:32 PM

do a search for:
photocell
phototransistor
CdS

Title: Re: $50 robot/photoresistors
Post by: Trumpkin on January 24, 2008, 07:33:38 PM

I don't think the values matters too much (someone please correct me if i'm wrong). here is a link to digikey photoresistors  http://search.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch . If you have a radio shack next to you I highly reccomend you just get them there. Sorry I couldn't help you more!

Title: Re: $50 robot/photoresistors
Post by: SmAsH on January 24, 2008, 07:59:07 PM

yea value doesnt affect it much. but generally if i use more than one i get the same size for all.

~smash

Title: Re: $50 robot/photoresistors
Post by: airman00 on January 24, 2008, 08:15:15 PM

Quote from: SmAsH on January 24, 2008, 07:59:07 PM

yea value doesnt affect it much. but generally if i use more than one i get the same size for all.

~smash

yes it does !!!

a 1 M ohm photoresistor and a 10K photoresistor require different software code and also teh comparator , comparing input, would also have to be changed

Title: Re: $50 robot/photoresistors
Post by: Admin on January 24, 2008, 08:25:14 PM

It matters in what your second resistor value is, and the time response (time it takes to change with light). For a photovore, I wouldn't worry about the value . . .

Title: Re: $50 robot/photoresistors
Post by: airman00 on January 24, 2008, 09:09:18 PM

Quote from: Admin on January 24, 2008, 08:25:14 PM

It matters in what your second resistor value is, and the time response (time it takes to change with light). For a photovore, I wouldn't worry about the value . . .

true but if you use a POT procedure (internal capacitor discharge i think) to measure resistance without a second resistor ( like you would have in ADC), then it matters

Title: Re: $50 robot/photoresistors
Post by: Trumpkin on January 30, 2008, 04:05:04 PM

but this is for the $50 robot. It doesn't matter for this.