Photoresistor testing

pollack · 2005-05-20 13:45

i was just wondering how would you be able to test if a light·photoresistor is working using a simple circuit. all·I want to be able to do is use an LED and a couple of resistors to check if it works.

Jon Williams · 2005-05-20 13:57

Insert the photoresistor into an RCTIME circuit and test it that way. Then you'll be able to change the light and see the affect on the photoresistor. The only other parst you need are a cap (e.g., 0.01 uF) and a 220-ohm resistor. I use a smaller cap in RCTIME circuits that use photoresistors because their off resistance is so high.

Main:
· HIGH PhotoPin
· PAUSE 5
· RCTIME PhotoPin, 1, testVal
· DEBUG HOME, DEC testVal, CRLEOL
· PAUSE 100
· GOTO Main

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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Post Edited (Jon Williams) : 5/20/2005 2:16:23 PM GMT

Andy Lindsay (Parallax) · 2005-05-24 00:16

Pollack,

I would recommend looking through What's a Microcontroller.· It's available for free download from www.parallax.com·-> Downloads -> Stamps in Class Tutorials.· It has a whole bunch of activities with step-by-step instructions to help you get the hang of creating projects with the BASIC Stamp and simple circuits, including all the ones you've been asking about.·

If you're interested in building and testing the activities, most of the parts are common and easy to obtain.· Parallax also sells the parts kit in several different packages: the What's a Microcontroller Parts Kit, What's a Microcontroller Full Kit, and the BASIC Stamp Discovery Kit.· Radio Shack also has·the·What's a Microcontroller BASIC Stamp Kit in their stores.· It's a great deal, and it includes·all the parts you'd need·for all the activities along with a·project board with·built-in BASIC Stamp.

Regards, Andy

Photoresistor testing

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