Well i want to make a light seeking robot. And as i saw it needs not photoresistors but CDS cells. But sadly theres none CDS cells in my country. So i was thinking can i use a simple photoresistor or not? Thanks!
A CDS is a photoresistor!
But as i read on wiki it has a difference.
This says not:-
Sorry >.> im still a newbie in all of this. And one last question. What resistance should i use for light seeking robot?
What resistance should i use for light seeking robot?
Where is this resistance?
If it is a pull up or pull down it should be the same value as the photo resistor when exposed to medium light. That is half way between the brightest and dimmest.
Grumpy_Mike:
What resistance should i use for light seeking robot?
Where is this resistance?
If it is a pull up or pull down it should be the same value as the photo resistor when exposed to medium light. That is half way between the brightest and dimmest.
Well my only choice is 8k-80k photoresistor so im asking what should be the minimum and the biggest resistance (Sorry if im saying something wrong).
(Sorry if im saying something wrong).
Well it doesn't make any sense.
8k-80k photoresistor so im asking what should be the minimum and the biggest resistance
Minimum resistance is 8K maximum is 80K but you knew that so what are you actually asking?
Im saying that my only choice to buy is 8k-80k photoresistor but on the instructions of the robot it doesnt specify what minimum or maximum the resistance should be so im asking what minimum and maximum resistance would be best for light looking robot?
what minimum and maximum resistance would be best for light looking robot?
The application doesn't matter.
What matters is the circuit you are putting it in, without knowing that you can't say.
Okay, thank you for your patience and sorry for my stupidity.
You are looking to make a voltage divider with your photo-resistor as part of the divider. As the light lever changes the voltage drop across the two resisters will change.
So if you have the divider:
+5 ----- Fixed Resistor ----- Test Point ------ Photo Resistor ------ Gnd
Play around with the fixed resistor, try 10K, 47K, 100K.
Watch the values you read from your Test Point. You will be safe to play around.
See if the value goes up or down as you vary the light. If they are going in the wrong direction, reverse the fixed and photo resistors. That will cause the values to go in the other direction. Try it and see.
Now as you write your algorithm, do you want to peek you value or dip it? They will both work but what will make your code the simplest and easiest to understand? So in your code do you want to think "the higher the number the brighter the light" or "the lower the number the lower the tracking error"?
Experiment, play around, have fun. If you don't understand what you are seeing, ask.