Picture of Learning to program a arduino - photoCell
Robot undercontact.JPG
Hi there! Today I will be talking about using a photocell with programming, But first we have to Bread board all the components into the right places.  do so like the photo below, or buy the Photocell kit from Aarons Robotics and read the manual in the package.


Here is what

How do Photocells Work?!

That is a very good question, Photocell consists of two special pieces of silicon joined together.
Pure silicon is naturally charged but if small amount of an impurity such as phosphorus is added, there are more free electron which make this a better conductor than pure silicon.
This is known as n-type(negative) silicon.
If a different impurity, such as boron, is added there is an absence of free electron. The absence of an electron is known as a hole and the silicon is known as p-type silicon.
When these two types of silicon are placed together it is called a p-n junction. An electric field is created between the two layers.
Sunlight is made up of a tiny packets of energy called photons. When photons are absorbed the energy causes electron to become free. They move to the negative layer and leave the junction to flow in an external circuit.

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thanks for the arduino tutorial, I think i'd be helpful if you talked a little more about what the code in step one does, maybe upload a video
A.R. (author)  amandaghassaei2 years ago
Ok, well I can edit the code a little cuz after any // means I'm talking about what that line in the code does. hope this help i could also post this up there to tell them I'm trying to tell what part does what. I do not have a desk top camcorder.