HomeVision Light Sensor Project
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Creating a simple light sensor for
HomeVision |
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| Motivation/Problem: One of the common inputs you would like to have in a home automation system is a sense of how bright it is outside. While I have tried create a truly smart sunny/cloudy/day/night sensor (unsuccessfully, just having some indication of light level is useful. Solution: I use this simple circuit to do basic light level detection. It's an analog circuit which simply uses a solar cell to generate a voltage which is proportional to the amount of sunlight hitting it. A simple opamp circuit amplifies this voltage level and feeds it to one of HomeVision's analog inputs. Here's the schematic. The real trick is how do you mount the sensor? I have constructed a wooden enclosure that looks like a small bat house. The solar cell is set in epoxy on the surface of the cover which is at a 45 degree angle. I mount this on the south side of my house and run a ribbon cable through the window to a small adapter which converts the ribbon cable to an RJ45 jack for the trip back to HomeVision in the basement via CAT5 twisted pair cable.
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