Night vision
The standard Raspberry Pi camera is great for taking daytime snaps of people walking up the garden path, but when it comes to night time shots, it's not really suitable. There are two ways of dealing with this: the first is to illuminate the capture area with a bright light when the PIR detector is triggered, and the second is to use the Raspberry Pi NoIR camera module and an infra-red LED array to let the camera see in the dark. More about that in a minute.
The Raspberry Pi NoIR camera module; it looks similar to the standard model
An illuminating experience
In order to switch on a light or LED array from the Raspberry Pi GPIO or our port expander circuit, we need something that will allow us to drive higher currents and voltages than can be provided by the GPIO ports alone.
A good candidate for this is the TIP120 Darlington transistor, which will allow us to switch on and off loads of up to 80V and 5 A from our GPIO pins. In our full system later on, we're going to use Port B...
