The hardware is quite simple. At first here is a list of all you need
|5||Sharp IS471f||IR light beam||3€|
Luckily you will be able to use the most expensive parts (no. 1-5) from above again for quite a lot of other exciting projects.
Let us begin with the power supply. To use longer cables to the bird box it’s a good idea to use a higher voltage (7-12V, e.g.) for the long cable and transfer that voltage to 5V in the bird box.
Initially I tried a 7805 voltage regulator but that became quite hot. Because of that a switching mode power supply is the better choice. I were lucky to find them at our local electronics super market for about 7 euros. One week later they were sold for 11… The one I found is an USB adapter which can be used in a car’s cigarette lighter connector. If you have enough place in your bird box you might even use it’s USB plug and connect the Raspberry Pi via it’s Micro USB connector. My bird box does not have that much place in it so I had to solder two connectors to the power supply and connect it to the PiFace. Bear in mind that you skip the Raspberry’s fuse by that.
IR Light Beam
To detect a bird coming into the bird box a IR light beam is used. There is a good IC (Sharp IS471 f) that controls an IR led on it’s own and detects the light beam or in our case if the light beam is broken.
Place the sensor on one side of the bird box’s hole and the LED on the other side. If you like connect it to the PiFace’s output 7 if you want to be able to disable the light beam. It’s not a need but it might be a good idea to disable the light beam while taking a photo. But you may as well connect it (pin 3) to the ground directly.
The light which falls though the hole is quite a lot, but its better to have some additional lights in the house. I will give it a try with three IR LEDs which will be enabled while taking a photo.
In my first draft I planned to use ten LEDs, but that’s too much for my new small house, so let’s hope that the sun is always shining or take some more LEDs if you have the place for them. If you use more of them, it might be a good idea to place them in series. But keep in mind that you’ll need a different resistor then. If you place more LEDs in parallel you’ll need to check the resistors power dissipation.
Sharp IS 471