- Arduino (of course!) a Atmega328 type is best - we always recommend going with an official 'classic' Arduino such as the Uno.
- Adafruit data logger shield - assembled
- SD card formatted for FAT and tested using our example sketch
- CdS photocell and a matching 10K pulldown resistor
- Temperature sensor with analog out, such as TMP36
- Battery pack such as a 6-AA 'brick' and a 2.1mm DC jack.
- or you can use a 9V clip for a power supply but a 9V powered logger will last only a couple hours so we suggest 6xAA's
- Some 22 AWG wire, soldering iron, solder, etc.
We'll use two basic sensors to log data, a CdS photocell to track light (this will tell us when the door has been opened) and a semiconductor temperature sensor to log the ambient fridge temperature.
We have two great tutorials for these sensors on our site, if you haven't used them before or need some refreshment, please read them now!
We will wire the sensors as shown in the diagram below.
Note that we connect ARef, the power pin of the temp sensor, and the light sensor to 3.3V not to 5.0V - we do this because the 5V line is very noisy and the 3.3V regulator is better filtered. In the actual board we used the 3.3V line from the datalogger's regulator, see the images below - in theory its the same as the one off of the Arduino but we trust ours more.