So yesterday I talked about development boards and why they are the best thing since sliced transistors. However they are about as useful as a LED without some sort of external circuitry to attach to it. When I got my netduino I decided I would do something simple but useful, so naturally I went with a temperature sensor. this circuit also known as a shield has pins sticking down from the bottom of the PCB that fit snugly into the netduino's holes below.
My circuit would need a temperature sensor (obviously) known as a thermistor, this is because as temperature increases resistance decreases and vice versa. Next I needed some form of display, I went with 3 7 segment displays and a set of LED's. The 7 segment displays would need some form of decoding so I wouldn't need to attached all 10 pins of each display to the chip so I used the 4511 chip used for decoding a binary coded decimal to the format that will give said number on the display.
Anyway if you feel like building your own temperature shield all my plans etc. will be added at the end of the post. It works perfectly apart from one small caveat you need to add a wire attaching 3.3V on the power pins to the reference pin on J2. If you follow everything through you will end up with something like this:
Everything you need to make your own temperature shield is here:
without including the price of the PCB I would guess it could be built for under £5.