“This project came about because I bought a capacitor kit with mainly X7R (good quality) capacitors, but some of the higher values 100nF and above were the cheaper and less stable Y5V dielectric, which exhibit a massive change over temperature and operating voltage. I wouldnt normally use Y5V in a product Im designing, so I tried to find alternative uses for them rather than let them sit on the shelf forever.
I wanted to see if the temperature change could be exploited to make a useful and very low cost sensor, and as you’ll see over the next few pages it was quite simple, with only one other component required.”