How can i make a DIY cheat, small tracking device?
I want to make a tracking device that could potentially connect to a smartphone. I don't need it to do that many things. I want the device to understand borders, and when my phone leave that device for a certain (custom) distance. My phone should receive some sort of alert . Most likely i am going to make this device a sticker device, so i want it to be flat, or almost flat, and as thin as possible . I want this device to use very little energy, so i battery could last a very , very long time. Also i don't want the device to be too costly, ( if possible 5-10 dollar for one ) Also, if i would to add gps feature , what module should i use, and would it increase the size by a lot? Thank you in advance.