perhaps another post on the temperature sensor LM335A but I cannot figure it out. I connected the LM335A sensor to arduino, as I have seen on many posts, with 2 resistors of 1K (don't have a single 2K). The returned values ??are plausible (I do not need the highest accuracy). I wanted to connect a LED on the digital port 7 (for example) in order to have it turn when certain temperature is reached. I realized that by connecting the LED, the value reported by the sensor rises instantly from about 25 degrees to almost 36 (I mean Celsius - I made a conversion from Kelvin in the sketch). Why is that? In my real, final project, in place of the LED at I will insert a relay which activates a fan, once exceeded 40° C in a small room but I cannot figure how to deal with this variation. I figured that adding a LED I need to decrease the resistor... but how much (even if it was correct)?
You have advice for me on this? Thank you!