I'm a noob just getting my feet wet in EE, so go easy on me, please. I bought an Arduino Uno and have been learning tons in the last couple weeks. I took an LM35 sensor, a generic thermistor (using a 10kohm resistor), a light-dependent resistor (photoresistor?) (using a 10k resistor), a button (using internal Arduino pullup resistor), and a couple LEDs (with 220ohm resistors), and wired them all to my Uno. I can provide a diagram, but I don't suspect that it matters much. Basically, some are sharing the same ground, and some are sharing the same 5v.
I'm noticing that the temperature data from the LM35 and the thermistor is very erratic. It varies all by itself, plus when I press the button. I've read many forum posts saying that these types of sensors need a voltage regulator to be accurate, so here's my question: Is it probable that the cause of my erratic sensor data is because the supply from my Arduino is not constant enough, and that it's sagging or spiking?
If so (or if not), what's the solution to this problem? Should I buy one of those little 5v bread-board power supplies?
And here's a graph of the LM35 readings. It's only read once every 9 seconds. It's just sitting on my office desk, no furnace vent nearby or anything. Now, the graph is not raw analog readings, but rather F temperature. But the raw analog readings are all over the map, including 116, 107, 90, 145, 129, etc. Don't get distracted by the analog->temperature math, I don't care about the accuracy, I just want it to be stable!
Update 2: The photoresistor and the thermistor are reading very consistent, only the LM35 is all over the map.