I have an Arduino sampling temperature(DS18B20) in my house & sending it to a web server so I can graph it. I thought it would be nice to get humidity too, so I needed a sensor. Unfortunately, I went cheap and didn't research this enough: I bought a couple of Parallax HS1101 sensors. I was expecting to just read an analog pin, do a bit of computation & be done. Instead, it looks like I need to add a 555 and ancillary circuitry, which I could do, but do I have to? Writing the code is no issue - I wrote C for a living for a while, but the electronics? That's the dark side.
However, looking at the Parallax circuit for the stamp, it looks like this thing is just a variable capacitance device affected by humidity. Can I connect it's output to an analog pin with a large pulldown on it, set an analog pin to digital out, set it high, set it back to analog read and record the decay? What of the 220 ohm resistor the Parallax circuit uses between the arduino pin & the device? I sincerely don't know enough to decide whether this is feasible so advice or abuse would be equally welcome.