Updated rctime and temperature info

Yianie

Hello, I am very new and I sure this is a very old question, but I would like the most up to date info. I would like to use the RCTIME to measure temperature. Assuming that the prefered way of wiring is used, what thermistor and capacitor did you use? I may measure the temperature from a distance of 10ft. I am also assumming calibrating reading to actual temperature is a must. Thank you...

erco

YMMV; that is to say, yours will be a custom situation and you can make many different RC combinations work for you. What temp range are you measuring, room temp? Freezer temp? Thermistors come in all shapes & sizes. If you have a decent electronics store, see if they have any thermistors. If there is a choice, pick one with a higher resistance value (1000 ohms or more) which gives the most % resistance change over the temp range you expect. Once you get a thermistor, you can experiment with cap values (or come back here & ask, once you have a range of sensor resistances). You'll do a custom calibration once you get all your wiring in place.

BTW, there are more modern one-wire and I2C sensors that can output digital temperature directly, but those are trickier to use:
http://www.ebay.com/itm/Dallas-DS18B20-DS1820-Digital-Output-Temperature-Sensor-/120928023718?pt=LH_DefaultDomain_0&hash=item1c27df34a6

Here's a premade thermometer with a 10-foot cable: http://www.ebay.com/itm/Indoor-outdoor-thermometer-Taylor-Digital-Temp-with-Alarm-Clock-Model-1408-/330743907415?pt=LH_DefaultDomain_0&hash=item4d01df8457

But DIY rules. Nothing wrong with using a thermistor, and RCtime, it's a great learning experience and a rite of passage IMHO. A thermistor can be quite accurate when calibrated properly.

stephenwagner

http://www.parallax.com/Portals/0/Downloads/appnt/stamps/bs1Appnotes.pdf

Try this link. It is for the stamp 1. However, the math and tricks apply to the stamp 2. You can even use MS Exel. to write the equation. Or create the equation from the thermister data sheet.

SJW

stephenwagner

Page 33 of the PDF file, Page 103 of the manual.

SJW