Project: A Cheap, Accurate Thermometer

Discussion in 'The Completed Projects Collection' started by tracecom, Mar 5, 2011.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
    This is a simple little project that results in a useful tool: an accurate thermometer with a remote wired sensor. The thermometer is accurate and very inexpensive.

    The project is easy, safe, and suitable for electronics beginners. I previously posted about it on this forum, but did not provide full instructions. After some encouragement, I wrote a detailed procedure, which is attached.

    Note that even though the instructions are for a Farenheit thermometer, it could just as easily be built in a Celsius version by substituting an LM35DZ for the LM34DZ.
    Last edited: Mar 7, 2011
    Metalmann likes this.
  2. Georacer


    Nov 25, 2009
    Good one! The accuracy is 0.5 degree Celsius as per the datasheet, pretty adequate!
    Other useful applications can also be found in it.
  3. someonesdad

    Senior Member

    Jul 7, 2009
    Nice job! I hope it becomes a sticky.
  4. calvinsmit

    New Member

    Sep 8, 2010
    I am using this idea as water temp sensor in my Low pressure solar geyser on the roof. Because of the long cable run you HAVE to put a 2k-10k in series of the output leg at the sensor.Compensation for cable run. Also I leave the meter on the milivolt scale and have a 3pole double throw switch on top.When I push it I get my reading.Using one battery for meter and sensor !! A 1000uf cap charges all the time across the battery, untill I push the button and then the battery gets switched to the meter and the cap switched to supply power to the sersor. Wait 1 sec to stabatilze and bingo..