Hello everyone,

I'm currently working on a project to build a digital thermometer but i don't have a clue on how.

What I need is to design a digital thermometer that can measure the current ambient temperature in a building, which will show the maximum and minimum temperatures detected.

The thermometer must be battery powered with the readings being refreshed in every two seconds. The maximum and minimum temperatures should be automatically re-set at midnight.

Please could you help?
Thank you

 

One way is to start with an LM35 - http://www.national.com/mpf/LM/LM34.html - and collect temp readings with a microcontroller. What resources do you have?

 

You can also use an LM334 as a temperature sensor. There are several application hints in Texas Instrument's datasheet.

Your project would be simplified considerably if you used a microcontroller such as a PIC, a Basic Stamp, or the like that had a built-in ADC (Analog to Digital Converter). Otherwise, you would need to build an ADC circuit, design a logic circuit to get the current reading, compare the reading to the highest and lowest so far observed, keep track of time, etc etc. Rather involved.

 

As another approach, you could use a DS18B20 together with an AVR ATTINY2313 to handle the 1-wire interface to the temperature sensor and a couple or three 7-segment LED displays to displays play the temperature.

Of course, if you are not interested in getting involved in learning to write your own programs you are probably better off following beenthere's approach.

hgmjr