Ondrej Karas of DoItWireless writes:
This article describes temperature and humidity measurement with DHT11 sensor connected to TR module. Circuit diagram is very simple. You need only power supply for sensor and one wire for data line. This line has to be “pull-uped” – sensor has open collector output.
Temperature and humidity measurement with DHT11 - [Link]
TMP75B 1.8-V Digital Temperature Sensor with Two-Wire Interface and Alert. by ti.com:
The TMP75B is an integrated digital temperature sensor with a 12-bit analog-to-digital converter (ADC) that can operate at a 1.8-V supply, and is pin and register compatible with the industry-standard LM75 and TMP75. This device is available in an SOIC-8 package and requires no external components to sense the temperature. The TMP75B is capable of reading temperatures with a resolution of 0.0625°C and is specified over a temperature range of –55°C to +125°C.
The TMP75B features SMBus and two-wire interface compatibility, and allows up to eight devices on the same bus with the SMBus overtemperature alert function. The programmable temperature limits and the ALERT pin allow the sensor to operate as a stand-alone thermostat, or an overtemperature alarm for power throttling or system shutdown.
TMP75B – 1.8V Capable Digital Temperature Sensor - [Link]
Build temperature & humidity & smoke alarm system based on ICStation Mega 2560 compatible with Arduino( Cost is USD32.39 ONLY) .
The working voltage of this system is DC5V.It can measure the current temperature, humidity and smoke. It can display real-time data by the 1602 LCD and can realize the sound and light alarm when in the dangerous temperature and humidity. It is a simply and easily to operate monitoring alarm system about temperature humidity and smoke.
Build Temperature & Humidity & Smoke Detector Alarm System Based on Arduino - [Link]
I recently stumbled across an interesting fact in the datasheet for the ATMEGA32u4, the microcontroller I am using for my Einstepper Project. I was surprised to find that Atmel had included a temperature sensor in the core of the device that you can read using the internal ADC. As it turns out, there are many megaAVR devices contain an internal temperature sensor. According to Atmel’s product finder, these devices are:
ATMEGA Core Temperature Sensor - [Link]
ICStation @ instructables.com writes:
ICStation team introduce you how to DIY this temperature & humidity & smoke alarm system based on ICStation Mega 2560 compatible with Arduino.The working voltage of this system is DC5V.It can measure the current temperature, humidity and smoke. It can display real-time data by the 1602 LCD and can realize the sound and light alarm when in the dangerous temperature and humidity. It is a simply and easily to operate monitoring alarm system about temperature humidity and smoke.
DIY Temperature & Humidity & Smoke Detector - [Link]
praveen @ circuitstoday.com posted a project on a Temperature logger using Arduino:
This project is about a simple USB temperature logging system using arduino uno and the serial monitor function in the arduino IDE. The system monitors the temperature every 2 seconds and shows it on the arduino serial monitor. The temperature is shown in °Celsius and °Fahrenheit. The system is interfaced to the PC through the USB port. LM35 is used as the temperature sensor.
LM35 is three terminal linear temperature sensor from National semiconductors. It can measure temperature from-55c to +150C. The voltage output of the LM35 increases 10mV per degree Celsius rise in temperature. LM35 can be operated from a 5V supply and the stand by current is less than 60uA. The pin out of LM35 is shown in the figure below.
Temperature logger using Arduino - [Link]
Mizchief100 @ instructables.com wanted a way to control with dorm air conditioner so he build an Arduino thermostat that controls the control knob using a servo motor:
I am currently living in a college dorm. Like most dorms it’s about the size of a tissue box but less comforting. Fortunately, my room has a heater/AC with four positions: low, medium, high, and off. Unfortunately in winter an hour on the low setting makes the room a stifling 80 degrees and when turned off it drops quickly to 60 degrees. My solution uses an arduino, temperature sensor, and motor to automatically turn the heater on/off to keep the room within a desired temperature range. Not only is this more comfortable but it dramatically reduces the time the heater is used, saving lots of energy. (Also note that the motor is only driven to switch the setting and then turned off so no holding energy is wasted.)
Arduino Thermostat (Mechanical) - [Link]
Complete digital temperature sensor Sensirion STS21 provides a top-level accuracy and stability for a very affordable price.
Digital sensor STS21 s the newest member of calibrated humidity and temperature sensors family SHT2x (SHT21, SHT25). In opposite to them, STS21 is able to measure only temperature, i.e. it´s suitable only for applications, where we don´t need to measure humidity. However a smaller functionality has also a significant positive aspect in a form of a substantially lower price. STS21 contains on a chip, similarly like its familiar, a temperature sensor, precise supply, low noise linear amplifier, AD converter and a serial interface with I2C output (fixed address different from SHT series).
Basic accuracy of STS21 in the 0 to +60°C temperature range is +-0.2°C. The user can choose a resolution for measuring and it can be 11-14 bits (up to 0,01°C). Despite the fact, that the sensor hasn´t guaranteed absolute accuracy of 0.01°C, such a high resolution can be beneficial for example for monitoring of a tendency (increasing/ decreasing) of temperature.
Detailed information can be found in the Sensirion STS21 datasheet.
STS21 measures temperature with an 0.01 °C resolution - [Link]
The MAX31730 temperature sensor monitors its own temperature and the temperatures of three external diode-connected transistors. The operating supply voltage is from 3.0V to 3.6V. Resistance cancellation compensates for high series resistance in circuit-board traces and the external thermal diode, while beta compensation corrects for temperature-measurement errors due to low-beta sensing transistors.
MAX31730 – 3-Channel Remote Temperature Sensor - [Link]
Kerry Wong writes:
In this post, I will show you yet another thermometer/hygrometer build. But instead of using an LCD or 7 segment display for the output, I decided to go retro, using two “needles” to display the temperature and humidity readings instead. And to make the project more fun, I did not use analog meters for the output but chose to use two servos instead. The temperature humidity sensor I used is SHT21 from Sensirion, the same sensor I used in my temperature logging project before. In that project, the temperature and humidity readings were sent over the network and displayed on my web server (you can see the current readings in my lab here).
A digital thermometer hygrometer with analog displays - [Link]