The circuit seems to be very popular because it is so simple and still has a very useful and practical application and It is considered by some the perfect circuit to get started with AVR microcontrollers.
This thermometer can be used as a standalone thermometer with LCD display or it can be read out with a PC running Linux, Windows, MacOSX or solaris. BSD Unix and others are probably also possible to use for reading the temperatures. No special drivers are needed.
Simple Digital Thermometer: [Link]
The Digital thermometer was built by using the temperature sensor LM35DZ, PIC16F877 microcontroller and MAX232 IC. Temperature measurements can also be viewed on a computer program which can monitor the state of COM ports of a PC. Sample measurement data received through COM2 is being viewed on the SERIAL WATCHER program which is distributed freely on the internet.
Digital thermometer: [Link]
The brain of this project is an AT90S2313 that controls the LED Display thus showing the temperature read from a DS182 temperature sensor. The temperature sensor chip, DS1820 is connected to PD1 with a 4.7k pull-up resistor. The circuit presented here uses only one sensor, but you may tie multiple sensors on the same line and modify the program to read it with the help of internal chip ID.
ATtiny2313 Thermometer: [Link]
There are plenty of digital thermometer schematics out-there but as i said in an earlier post, its nice to have where to chose from. Being based on a tutorial about Analog to Digital conversion, it is very easy to understand the functioning of the device, and you can build it with any micro controller even if it doesn’t have a builtin ADC.
The temperature sensor used in this project is thermistor which is very suitable for measuring ambient atmospheric temperatures, but you could replace it with any other type of temperature sensor, that would function in a range that is more adequate to your application.
Digital Thermometer: [Link] - [Via]
The following project its a basic thermometer that can measure data from 2 sensors, for example you place one sensor inside the house and another one outside. The schematic is plain simple DS1621 or DS1631 digital temperature sensor and a bunch of resistors and diodes. You can use smd parts or trough-hole, it doesn’t really matter but if you want to keep things small and cool, i suggest you use smd. Also on the pcb you will solder a DB9 connector so you can stick the small pcb directly into your COM port. The measurement is than showed on the windows taskbar.
DS1621 pc thermometer: [Link]