If you want to have centralized up to 8 locations temperature readings - you should consider building this temperature logger. Design is really simple as it used up to 8 1-wire buss temperature sensors DS1820.

Temperature sensor device is interfaced with LCD panel which is able to display up to 2 temperature values. It also has a separate DS1302 Real Time Clock (RTC) module with over 3 months backup. It also supports Wayne’s NTP format for updating the clock to a Time server. If you need to monitor more than two temperatures then you need to connect device to PC via Serial port. Any terminal software can be used for this. Full project files are available for download here.

Do you like to feel acceleration while driving a car? There is a way to see that force in numbers.

Great thing is that accelerometers are really cheap and small today. They come in small IC packages that can be easily integrated in to embedded devices. In order to interface ADXL320 accelerometer you need a microcontroller with analog input. This circuit uses a PIC18F452 which reads an accelerometer data and displays F-force on three 7 segment LED displays. G-Force meter is a real straight forward sensor which read and outputs data directly to display.  Program is written in C language for C18 compiler. It can be great addition to you car or anywhere where you feel acceleration.

Alberto ricci bitti has a nice collection of amazing projects in his website. One of his designs is scriptable thermometer which can be programmed in basic like language within built in editor.

Design circuit is very simple four buttons, four relays, RS232 interface and graphical LCD connected to 8 bit COP8CCR9 microcontroller from National Semiconductors.

Scriptable controller has 6kB non volatile memory where custom scripts can be stored and executed. Built in ASCII interpreter can run scripts as custom applications. Author even provides two examples of scripts that can be run instantly. One of them runs controller as graphical thermometer while another as GSM cell phone connected vending machine. This design also was awarded as application of the day in national Semiconductors.

This simple four channel temperature meter can be connected directly to your computer COM port and doesn’t require additional power supply. Check you computer back if there are any com ports before you start.

Temperature meter is based on ATtiny15L microcontroller which has built in ADC. Power for this circuit is taken from com port ER and RS signal lines. High level of these lines is from 6 to 12V and can supply up to 5mA of current. As L series microcontrollers are low power this is more than enough.

As temperature sensors there are four 103AT thermisters used. They give pretty good precision at room temperature (~0.3Cº). Author provides firmware for ATtiny15L and VBA project that logs temperature data to excel file.

Frequency counters are very popular and easy to build projects. This one is a AT90S8515 microcontroller and Lattice ispLSI2032 PLD based frequency counter. While microcontroller mainly takes care of communicating and data display, PLD counts incoming pulses and scales them down because of hardware 36bit counter implemented. When counter counts up - it generates an interrupt for MCU.

Frequency counter has 5 operating modes:

• Mode 0: Frequency(IN-1), up to 2.4GHz (in resolution of 100Hz);
• Mode 1: Frequency(IN-2), up to 100MHz (in resolution of 1Hz);
• Mode 2: Frequency(IN-2), up to 10kHz (in resolution of 100µHz);
• Mode 3: Pulse Period(IN-2), up to 10sec (in resolution of 100nsec);
• Mode 4: Pulse Width(IN-2) up to 10sec (in resolution of 100nsec)

And have three dedicated inputs for various cases:

• IN-1: ZIN = 50ohm, 10MHz-2.4GHz;
• IN-2(AC): ZIN = 1Mohm, 10Hz-100MHz;
• IN-2(TTL): DC-100MHz

Frequency counter also has ability to communicate with PC via serial port. This way counter can log data to computer or be simply controlled by computer. Project files and source codes are available for download in project page.