The LM35 of National Semiconductors that is used in this project is a precision centigrade temperature sensor, which has an analog output voltage. It has a range of -55ºC to +150ºC and a accuracy of ±0.5ºC . The output voltage is 10mV/ºC . The output voltage is converted by the AD convertor of the ATMega8. The temperature is displayed on an LCD module. In this example the thermometer has a range of 0ºC to 40ºC and a resolution of 0.5ºC. If you want to have a readout in Fahrenheit you can use the LM34.
LM35 Based Thermometer Display Temperature on LCD: [Link]
At this thermometer, the IC thermo sensor (S8100) or the diode (1S1588) is used as the thermo sensor. When using the IC thermo sensor, the thermometry to +100°C from -40°C is possible. Also, when using the diode, the measurement to +150°C from -20°C is possible. Both sensors are contained in the kit.
LCD Thermometer With Range From -20 to +150°C: [Link]
It’s a good idea to use LCD’s with projects like this instead of led digits, because LCD’s don’t need to be refreshed, they allow you to display many characters and it requires less I/O pins. In this project a 16×1 LCD Display with 4-bits interface it’s used. Time and date are displayed as HH:MM:SSx mmm dd, where: HH = Hours MM = Minutes SS = Seconds x = AM/PM mmm = Month (Jan, Feb, Mar) dd = Day.
LCD Display with Date and Time: [Link]
If you’re looking for a build-it-yourself, standalone, USB harddrive based MP3 player, this may be of interest to you. Originally conceived as a replacement for a CD player, this unit sits on the shelf next to your stereo and connects via standard RCA line-out audio connectors. Features of the player include:
- Large, back-lit LCD display
- IR remote-control receiver port
- USB 2.0 connection for fast song transfers
- Functions as a USB harddisk
- 24-bit stereo audio out
- Support for fixed & variable bitrate MP3 files to 320 kbps
- Supports harddisks up to 137 GB
This is an open-source project. Full hardware schematics and software source code are freely available on the project site.
Hard-disk Based MP3 Player With USB 2.0 capability: [Link]
This project explains how you can build a very powerful wattmeter by using a simple circuit called AD8307. The author choose to make this wattmeter digital and the display showing the power in watts. A good wattmeter is very important for a hobbyist that is working with RF and transmitters, it will really make your work easier.
30 W Digital Wattmeter With LCD: [Link]
