A digital thermometer is an instrument used to automatically measure the temperature of a substance or the surroundings. In this project a multiscale digital thermometer was designed. In our design there was three main parts 1. Sensor 2. Microcontroller 3. LCD display parts. A DC voltage was developed at the output of the sensor (LM35) depending on the temperature of the body to be measured. For an increase of every 1 degree centigrade of temperature an increase of 10mv voltage at the sensor output was found. We could measure the magnitude of temperature ranging from 0 to 102 degree centigrade with this thermometer and the corresponding sensor voltage output was found to be in the range of 0-1 volt. The sensor output was connected to the microcontroller input. The measured value of the temperature was displayed through an LCD display in the unit of Fahrenheit, Centigrade and Kelvin. The whole set up was mounted on a breadboard and every section of the circuit was tested individually. After getting satisfactory result every section was jointed. The response time of the thermometer was found to be of maximum 15 seconds. The total cost of the project was BDT-800/- only.

Solar radiation data are essential to the works of energy planners, engineers, environmental and agricultural scientists. But the measured radiation data for a long period are not available all over Bangladesh. However, Bangladesh Meteorological Department has been recording different climatological parameters for years together throughout the country. Computation of solar radiation may be done using these meteorological parameters. For this purpose, we used theoretical formula proposed by different authors in literature. Monthly average data on sunshine duration (n), day length (N), relative humidity (R), temperature (T) etc. for a period of 28 years between 1980 and 2007 are used. So, this study is carried out to determine empirically global, diffuse and direct solar radiation on a horizontal surface for ten districts uniformly distributed all over Bangladesh (latitude 20o34 N - 26o34 N and longitude 88o01 E - 92o41 E) as well as to predict correlations for them.

A wireless multimeter is an instrument used to measure the current, voltage, frequency and apparent power at a load from a distance. In this project a wireless multimeter was designed which consisted of two major parts: 1) Measuring Section Module and 2) Remote Display Module. Measuring Section Module consisted of three major section which are i) signal input, ii) Micro controller, iii) RF transmitter whereas the remote display module also consisted of three parts i) RF Receiver, ii) Microcontroller and iii) LCD Display Module. After all relevant calculations the dc voltage produced by the micro controller was sent through an RF Frequency transmitter module having an omnidirectional antenna. The RF receiver module situated at a maximum distance of 150 meters from the transmitter, received the transmitted data. The result is then displayed through a 16-bit LCD display module. This multimeter was found to measure the values of the voltage, current, power and frequency ranging from (0-250)V, (0-20)A, (0-5000)VA and (0-125)KHz respectively. The main attraction of our designed circuit was the simplicity of the circuit, easiness of implementation and the availability of components.

The main purpose of this project is to design an inverter that will enable the inversion of a DC power source, supplied by Photovoltaic (PV) Cells, to an AC power source that will be either used to supply a load or connected directly to the utility grid. The benefit of this project is to give access to an everlasting and pollution free source of energy. The future is looking towards alternative power sources all of which will need to be regulated in one form or another. To make this possible, a highly efficient low cost product will have to be designed. Among all the different converter designs only a few are capable of providing high power with high efficiency. This will be tested experimentally, first by computer simulation, and then in the laboratory Implementation.