Mahfoozur Rehman

Development of a low cost optical tilt sensor

The paper deals with the theory, design, fabrication and test results of a Fiber optic tilt sensor. The sensor is based upon the modulation of light intensity with the change in the level of Mercury (Hg) surface with tilt. 650 nm light-emitting diode (LED) is used as light source and the reflected light is detected by light dependant resistor (LDR). The output of the receiver circuit is directly proportional to the tilt angle. The sensitivity of the two probe sensor is 0.013 V mrad−1 and the maximum range covered is 53.4 mrad. The sources of error and their minimization have been discussed.

AC magnetization characteristics for soft magnetic materials using LabView

This paper presents the design and prototyping of low-cost analog circuitry to characterize the ac magnetization profile of soft magnetic materials. Soft magnetic materials prepared as ring cores are wound with equal number of turns for the primary and secondary windings. The primary winding is excited with sinusoidal supply of varying voltage amplitude. The secondary winding is interfaced with the LabView for data acquisition and calculation. Graphical plotting and viewing of the hysteresis loop exhibited by the soft magnetic materials under test can be achieved using National Instrument NI6009 data acquisition card and LabView software. This paper discusses the methods of measurement for flux density, magnetic field intensity and core permeability.

A Microprocessor-Based Novel Instrument for Temperature and Thermal Conductivity Measurements

This article presents the details of design and development of a mobile and low-cost measuring device that can directly measure the thermal conductivity of a material. The device does not need an AC power source and needs only a battery to operate. In its operation, the output of a platinum resistance thermometer (PT100 sensor) is amplified by LM324 Quad differential input operational amplifier and fed to Microchip PIC16F877A microcontroller through an analog-to-digital converter. The microcontroller calculates the thermal conductivity of the material by a given set of temperature difference and finally the result is displayed on a liquid crystal display. PIC Basic programming language is used to program the PIC microcontroller. The analog circuit and printed circuit board layout are designed using OrCAD software. It has been observed that the proposed device can measure the temperature with an accuracy of 0.5°C and thermal conductivity with an accuracy of 0.01 W/mm °C. The power consumption of the device is found to be 277.25 mW.

A simple capacitive security card system

A simple and reliable capacitive security card system is designed, fabricated and tested. It consists of capacitive card reader system, an integrator, rectifying circuit, an 8051 microcontroller and LED indicators. Initially rectangular patterns of different lengths are being recognized successfully. The patterns on the security card are scanned with a thin conducting plate, which is the part of the reading system, when card is inserted in the reading system. The variations in the heights of the patterns are being converted into voltages with the help of an integrator. Output of the integrator, after rectification, is converted to digital form and fed to the microcontroller. These data are compared with the data stored in the memory of the microcontroller. The designed system is capable of recognizing up to five columns (patterns) in a single row with a maximum number of 99999.

A low cost capacitive security card system

A low cost and reliable capacitive security card system is designed, fabricated and tested. It consists of capacitive card reader system, an integrator, rectifying circuit, an 8051 microcontroller and LED indicators. Initially rectangular patterns of different lengths are being recognized successfully with a success rate of 100%. The patterns on the security card are scanned with a thin conducting plate, which is the part of the reading system, when card is inserted in the reading system. The variations in the heights of the patterns are being converted into voltages with the help of an integrator. Output of the integrator, after rectification, is fed to the ADC of the microcontroller. It is converted into numbers by it and compared with the number stored in the memory of the microcontroller. The designed system is capable of recognizing up to five columns (patterns) in a single row with a maximum number of 99999.

Ultrasonic technique for the measurement of pressure below atmospheric pressure

This paper deals with the theory, fabrication and test results of an ultrasonic technique which is used to measure vacuum in a container. Ultrasonic transmitter and receiver, working at 40 KHz, are used for conducting the experiments. The sensitivity of measurement is a function of applied voltage to the transmitter. Results on a prototype model are included and relationship between output voltage and pressure is appreciably linear.