ABSTRACT

Yuniarti, Virtual Instrument (supervised by Zahir Zainuddin and Rhiza S. Sadjad).

This is a design project to develop a virtual instrument which is basically a computer simulation of an instrumentation system. The main characteristics of various physical sensors are stored in a library of files accessible by the simulation program. The program performs a virtual electronic circuit to display digitally the measurement of a physical parameter performed by a sensor.

The electronic circuit simulation consists of an amplifier functioning as a buffer circuit of the sensor, an equalizer, an Analog to Digital Converter (A/DC), a microprocessor and a digital display. The buffer circuit is necessary for typical sensors to avoid loading effect due to impedance mismatch or high output impedance. The equalizer provides 0 to 5 Volt input for the A/DC as specified. The A/DC output is digital data to be computed by the microprocessor to display the physical parameter.

Three types of sensors are considered as examples in this research, namely: (1) a Carbon Monoxide (CO) gas sensor TGS5042 measuring 0 to 1000 ppm of gas, (2) moisture sensors HIH-3610 (measuring 0 to 100% relative humidity) and H23K5A (measuring 10 to 90% relative humidity) and (3) a thermistor 36K53A1(D1) measuring -30oC to 100oC of temperature.