Design and Development of an Embedded System for the Measurement of Boltzmann’s Constant

摘要

Objectives: In this paper we present the design and development of an embedded system for the measurement of Boltzmann’s constant using Texas Instruments’ microcontroller: MSP430G2553. Methods/ Statistical Analysis: A transistor connected in common-base configuration with collector and base maintained at the same voltage (known as diode connected transistor or Transdiode) is used as the Device Under Test (DUT). The base-emitter voltage (VBE) is varied by a stepper motorized potentiometer whose rotation is controlled by microcontroller. The collector current (IC) is measured by converting it into voltage (V) by I-to-V converter using operational amplifier. The temperature of the bath where DUT is placed is measured using LM35 temperature sensor. The base-emitter voltage VBE, collector current IC and temperature in Kelvin T are measured using MSP430G2553 microcontroller. The data is captured using terminal software PuTTY. These files are imported to the scientific graph plotting software Origin. The graphs are drawn between natural log values of IC versus VBE at ambient temperature. To perform the measurement at different temperatures a heater system with constant current source is designed and constructed in the laboratory. Findings: From the slope of ln(IC) versus VBE graph Boltzmann’s constant is calculated. The values of Boltzmann’s constant at different temperatures are averaged and compared with standard CODATA (2014) value and percentage of error is determined. Application/Improvement: Microcontroller based embedded system for the measurement of Boltzmann’s constant is rarely seen in literature. In the present work, a fully automatic electronic circuit for the estimation of Boltzmann’s constant is designed and developed. The system is built around Texas Instruments’ MSP430G2553 microcontroller and cost-effective, off-the-shelf components are used in the circuit construction.