DEVELOPMENT OF A MICROCONTROLLER-BASED MILLIGRAM WEIGHING SYSTEM

Abstract

The research work developed a microcontroller-based milligram weighing system using a single point load cell. Load cells are generally force measurement devices that forms part of the safety system of industrial processes and also part of the quality control. The developed system utilizes a 0-100g load cell having a load pan with all the weight on it centered at a single point on the load cell. The load cell reacts to the force applied and the voltage difference from bridge sensor will be applied into the instrumentation amplifier, (AMP04) and into Analog-to-Digital Converter (ADC) ADS1220 which amplifies and convert the signal into a digital form for the microcontroller. The output is displayed on a Liquid Crystal Display (LCD). The load pan is enclosed in a near vacuum space to prevent an external influence of air on the object being measured. It was calibrated using standard mass placed on the measuring pan and the displayed values recorded. The system was examined, it was found to have percentage error of ±1.3%, standard deviation of 2.1 and when the value is greater than 60g it has percentage error of ±2.1%. The system can be adopted for measurements in chemical laboratories.