Design of a Portable and Low-Cost Power Supply for Laboratory Projects Using the Switch-Mode Method

Abstract

Ghana is growing increasingly concerned about regular power outages. This issue occasionally impacts laboratory research, practical work, and experimentation. Additionally, it hinders research projects and students' academic advancement. The purpose of this project is to design and construct a dual power supply for laboratory instruments which uses a 12V battery as the source of input energy. This project consists of a combination of set-up circuit, double-ended Push-Pull (dc-ac) and Boost (dc-dc) converter with switching element made up of bipolar transistors are switched 'on' and 'off using PWM controller CD4047 with switching frequencies of 50 Hz and 1 KHz.The converter operates from a 12V battery providing output power at 250 V (2A) AC and 12V (2A) DC. A double-ended Push-Pull converter receives energy from the input source when the switch is 'on' and then pumps energy into the primary windings of the transformer. Energy flows from the input winding to the transformer output winding when the switch is 'off. The isolation transformer converts the de-input to AC output. Boost converter is a de-de converter, designed without a transformer or inductor; it allows the output voltage to be greater than the input voltage. The method is similar to that of a double-ended Push-Pull converter. The developed dual power supply, no-load AC output produces 250 volts with zero current and 237 V- 238 V, on-load with a current of 0. 18 A to 0.19 A respectively depending on the load. The de-de converter output produced values from 0-12V for the input of 8V to 12V. The power supply that has been developed is highly beneficial for domestic, laboratory, and research purposes.