Design and construction of a DC – DC power supply for powering USB soldering iron

Abstract

Power supply is an electrical device that converts electric current from a source to the desired voltage, current and frequency to power an electrical load. The universal serial bus (USB) soldering iron available in the market operates on a 5-volt direct current (DC) supply. Essentially, it can be powered by any cell phone charger that is capable of providing an output power of not less than 8 watts. Absence of constant power supply from the national grid at times inhibit effective use of this soldering iron. To power it directly from storage battery is inappropriate as most batteries are rated as 2.7, 3.7, 6, and 12 volts. This paper deals with the design and construction of an inexpensive portable regulated power supply to power a USB soldering iron from a 12 volt power supply. The circuit was designed and simulated using Proteus software “intelligent schematic input system (ISIS)” before the construction procedure. Deep discharge protection that safeguard storage battery against under voltage and reverse polarity protections were added to the design. These special features distinguished it from those available in the market. Two light emitting diodes (LED) serve as indicators for low and normal condition of battery while sound from a buzzer shows that the input terminals of the circuit were wrongly connected. The system was tested and found to work as anticipated.