AUTOMATIC VOLTAGE SELECTING APPARATUS

摘要

PURPOSE: An automatic voltage selecting apparatus is provided to reduce the manufacturing cost and simplify the circuit by using simple circuit components instead of using dedicated ICs of high prices. CONSTITUTION: A rectifier(30) rectifies an AC input voltage. An output unit(40) outputs a signal of the rectifier(30) or a multiplied voltage of the signal. A triac(50) carries out the switching for outputting the multiplied voltage of the output unit(40). A comparator(60) compares a DC voltage of the rectifier(30) with a reference voltage(Vref). A driver(70) drives the triac(50) according to the output signal of the comparator(60). The DC voltage of the rectifier(30) is divided by a resistor(R1) and a resistor(R2). The reference voltage(Vref) is applied to the inverting terminal of the comparator(60).