The invention discloses a liquid heating device with adjustable power and a
power control circuit of the device. The liquid heating device and the
power control circuit are applied to the fields of liquid heaters such as electric water boilers and electric water heaters. The power can be adjusted automatically and intelligently according to different heating stages of the device. A group of relays and a group of three-terminal bidirectional
silicon-controlled switches are connected in parallel on a circuit board, and switching and alternative use of the three-terminal bidirectional
silicon-controlled switches and the relays are intelligently controlled in the heating stages of the liquid heating device according to an embedded
chip calculation result. Therefore, when the liquid heating device operates under full power, the relays with low cost are switched to control opening and closing of a heating device. When the liquid heating device operates under low power, the three-terminal bidirectional
silicon-controlled switches with small current are switched to control opening and closing of a heating
pipe. The device achieves a power adjustable function, has high reliability, is low in cost and reduces
energy consumption by means of calculation of
software, an embedded intelligent
chip and a
control circuit, so that the liquid heating device avoids multiple boiling and effects of heavy
metal produced in the multiple boiling on health.