Power supply control circuit, method and system, water outlet device and load circuit

The embodiment of the invention discloses a power supply control circuit, method and system, a water outlet device and a load circuit, and the circuit comprises a voltage regulation circuit which is used for receiving an AC voltage generated by a hydroelectric generator, and adjusting the size of the AC voltage according to a PWM signal outputted by a single-chip microcomputer to obtain a first AC voltage; the power supply output circuit is configured to perform preset processing on the first voltage to obtain a direct-current second voltage and output the second voltage to the voltage detection circuit; stabilizing the second voltage at the working voltage required by the electric device; the voltage detection circuit is set to detect a second voltage and output the second voltage to the single-chip microcomputer; and the single-chip microcomputer is set to compare the second voltage with a preset voltage threshold value and determine whether to output a PWM signal for adjusting the magnitude of the AC volta