Switch power supply reactive circuit with large output voltage and adjustable output voltage range

The utility model provides a switch power supply reactive circuit with a large output voltage and an adjustable output voltage range, and relates to the technical field of electric. The switch power supply reactive circuit comprises an error amplifier UC3842, a first pin and a second pin of an inverted input terminal of the error amplifier UC3842 are connected in parallel and grounded, and a fourth pin of an input terminal of the error amplifier UC3842 is connected with an adjustable resistor RT and a current transformer CT in parallel; the other terminal of the adjustable resistor RT is connected with an eight pin of the error amplifier UC3842, and the fourth pin of the error amplifier UC3842 is connected with a field effect transistor Q1; one terminal of the field effect transistor Q1 is grounded, and the other terminal of the current transformer CT is connected with an output terminal of the field effect transistor Q1; and under the stable input voltage condition, the duty ratio of a drive pulse is invariant, and the pulse frequency is decided by the oscillation frequency of four-pin RT/CT (the adjustable resistor/the current transformer). By adopting the switch power supply reactive circuit with the large output voltage and the adjustable output voltage range, the power supply can stably work, and vibration caused by overlarge duty ratio of a switch tube can be avoided, wherein the overlarge duty ratio is caused by an overlarge adjustable output voltage range.