The utility model discloses a single-sheet electronic adjustor circuit of an automobile. The circuit comprises a starting circuit module and a voltage reference circuit module, wherein, the starting circuit module is connected with the voltage reference circuit module and an adjusting tube module; the voltage reference circuit module is connected with an error amplifying circuit module. A sample circuit module is connected between the L terminal and the F terminal of a magnet exciting coil and is connected with the error amplifying circuit module. The error amplifying circuit module is connected with the voltage reference circuit module, the sample circuit module and the adjusting tube module. An overheat protective circuit module is connected with the adjusting tube module. An electronic switching circuit module is connected with the adjusting tube module and the error amplifying circuit module. The adjusting tube module is connected with the L terminal and the F terminal of the magnet exciting coil, the error amplifying circuit module and a fly-wheel diode module. The fly-wheel diode module is connected between the L terminal and the F terminal of the magnet exciting coil and is connected with the adjusting tube module. The utility model has the advantages of small size, small scope range of the fluctuation of voltage, high anti-counterpressure capacity, small temperature coefficient and high reliability.