Simple power supply circuit and test power supply

The present invention is applicable to the field of power and provides a simple power supply circuit and a test power supply which are used for converting the alternating current provided by an AC power supply into direct current and outputting the direct current to a DC load. The simple power supply circuit comprises a transformer whose primary coil is connected to the live line and zero line of the AC power supply, an AC and DC conversion module which is connected to the secondary coil of the transformer to convert the alternating current outputted by the transformer into direct current and output the direct current, and a voltage adjustment module. The positive input end and the negative input end of the voltage adjustment module are correspondingly connected to the positive output end and the negative output end of the AC and DC conversion module, and the positive output end and the negative output end of the voltage adjustment module are correspondingly connected to the DC load and the ground so as to adjust the voltage of the direct current and output the direct current to the DC load. According to the simple power supply circuit and the test power supply, the AC and DC conversion can be realized only through the transformer, the AC and DC conversion module and the voltage adjustment module, the structure is simple, the cost is low, and the simple power supply circuit and the test power supply are easy to realize and widely promote.