The invention discloses a small transformer, which comprises a support seat, a connection groove is arranged on the upper surface of the support seat, and a damping rotating shaft is connected in the connecting groove, the outer key of the damping rotating shaft is connected with a turntable, and the turntable is fixed There are blocks attached. The clamping block is engaged on the groove, and the groove is arranged at the corner of the connecting ring, the connecting ring is fixedly connected to the lower surface of the outer cover, and the outer cover is nested with a cover ring. The small transformer can easily adjust the ratio of the number of turns of the first coil and the second coil, so that the small transformer can be applied to a variety of situations, and avoids the traditional small transformer due to the number of turns of the first coil and the second coil. The ratio of the number is constant, which makes its use restrictive, and it can be easily disassembled and installed, so that it can be easily repaired and repaired, avoiding the small transformers in the past, which were fixed with bolts, which caused the bolts to corrode after long-term use. Inconvenient disassembly and installation problems.