One day in 2019, a few friends invited me to start the polishing service for iPod mini2 again. Taking this opportunity, I also designed and made this compact amp, which perfectly fits the needs of going out. The original fairy was intended to use the power strategy of boosting two AAA batteries, but in actual test situations, the compatibility of this circuit to boost devices is not ideal. At the same time, in order to match the endurance of the highly modified version of imod, several After the second experiment, the battery was re-locked to the lithium battery, thus creating a battery life of up to 100 hours (default op amp combination). Still not much nonsense, this amp is charged with a microusb port, and the internal switch and charging status indicator are built-in, and the charging and use modes can be manually switched to completely eliminate the sound influence of the charging line on the amp line. Regarding the circuit, the three-channel structure, a circuit full of musical taste, OP+BUF class 47 main amplifier circuit, combined with R2R op amp, achieves that the driving force is still abundant in a small size, and people know its properties at a glance. It is better than blue, so I won't repeat it here. The fairy's voice is warm and surging, the details are vivid, and the music is strong and durable. Don't underestimate its sound level because of its small body. It has high battery life, small size, and low thrust. As the name suggests, it accompanies the iPod like an elf. . Finally, report the measurements of the amp: length, width and height are about 62*48*15MM.