This is a finished "Headphone Output to Line Input Step-Up Transformer Kit" from Akizuki Denshi. This is a finished product made by putting the Akizuki Denshi kit into a compact case. I made it myself to use in my car, but I no longer need it, so I'm selling it. When connecting the headphone output of a smartphone or portable music player to the line input of a car stereo or component system, the volume is lower compared to other sources like a CD player. This kit is useful when you need to adjust the volume. The reason for this is that the voltage of the headphone output is lower than the voltage required by the line input. This amplifier uses a transformer to step up the voltage by about 10 times, reducing the difference in volume compared to other sources. If the volume is too loud, you can use it in reverse, using the output as input, to step down the volume to about 1/10. By not using a power source such as batteries or an AC adapter, there's no need to worry about batteries, and wiring is easier. The input and output grounds are isolated, which helps prevent noise caused by the grounds of connected devices being connected. It is also effective for (ground loop isolator) applications such as car audio, where it is necessary to cut off ground loops. The left jack is the input, and the right jack is the output. ■ Main Specifications ・ Transformer used: AT403-2 ・ Input/Output Terminals: 3.5mm stereo mini-jack (compatible stereo mini-plug) ・ External Dimensions: 50mm x 25mm x 50mm AT403-2 Headphone Output to Line Input Step-Up Transformer Kit https://share.google/rOY6mkGvJrp55e10p # Akihabara # Akizuki Denshi