The Yamaha TC-66 is a vintage cassette deck manufactured by Yamaha in the 1970s. It is a compact and portable cassette recorder/player that was popular for personal use and voice recording. It featured a built-in microphone, line-in and line-out jacks, and a single-speed motor for playback and recording. The TC-66 had manual controls for recording level, bias adjustment, and tape type selection. It operated on batteries or with an external power adapter.