In 1987, Casio released the TM-100, a most unusual digital watch. On the surface, it appears to be a normal time-telling model but deep inside Casio embedded circuitry to transmit audio signals. Flip the little lever above the display, raise the telescopic antenna and speak or play music into the little microphone and the TM-100 will broadcast the audio to nearby radios! A tiny tuning knob allows you to calibrate the preferred frequency on the FM band (specifically, the Japanese FM band which is 76-90MHz and a portion of the US FM band, 87.5-108MHz). The case is all plastic and it requires two batteries, one for the timekeeping feature and one for the transmitter.

To us, the TM-100 is partially shrouded in mystery. We have never seen it advertised and it is a relatively uncommon watch. The transmitter feature was never included in any other model. We know of a few gadgets sold in Japan (the birthplace of karaoke!) included a transmitter but no wristwatch. Does anyone have any information?

Make: Casio

Year of Manufacture: 1987

Model Number: TM-100

Module Number: 661

Our friend akitaishi posted a couple of very cool videos of his Casio TM-100 in action! Witness a most interesting marriage of technologies: the source is an iPod with digital audio files, playing into the Casio TM-100 and broadcast over FM into a classic ’80s boombox.