The first LED (light-emitting-diode) digital wristwatches appeared around 1972, when an inventor named Roger W. Riehl produced an all-electric watch with no moving parts. Called the Synchronar, the watch featured red LEDs and utilized solar panels to power the timepiece’s NiCad battery. The first Synchronars cost $1,700, but by the end of the decade the price had dropped to about $130.
Around the same time, Hamilton Watch Company launched the "Pulsar-P1." These 18k gold units had an original price tag of $2,100—for some collectors they remain the Holy Grail of vintage LED wristwatches since only the 30 or so examples are known to exist. More widely available are the Pulsar P2s, famously worn by Roger Moore in the 1973 James Bond movie, “Live and Let Die.”
Other vintage LED wristwatches favored by collectors are calculator watches. These include the 1977 Pulsar 3822 and the 1977 Hewlett-Packard HP-01. Models with green displays are also rare.
Even though they were considered state of the art at the time, LED wristwatches had their drawbacks—they drew a lot of power, which caused some manufactures to make models that forced the wearer to hold a button down in order to see the time. For this reason and others, LEDs were largely replaced by more efficient, always-on LCD (liquid-crystal-diode) displays in the mid-1970s—Texas Instruments mass-produced one model for only $20.