watchitbanner.jpg (13140 bytes)

Home to Robert's site

nav.jpg (33387 bytes)
Up one page

It's about time
Maurice Boyer
Bulova  Accutron
The Chronograph
The Rolex Explorer
Metric time
Facts and Figures
The LED watch
Marks on the Movement
Watches in detail
Books about watches



Get your advertisement on Watch It

Click Here to become a ValueClick Host Site

In Association with
Last modified: 10 sep 2003

Quartz watches with Light Emitting Diode display [LED]

Two types of quartz watches without moving parts will be described. In this paragraph: Watches with a light emitting diode or LED display. In the next paragraph: Watches with a liquid crystal display or LCD. All these watches use a quartz crystal as a time-base, a binary frequency-divider, no stepping motor and no hands but an integrated circuit (the display driver), which composes a visible time indication on the display. In 1976, Hughes Aircraft Co. was the world's largest producer of LED modules with 1.5 million pieces.

A light emitting diode is a semiconductor diode. The dimensions are from 0.3 to 1 mm. The time is displayed by pushing the crown of the watch. The electrical current will start to flow through the diode and while the electrons stream from the N-area into the P-area, some of these electrons will "fall" into the holes of the P-area. This process is called recombination. The energy which is released this way, will be converted into warmth or light, depending on the composure of the diode. For instance a combination of 40 % gallium phosphide and 60 % gallium arsenide on a gallium arsenide substrate will result in a bright red light. Normally the display will contain four digits of seven segments each. Each segment consists of four or five light emitting diodes. Because the electrical current consumption of these watches ranges from 10 mA, without display, to 10 mA in the dark and 100 mA in full light, the two batteries need to be replaced twice a year. This is the main reason the production stopped within a few years after first release. From that time the Liquid Crystal Display watch (LCD) with an energy consumption during display a few thousand times lower than that of a LED watch, started to dominate the market for at least the following 15 years.

Hamilton Pulsar


On May 6th, the Hamilton Watch Company, Lancaster Pennsylvania USA,shows the international press prototypes of the first fully electronic wristwatch in the world: the Pulsar Time Computer. It becomes the first watch in the world without any moving parts. M. Thiess was the most important instigator for the development of this watch. The electronic module was produced by Electro Data Incorporation, Garland Texas USA and by RACES. The LED displays originated from Litronix, the reed relays from HamlinUSA and the red crystal from Corning Glass, New York USA. The case of the prototypes had been designed by the sculptor Ernest Trove of St. Louis. The watch has a calendar with programmed length of the month.This prototype of the Pulsar had 40 different integrated circuits and a battery of 4,5 V which had to be recharged every six months. Often publications can be found with an illustration of a LED watch with the name "Hamilton" above the crystal. These are prototypes. Only watches with the name "Pulsar" came into production. At the moment the press conference was given, Hamilton only had three working prototypes of the Pulsar.


The production starts with a limited series in 18 carat gold at a price of US $ 1500. The Pulsars go on sale just before Christmas.


The normal production of steel and goldfilled models starts in August 1972.Moving parts had now been eliminated and the total number of the parts was only 18, including the batteries. The first models (movement 101, 102and 401) have a magnetic setting and one button on the right. The magnet is stored in the clip of the bracelet. In order to set the hours, a magnet needs to be placed on the letters "HR" at the back of the watch. To set the minutes, the magnet needs to be placed at the spot marked "MIN".The later models could easily be adjusted by pushing the buttons once,twice or three times. Movements no. 401 and 4000, sold from 1974, have another special feature; the auto command system. When you move your arm with a very brisk and swift motion, the watch will display the time for1.25 seconds. The result of this sharp movement is that a drop of mercury in a   small sealed glass tube makes electrical contact between the two metal wire ends at one end of the tube. The case of the Pulsar is hermetically closed. The buttons contain magnets which can close a contact by means of a  reed-relay. Three photo-electric cells measure the light intensity and adapt the  brightness of the LEDs to diminish the expenditure of energy.Many famous personalities possessed a Pulsar: Roger Moore (James Bond in the film "Live and Let Die"), Leonid Brezjnef, Haili Selassie, Sammie Davisand the Shah of Iran.


The first ladies' watches are sold.The first auto command Pulsar watches are marketed in July of this year.During the first four years after its release, 50,000 Pulsars are sold.


On January 1st the Pulsar Time Computer is given a different name land from then on only sold under the brand name "Omega Time Computer".


The prices of LED watches are reduced due to overproduction in Hong Kong and Taiwan. Production stops when Hamilton loses approximately six million dollars on the entire operation, goes into bankruptcy and splits up.

There is a rare ladies' watch of which the LED display will light up at the slightest touch of a fingertip. No button to push. Unknown date of release. Eventually the LED modules by Pulsar were used by only three companies: Omega (Time Computer), Hamilton (QCT) and Wittnauer (Polara Quartz Digital).

The numbers of the movements for men's watches are: 102, 104, 401, 402, 403, 406, 4000 and 4302. The ladies' movements are identified by the following reference numbers: 101 and 4300. The Pulsar Time Computer Calculator and the Pulsar Pulse Time Computer will be dealt with in the section "Multifunctional Watches". The history of these watches has been covered extensively in Don Saunders" book ̉Time for Americả.


Huges Aircraft and Uranus, both used the same modules with a LED display produced by Fairchild. The patents of HMW (Hamilton Pulsar) created numerous problems, therefore a special agreement needed to be made for further continuation of production.

These modules were used by:

  1. 1973

    Elgin USA starts selling the "American Minicom", the "American" and the"Helbros Minicom" in January. The first watches, made of solid gold, were exclusively produced for Tiffany Co. (Basle Fair 1973). The module was manufactured by Uranus.

  2. 1973

    Croton Time Corporation USA releases the "Terrestrial Quartz".

  3. 1973

    The company "Micro Electronics Products" of Hughes Aircraft sells a LED watch called "Digitime".

  4. 1973

    The "Solitron" of Solitron Devices, New York, with a watchcase of solid gold,is released and immediately taken off the market again.

  5. 1973

    The "Synchronar" produced by the electronic firm Ness Time, Mountain View California, will be dealt with in the paragraph about solar watches.

Different manufacturers

  1. 1973

    The "Time Computer" of Omega, caliber 1600, is marketed in 1973 and presented for the first time by Omega at the Basle Fair of 1972. It is the same module as the Pulsar Time Computer caliber 102 with a magnetic setting. The 1601 (1972), 1602 (1974) and 1603 (1975) were soon to follow Omega's "Time Computer".

  2. 1974

    Texas Instruments introduces its own line of LED watches at the CES in Chicago. These were the first cheaper LED watches to be sold for less than US $ 100,-.

  3. 1975

    The Bulova Accuquartz Digital LED caliber 228 is presented at the Basle Fair of 1975. This movement has been applied in the the "Swissonic 2000" line.

  4. 1974

    Caliber ESA 9290 with lateral time display is introduced at the 1974 Basle Fair. The movement was sold by Jaz, France and Mido, Switzerland.

  5. 1975

    The "Quartz Crystron LED" (cal. 9002), the first LED watch to be produced by Citizen is marketed.

  6. 1976

    The production of a small ladies' caliber ESA 9370 LED starts. The modules are put to use in watches produced by, amongst others,Certina and Jaz.

  7. 1976

    The LED Touchtron produced by Orient becomes a novelty.When the watch crystal is slightly touched by a fingertip, the LED lights up.Jaz and others followed.

  8. Other early LED watch manufacturers are Ricoh Watch, Quantum, Computer Crown, Hudson Harris, New-Port, Nivada (Quartzonic) and Ledo.

  9. The first Russian LED watch to be brought on the market is the 2651.

  10. The Russian Company Tegrov sells a peculiar LED imitation watch with a red glass, a small light bulb and fluorescent numbers which give the impression of a LED display.

  11. 1976

    The "Futur" of Zenith Time S.A. is introduced at the 1976 Basle Fair. A quartz watch with caliber no. 47 or 470 to 473 equipped with hands and a small two digit LED display that indicates the date or the seconds. It also shows time indication "am" or "pm".

  12. Waltham manufactures a LED watch with a display that elevates itself and becomes visible at the touch of a button on the side of the watch.

  13. 1976

    The Nepro Quartz XJ-S watch inspired by the Jaguar XJ-S car is produced.

Copyright © 1994-1995 Pieter Doensen.