In August 1964, Longines approached Bernard Golay and Jean – Claude Berney of the company B. Golay SA in Lausanne, to discuss the possibility of developing a quartz controlled, small sized clock to submit to the Neuchâtel Observatory chronometer competition of the same year. To be validated, an entry for this competition would need to be submitted until 26.10.1964 the latest (4).
The Foreplay: Calibre L800
In only 2.5 months B. Golay SA, already specialised in microelectronics, together with Longines would present a small sized ‘pendulette’ (movement size: 48 x 64 x 56mm) to the Neuchâtel Observatory chronometer competition of 1964. In this piece, Longines’ experimental electro – mechanical movement L400 (see below) would be connected to a quartz (12KHz) controlled electronic system containing 25 miniaturised transistors, resistances and capacitors placed on two levels of electronic wafers giving birth to calibre L800 (4). This experimental prototype would then set a precision record in the category of ‘isolated pieces’ with an N-score of 0.15 (0 meaning absolute precision) and be admitted in a modified form to the Observatory competition of 1965 in the category of electronic marine chronometers where it will win in its category with an N-score of 0.05 (4). The initial L800 movement was later used for the commercialisation of a very small series of brass cased ‘pendulettes’.
After the successful demonstration of their cal.: L800 at the chronometer competitions of the Neuchâtel Observatory in 1964 (category of isolated pieces) and 1965 (category of electronic marine chronometers), Longines prolonged the collaboration with engineer Jean – Claude Berney and his team of specialists. The next step would be to miniaturise the movement and thus getting it within reach for being pocket watch sized and ultimately for being worn at the wrist.
The Missing Link
To achieve this goal Jean – Claude Berney referred again to Longines’ experimental, electromechanical calibre L400, developed from 1961 to 1963, containing an unique stepping motor, and use it as a base also for the next smaller experimental prototype series.
The team around Jean – Claude Berney would take a commercially available, glass incapsulated quartz, vibrating at 12KHz, re-think the system of calibre L800 and develop a miniaturised circuitry to break the frequency down to 2Hz in order to properly activate the stepping motor of cal.: L400. As for the construction of cal.: L800, the L400 movement itself was stripped of its battery hatch, the date mechanism and the balance wheel bridge including the balance wheel. The remaining calibre consists of the stepping motor assembly and the wheel work to move and set the hands. Latter partial movement would then be combined to the aforementioned, miniaturised, hand-soldered circuit of individual transistors (at the beginning without the use of an integrated circuit) to divide the quartz frequency from 12 KHz down to 2 Hz (1).
The stepping motor of cal.: L400 is worth mentioning, as it is an unique construction consisting of a coil rotatably arranged between the poles of a permanent magnet. With each 2Hz pulse from the quartz resonator divider chain, it is tilted by about 60 degrees. A small spring attached to it advances the central gear wheel which drives the wheel work moving the hands. Moreover, the motor seems to be identical to the one used years later in Rolex’s ‘Oysterquartz’ (cals.: 5035 and 5055) launched in 1977. Rolex’s electronics laboratory at the time had been set up by the engineer René LeCoultre (1918 – 2018). It is obvious that he did not want to ‘re-invent’ the stepping motor, but rather reverted to an already proven albeit experimental design (1).
The whole system runs with two 1.35V batteries and was integrated into a plated brass chronometer competition configured case. The serial numbers of the prototypes are derived from the respective cal.: L400 movement numbers (11.882.9xx) within. All known experimental cal.: L400 movements were made between 1961 and 1963.
Only 4 such hybrid, experimental prototypes were made in early 1966 (3). The earliest by numbering and development is presented below (P1: #11.882.932). The next one would be the one which won the chronometer competition in the category of electronic pocket chronometers at the Neuchâtel Observatory in 1966 (P2: #11.882.946) and which was in possession of Golay SA (albeit being marked ‘Longines’), but has unfortunately been lost (3). A third one is in a German private collection (P3: #11.882.948) (1). The latest piece by numbering is the second version shown below (P4: #11.882.950).
Interestingly an evolution in miniaturisation with respective miniaturisation and reduction in number of components can be observed when comparing the details of the first (P1: #11.882.932) with the last (P4: #11.882.950) version: The number of individual transistors decreases, some transistors get smaller, a primitive integrated circuit is added and even the encapsulation of the quartz is optimised, by abandoning the fragile glass tube and suspending the quartz bar inside a custom made brass cylinder. When comparing the dimensions, the custom made brass cylinder impresses with its smaller size as compared to the original, commercial glass housing.
These experimental prototypes represent the very last phase before the miniaturisation of major components, the development of specific, appropriate motors and batteries which later allowed for the construction of wrist watch sized quartz movements. The speed in miniaturisation of quartz controlled systems during these few years of the mid 1960s is impressive and these two movements certainly represent one most important missing link between experimental miniaturisation of the quartz system for industrial and professional application and applied miniaturisation for the wrist.
By observing these two prototypes (P1 vs. P4) alone, one can contemplate the aforementioned rapid, concise and targeted miniaturisation finally culminating in the development of cal.: L6512 which will emerge 3 years later as a prototype and which in 1971 will be mounted by Longines into the commercialised watch model known as ‘Ultra Quartz’.
Longines L400 – Hybrid – P1, Experimental Prototype, 1966
Prototype category: experimental proof of concept
Description: plated brass cased (chronometer competition configuration) experimental electromechanical – quartz – hybrid movement. Lid attached to the case by 4 screws. Eccentrically located aperture for the dial, covered with a flat acrylic crystal. Movement number (= cal. L400 prototype serial number) engraved in one corner of the lid. Case with 4 holes to accept screwed lid and two holes for mounting the movement. Recess for the crown and aperture for the stem with adjacent contact plug. Construction of the movement on two, opaque green, superposed circuit board wafers (not containing integrated circuits) attached to each other with two screws. Two levels of individual transistors.
Lower level accepting two 1.35V batteries, a glass capsule containing the 12KHz quartz bar. This lower wafer is prepared to be screwed onto the plated brass case with two screws.
Upper level accepting the remaining transistors, the contacts for the positive poles of the batteries and the fragmentary cal.: L400. Latter movement fragment shows a connection with the divider chain array by means of a soldered electrical cable to the stepping motor assembly. The fragmentary L400 movement is fixed with two miniature screws to an incomplete copper ring, itself soldered to metal pins integrated into the upper wafer. The bridge holding the hand setting mechanism and the wheel work for the hands is partially cut off, it shows fragmentary engraved info ‘L400 Longines Swiss, 13 Jewels (when complete), 11.882.932’. The white coloured, brass dial is fixed to the movement with one screw at ‘minute 26’. Dial signed ‘Longines’ at ’12’. black printed minute track, remnants of ‘chronometer competition detection sticker’ at ‘6’. Plated brass hands, the tip of the second hand hand coloured in black. Anonymous brass crown.
Movement: Longines cal.: L400 electromechanical – quartz hybrid, #11.882.932 (electromechanical part made 1961 – 1963, modified and combined with quartz circuitry in early 1966)
Longines L400 – Hybrid – P4, Experimental Prototype, 1966
Prototype category: experimental proof of concept
Description: Uncased experimental electromechanical – quartz – hybrid movement. Construction of the movement on two, opaque brown, superposed circuit board wafers attached to each other with two screws. Two levels of individual transistors (some smaller, less in number and in slightly different configuration as compared to P1).
Lower level accepting two 1.35V batteries, a custom made brass tube containing the 12KHz quartz bar. This lower wafer is prepared to be screwed onto a plated brass case with two screws.
Upper level accepting the remaining transistors (slightly less and in different configuration as compared to P1), a black, square, primitive integrated circuit replacing some transistors, the contacts for the positive poles of the batteries and the fragmentary cal.: L400. Latter movement fragment shows a connection with the divider chain array by means of a soldered electrical cable to the stepping motor assembly. The fragmentary L400 movement is fixed with two miniature screws to an incomplete copper ring, itself soldered to metal pins integrated into the upper wafer. The bridge holding the hand setting mechanism and the wheel work for the hands is partially cut off, it shows fragmentary engraved info ‘L400 Longines Swiss, 13 Jewels (when complete), 11.882.950’. The white coloured, brass dial is fixed to the movement with one screw at ‘minute 26’. Dial unsigned. Black printed 5 minute track and minute dots, intact ‘chronometer competition detection sticker’ at ‘6’. Plated brass hands, the tip of the second hand hand coloured in black. Anonymous brass crown.
Dimensions: movement overall: 44 x 44 x 12.3mm
Movement: Longines cal.: L400 electromechanical – quartz hybrid, #11.882.950 (electromechanical part made 1961 – 1963, modified and combined with quartz circuitry in early 1966)
Additional Info: following the explanations above, these pieces are the base for the development of Longines’ ‘Ultra-Quartz’ model finally launched in 1971 and pertinent ‘partial’ prototypes for the Rolex ‘Oysterquartz’ models of 1977.
Albeit some pieces are clearly marked with the ‘Longines’ name and the winner of the chronometer competition in the category of electronic pocket sized watches in 1966 (P2: #11.882.946) being clearly and repeatedly marked as such for the press photos, all four pieces were exclusively made at the Golay facilities and remained in possession of B. Golay SA until bankruptcy in 1974 (3).
Upon inquiry at Longines Heritage service, they were not aware of the existence of these pieces and no trace of them can be found in their archives, which seems understandable, as all pieces were completely made at Golay’s facility and remained there after the competitions. Unfortunately no written records of their development, or whereabouts survived (3).
The tips of the second hands are hand coloured in black to enable the detection of their passage in front of the chronometer detection sticker at ‘6’. As the second hand passes by, the narrow, white line on the sticker is covered by the second hand and a photo-sensitive detector registers its passage, repeatedly measures the time until the next ‘covering of the white line on the sticker’ and compares it with the reference clock at the observatory to determine the precision of the movement (3).
One astounding fact concerning the development of the Swiss wrist watch sized quartz movement is, that the procedure of miniaturisation was successfully advancing simultaneously in collaborating institutions (CEH) and singular manufacturers independent of each other: In early 1966 B. Golay SA was on the verge of getting the quartz system almost small enough for the wrist, whereas during the same period Dr. A. Frei, senior engineer at the CEH, managed to develop an electronically controlled quartz module of only 27mm in size setting the first mark for the following wrist sized quartz revolution.
The custom made brass cylinder for housing the quartz bar of #11.882.950 might be the earliest known successful Swiss attempt of custom adaptation and miniaturisation of the quartz element. As the quartz bar would need to be placed inside a ‘vacuum chamber’, to avoid energy loss due to friction with air, the technical defeat was enormous. Not only the container was required to be air tight, but the means to remove the air from the container and seal it afterwards needed to be developed (3).
Please refer to the parent section for further historical info and the context during which these experimental prototypes were created.
- Linder P.; Au Coeur d’une Vocation Industrielle: Les mouvements de montre de la maison Longines (1832-2009) Tradition, savoir-faire, innovation, Edition de Longines 2010, courtesy of Longines’ Heritage Service
- Personal communication with a senior engineer directly involved in the prototype developments and construction at B. Golay SA from 1965 to 1974 (he constructed the circuitry himself for the 4 experimental L400 – Hybrid prototypes).
- Journal Longines, March 1965, courtesy of Longines’ Heritage Service