In March 1952, the Elgin Watch Company announced the first battery-powered mechanical wristwatch, a laboratory prototype of what would become the Elgin Grade 725. This early electrical movement, described as the greatest advance in timekeeping in 450 years, was functionally identical to a traditional mechanical movement, minus the mainspring power source. Beat regulation was still governed by a conventional balance wheel and hairspring escapement, and accuracy was comparable to a fully mechanical movement of similar quality.
Coinciding with the development of the Elgin Grade 725 was the Hamilton 500, which would become the world's first commercially viable electromechanical watch. Although Elgin and Hamilton had long been known for technological innovation, their singular novelty of electric power would prove to be far less ambitious than Bulova's response. Bulova's answer to modern timepiece design would be so fundamentally revolutionary, that it would ultimately drive Elgin and Hamilton out of the watch business altogether.
After examining the Elgin electric movement, Bulova assigned electronics engineer Max Hetzel to produce a new type of electronic movement which would exceed the accuracy of a conventional mechanical or electrical watch. By 1953, Hetzel received his first shipment of Raytheon CK722 transistors, and began constructing the first prototype of what would be known as the Accutron chronometric micro-powerplant, a new type of timekeeping mechanism with a tuning fork timebase.
Raytheon CK718, a high performance bin of the consumer grade CK722 used to construct the first Accutron prototype. The CK718 pictured here is marked with production date code 351, indicating the 51st week of 1953.
Departing sharply from traditional clockwork, an Accutron movement uses a transistorized oscillator to power a pair of electromagnetic drive coils. The coils act upon a magnetized tuning fork, whose alternating, vibrational motion is then directly converted into rotational motion by a microscopic jeweled ratcheting system known as an index mechanism. The most significant Accutron calibers oscillate at a rate of 360Hz, equivalent to a mechanical rate of 2.592Mbph. For comparison, quality 'hi beat' mechanical watch movements operate at a rate of 36kbph. Because of the tuning fork's extremely stable oscillations, an Accutron may be regulated to within +/-2 seconds per day or less, double the accuracy of a modern Top- or Chronograph-grade ETA mechanical movement. The tuning fork's 360Hz vibrations also give an Accutron its characteristic humming sound and smooth sweep second motion. The distinctive Accutron sweep second has only recently been replicated in modern movement designs, such as the quartz-based Seiko Spring Drive and Bulova Precisionist.
Early Accutron model 521, M0 (1960) date code, indicating the first two months of Accutron production. Solid 14K gold asymmetrical case.
Accutron model 521. This extremely early model is noteworthy as being the only 214 which does not have a waterproof screw-down back. Note the back-setting mechanism and battery hatch, unique to Series 214 devices.
Max Hetzel ultimately constructed a series of eight movement prototypes, which were then transformed into a viable product by Bulova engineer William O. Bennett. The first production movement, the 214, was introduced to the public on October 25, 1960, and sales began in November. Accutron watches were an immediate success, due in no small part to the open-dial Spaceview variants. The Spaceview makes full display of the attractive 214 movement, including the prominent tuning fork and space-age transistorized circuitry. The Spaceview was not originally intended as a consumer product, but rather a conversion kit a jeweler could install in a standard 214 to serve as a point-of-sale visual display. The Spaceview visual aid was far more effective than Bulova had imagined, and the subsequent consumer demand for converted Spaceviews rapidly pressed Bulova into producing factory models.
The Accutron would also become the first wristwatch approved for railroad use. Before the Accutron, wristwatches were deemed too irregular for railroad use, primarily because of the oscillation variance which can be introduced to a mechanical balance wheel through normal rotational wrist motion. Pocketwatches are not exposed to such rotational motion in normal use, so tend to have better regulation. The Accutron is nearly immune to such effects, easily surpassing the Railroad certification requirements.
Factory original Bulova Accutron Spaceview, Swiss variant with larger stainless steel case, M6 (1966) date code. The green plastic components of the 214 movement are believed to be composed of glass-filled diallyl phthalate.
Bulova Accutron Railroad Approved, stainless steel case.
Accutron 214 tuning forks in a 25-unit bulk pack. Accutron tuning forks are composed of Ni-Span-C, a temperature-stable nickel steel alloy in the Elinvar family. Note the conical magnets.
Accutron 214 index jewel, 10x magnification.
Accutron 214 index jewel, 60x magnification. The 214 index jewel measures approximately 0.15mm in its longest dimension, and was considered a significant technical achievement at the time of introduction.
The unique Accutron movement required a number of new test and measurement devices for proper servicing. Pictured here is the Watchmaster Products (division of Bulova) Accutron Test Set, a specialized analog multimeter.
Watchmaster Products Vibrograf B100A timing machine with Accutron test mount. The B100A is the first model of Vibrograf to support Accutron watches.
In addition to the Spaceview, Bulova also produced the Astronaut, a 214-based GMT timepiece with a 24-hour rotating bezel, secondary 24-hour hand and hack function. The Astronaut was initially developed by Bulova for the US space program, but ultimately found its greatest success in the consumer market. The Astronaut is the only timepiece to use the 214HN sub-caliber, widely considered to be the ultimate Accutron movement.
Bulova Accutron Astronaut N, M9 (1969). This is an enhanced variant of Astronaut N, with an uncommon luminous seconds hand. The majority of N variants were issued with a standard non-luminous seconds hand.
Although the 214 movement underwent numerous changes throughout its production lifespan, perhaps the most notable is the complete redesign of the electrodynamic transducer circuit. The 214 was initially equipped with a 'three wire' circuit, which uses a germanium PNP transistor. Later 214 movements were equipped with a 'two wire' circuit built around a silicon NPN transistor. It is a commonly held myth that there is no performance difference between the germanium and silicon transistor circuits, and that the switchover was simply to future-proof Bulova's parts supply in the face of emerging silicon technology. However, in 1963, Bulova published a paper in the SAE journal which states that the germanium transistor used in the 214 becomes unstable above 130°F, while silicon transistors would provide operation up to 210°F. Additionally, the germanium circuit draws excessive current when operated at higher temperatures, thus inducing premature power cell failure. The silicon circuit is immune to such effects.
Following Max Hetzel's depature from Bulova in 1963, William Bennett remained the driving entity behind Accutron product development. While previous efforts had focused on refining the 214, the future of Accutron development would be characterized by multiple new movement calibers. In 1965, Bulova released the 218, a slimmer movement than the 214 (4.4mm vs 5.5mm), with a more traditional side-exiting setting stem. The 218 was released in a range of complications not seen in the 214, including calendar functions and a jump-hour secondary timezone variant. While the 218 was a reliable, widely adopted caliber, it was never offered in a true Spaceview variant, and never achieved the enduring popularity of the 214.
Accutron model 263 with 2180 movement. The 2180 is a basic 218 sub-caliber with no date complication.
Accutron 218, sub-caliber 2181 with date complication.
Accutron 218, sub-caliber 2182 with day/date complication.
Accutron 218 Mark II, sub-caliber 2185 with quick-set secondary timezone hour hand and date complication.
Accutron 2180 movement, mounted in a special 218 movement holder.
Accutron 218 tuning fork. Note that the 218 tuning fork has cylindrical magnets, instead of the conical magnets used in 214 tuning forks.
Universal caliber 52, a licensed clone of the Accutron 2181G (sub-caliber of Series 218 with date complication).
Although the effects were not immediate, the advent of quartz marked the beginning of the end for tuning fork technology. Accutron development shifted to cheaper and smaller movements. In 1972, Bulova released the 219, similar to a 218 but with only a single drive coil and an increased use of plastic parts. The 219 was intended as a cost-reduced drop-in replacement for the 218, but was not as widely implemented as the 218. Bulova also produced the miniature 230 (1972) and 221 (1973) calibers, designed for ladies' watches. Neither miniature caliber was particularly popular or reliable.
By 1972, the 214 had been phased out, except in Spaceview and Railroad Approved models. The first-generation Astronaut had been eliminated in favor of the Astronaut Mark II, which made use of a dual timezone 2185 movement with secondary quick-set hour hand. By 1976, Bulova was selling budget-priced Accutron watches for $75, including larger mens' wristwatches with less preferable miniature caliber movements hidden inside.
Swiss-made N7 (1977) 219 with an uncommon green dial. 219-based models are externally indistinguishable from more common 218-based models.
Accutron movement, caliber 219, sub-caliber 2192.10.
Ladies' Mini Accutron, equipped with a caliber 221 movement.
Accutron miniature caliber 221, a unique, albeit problematic movement. Note the unusual circular tuning fork which encircles the battery compartment.
Ladies' Mini Accutron, equipped with a caliber 230 movement.
Accutron 230, another problematic miniature caliber. The single-coil construction of the 230 is quite different from the design of other Accutron calibers.
Decline of the Accutron
The Accutron movement would not endure. By 1969, Seiko would introduce the 35 SQ Astron, the first production wristwatch based on a quartz crystal oscillator. Bulova had been developing quartz technology since the 1950s, allowing them to engineer a quartz movement in less than a year. The resulting mechanism was the Accuquartz 224, which incorporated an IC-driven crystal timebase into a derivative caliber 218 platform. The Accuquartz 224 is noteworthy as being first quartz watch commercially available in the U.S., and the only quartz watch with a smooth sweep second hand, prior to the recent commercial release of the Seiko Spring Drive mechanism.
The Accuquartz 224 functions as an odd quartz/tuning fork hybrid, in which the timing oscillations are governed by a quartz crystal. The vestigial tuning fork and index mechanism are reduced to the role of a stepper motor. Perhaps the most advantageous features of the 224 are due to its similarities to a caliber 218 movement, namely drop-in compatibility and a large number of parts shared between the two calibers.
Bulova quartz oscillator crystals and crystal ovens.
Newly minted Accuquartz 224, circa 1972, as demonstrated by jeweler and certified Accutron technician Wayne H. Riehle (deceased). Bulova and Accutron display cases are also visible.
Bulova also expanded their product line to include primitive 'Computron' digital watches, based on emerging LED and microprocessor technologies.
Bulova 'Computron' digital wristwatch with 7-segment LED display.
Bulova ceased sales of tuning fork movements in early 1977, after selling over five million units. Two years later, Bulova was acquired by Loews Corporation, and began a long downward slide to their current diminished state. During this period, Bulova occasionally attempted to recapture their vintage market with questionable offerings, most notably a quartz-based Anniversary Spaceview, and an Astronaut reissue with an ETA automatic mechanical movement and a superfluous non-rotating GMT bezel. Both of these watches failed to deliver the fundamental characteristic of a vintage Accutron, the tuning fork movement itself.
In 2008, Bulova's assets were acquired by Citizen, a Japanese manufacturer of mid-grade dress watches. The trade name and familiar tuning fork logo live on to this day, printed across the dials of Citizen-manufactured wristwatches equipped with quartz or mechanical movements. Since the Bulova acquisition, Citizen has released a 50th anniversary limited edition Spaceview, built upon a near-exact modern reproduction of the original Accutron 214 movement. This limited edition timepiece, designed to resemble the iconic Accutron 'Alpha' Spaceview, is priced at approximately five times the current market value of an original Alpha. Parallel to the 50th Anniversary Spaceview, Citizen also developed the Precisionist line of high-accuracy quartz watches. The Precisionist features an accuracy of +/-10 seconds per year, and has a somewhat smooth sweep second hand with 16 discrete advancements per second. Both the 50th Anniversary Spaceview and the Precisionist are adorned with the misleading Bulova trademark.