|Bulova, IWC, Longines, Omega, Patek Philippe, Rado, Rolex
|Central Hour Hand, Central Minute Hand, Central Seconds Hand, Date Window at 3:00
|Distinguishing Technical Characteristics
|Production: 1970 – 1972
Beta 21 was the name of the first full-production Swiss quartz movement with integrated circuit control. Launched April 10, 1970 at the Basel Fair, the Beta 21 movement was the product of 5 years development by a consortium of many Swiss watch firms. It was used in production watches from many well-known companies, including Bulova, IWC, Omega, Patek Philippe, Piaget, Rado, and Rolex. Although successful by industry standards, the Beta 21 movement was quickly surpassed technically and was retired from production within a year or two, with just 6,000 produced.
CEH Beta Quartz Technology
The Beta 21 movement used a quartz crystal that oscillated at 8,192 Hz. A custom MOS integrated circuit (IC) with a 5-stage frequency divider reduced this to 256 Hz, and this was used to drive a vibration motor which moved the wheel train. The original Beta 1 movement had used a 14-stage frequency divider and anchor stepper motor to move the wheel train 1 step per second, but the current draw of the primitive MOS IC technology was too great. The Beta 21 motor design was based on the Beta 2, which was functionally quite similar.
The integrated circuit (IC) developed by the CEH included both the “command circuit”, which powered the quartz rod resonator, and the “counting circuit”, which divided the frequency. This was in contrast to the Longines Ultra-Quartz, introduced 8 months earlier, which used discrete electronic components rather than an integrated circuit. The team developed a simple driver circuit with four resistors and two transistors that was compatible with the IC technology of the time.
The CEH design since Beta 1 included a frequency adjuster and thermocompensation circuit. The adjuster used a miniature switch which adjusted the frequency of the crystal in increments of 0.2 seconds per day after casing, an important advancement. The temperature compensation design engaged a capacitor at 12º C and was implemented in another MOS IC. These allowed the Beta 21 movement to achieve much better accuracy than the non-compensated Seiko quartz movements also tested in 1968.
The calendar wheel was adjusted using the crown in a novel way: The crown was pressed in and rotated to advance the calendar without interrupting the operation of the movement. This preserved the running timekeeping, and owners measured accuracy as good as one second per month.Images are taken from official publications and are used here for commentary and educational purposes. Copyright is held by the original owner as noted.