H Transistorised system with balance
The first point-contact transitor was invented by John Bardeen and Walter Brattain at the
Bell Telephone Laboratories in the United States in December 1947 (See: The Physical
Review July 15th 1948 and patent 2.623.102 USA). W. Schockley did the basic research on
the P-N junction and in 1950 R.N. Hall developed an alloy-junction transistor. It took fifteen
years until transistors were made available by the manufacturers, small enough to be
incorporated in a wrist watch. The tremendous problems caused by sparking and eroding
of the mechanical switch-contacts were now solved.
The transistor can be used as an amplifier as well as an electrical switch. In these watches it
has a switch function. When the voltage of the base of a NPN transistor becomes positive or
the voltage of the base of a PNP transistor negative, the transitor will conduct the electrical
current and will close the circuit. The current flows through the drive or impulsing coil,
the coil becomes a magnet and the balance receives an impulse in the way that has been
described in the previous chapter. The voltage to steer the base of the transistor is
generated by induction in the phase or trigger coil. The coil that can be detected in these
watches consists, in fact, of two coils wound up together. When the two coils on the
balance pass the fixed magnets, one coil, connected to the base, generates an induction
voltage, the base becomes negative or positive and the transistor conducts the current at
the same time. The driving coil gives the balance an impulse. When the balance swings
back, the trigger coil generates an opposite voltage and the transistor will stay closed.
Thus, the balance is given an impulse in the same direction each swing. This system was
invented by Etablissements Leon Hatot (ATO) in the early nineteen fifties (patent
no. 1.090.564 and 1.092.411, France 1953). This patent is used in millions of watches,
manufactured by factories all over the world. Often a stamp on the pillar plate can be
detected indicating: licence ATO or lic. ATO.
At the meeting of the French Horological Society in Paris on November 24th 1956,
Leon Hatot presented a prototype of an electronic wrist watch with rewinding motor and
a transistor instead of mechanical contacts.
The first commercial wrist watch with a transistor was the 'Bulova Accutron' caliber 214.
These watches have been dealt with in the chapter about tuning-fork watches.
The first one with a spring-balance and a transistor was the 'ESA 9150', the 'Dynotron'.
The early transistorised watches with a balance wheel are:
Related Photos: 1
Copyright © by Pieter Doensen
All rights reserved. No part of this work may be reproduced or used in any
forms or by any means - graphic, electronic or mechanical, including
(but not limited to) photocopying or information storage and retrieval
systems - without written permission from the copyright holder.