Who invented the crystal oscillator

Technically that can and is said about many things. But think about it! Without crystal oscillators, we may have never seen precision timing in clocks, wide and clear radio broadcasts, or important communication methods within military and space programs.

Imagine how different our world might be without these now commonplace technologies. Have you ever wondered about the history behind these small, but important, electronic devices?

How they came to be? Who invented the crystal oscillator? And other hidden mysteries? In this post you'll get a brand new perspective of oscillators by taking a deeper look at 4 hidden crystal oscillator mysteries that many people don't know. It all started with Piezoelectricity T he electric charge that accumulates in certain solid materials such as crystals , certain ceramics , and biological matter such as bone, DNA and various proteins in response to applied mechanical stress.

This phenomena was discovered by brothers Jacques and Pierre Curie in As you can see Way to go, Curie bros! Using the concept of Piezoelectricity, the first ever crystal oscillator using a crystal of Rochelle Salt was developed by Alexander M. Nicholson at Bell Telephone Laboratories in The first quartz crystal oscillator was invented over a decade later in by Walter Guyton Cady.

For your viewing pleasure, he is also imaged below. Side thought: I wonder what he was thinking about at the time of this photo nearly years ago.

While quartz resonators were used for sonar in World War I, one of the first major uses for quartz crystal oscillators was improving radio broadcasts. Between and they produced an estimated 30 million crystal units. The radio equipment used by the armored cavalry and the field artillery divisions was designated the BC series. This equipment used frequency modulation and operated in the MHz range of frequencies.

Each set carried a complement of crystal units ranging in number from 72 to thereby requiring an extremely large number of crystal units. The crystal units, which operated in the frequency range kHz were made with CT-cut quartz plates. The production of this plant was reported to be one million units per month when it was shut down in the summer of A complete account of the development of the FT unit is given by W.

Drew and A. Although the Hawthorne plant was in a secure location militarily, it was early recognized that at least one more source for these units should be available. The technology involved in making the FT was clearly beyond the capability of most of the small plants which were successfully making the FT and CR-1 types. Accordingly a contract was awarded to the Federal Telephone and Telegraph Co. However, despite the expenditure of a large sum of money and much precious quartz and with the experience of the Western Electric Co.

One of the most critical problems faced by the QCS was the shortage of raw quartz. Although quartz is found in a few other places including the United States, practically the only source of natural quartz of electronic grade is Brazil.

At the beginning of the United States had a stockpile of about 10, pounds of quartz suitable for processing into crystal units. During about 30, kg 67, pounds of quartz was imported from Brazil. The amount imported in was 57, kg. Richard Stoiber was assigned the problem of expediting the supply of quartz. Before the end of the supply of faced quartz which could be processed without the use of X-rays was nearly exhausted and the industry was forced to begin to learn to process unfaced quartz of which a considerable quantity was still available.

Various techniques and devices were developed to enable manufacturers to use this material. These are adequately described by G. Willard in Heising, Chap. By the end of X-ray diffraction equipment began to become available to the manufacturers enabling them to effectively utilize unfaced quartz crystals. This relieved the shortage somewhat but the supply was still inadequate and steps were considered to increase the supply.

The mining of quartz was not then, nor is it now, an organized activity. The merchant, in turn, exchanged it for goods and eventually the stone reached Rio de Janiero where it was finally sold to the purchasing agent of the Metals Reserve Corp. This ad hoc system was incapable of meeting the needs of the growing crystal industry and the quartz shortage continued to become more acute.

As an example, on Easter Sunday an executive order was obtained from the White House releasing pounds of quartz which was needed for a special order for crystal units. Various steps were considered for alleviating the shortage which was partly due to inadequate grading facilities in Rio. Consequently inspection teams were trained and sent to Brazil to inspect the quartz prior to shipment.

Eventually several thousands of pounds of quartz were loaded on a ship bound for the Port of Newark. The ship was hardly out of the harbor before it was sunk by a German submarine.

In an effort to encourage the mining of quartz the purchasing agents in Brazil were authorized to double the price of quartz.

Consequently the result of the program was less, not more, quartz and the program was abandoned. It was then proposed that mining machinery be sent to Brazil. Accordingly a cargo ship was loaded with bulldozers and other earth moving equipment and dispatched to Rio. It was sunk enroute. Another ship was loaded with similar equipment. It arrived safely but most of the machinery never reached the mining areas because of lack of roads and that which did reach the quartz mining area proved unsuitable because of lack of fuel and because the nature of the operation made mechanical mining impractical.

At this time it was considered uneconomical to process stones below about grams in size. One day in Mr. This information spread quickly throughout the industry and for a time alleviated the quartz shortage.

Nevertheless, through the entire war period the quartz crystal industry lived on a hand to mouth basis and the shortage problem was eventually met, not so much by increasing the supply as by conservation. The yields were increased by making the blanks smaller and stones formerly considered unuseable were processed. Production records were maintained and with one or two notable exceptions, quartz was allocated only to the producers who could show that they were able to utilize it efficiently.

The lesson learned from the shortage of a critical raw material for which we were totally dependent on an offshore supply was not wasted. Efforts were made to find a substitute for quartz. These were unsuccessful but at the end of the war it was learned that Germany, faced with a similar quartz shortage, had made some progress toward making man-made quartz. Consequently a major effort was mounted to make cultured quartz with such success that we are now almost completely independent of the natural material.

By the middle of the task of setting up an industry was complete and crystal units were being produced in numbers adequate to meet the demand.

It was then that the second, and even more serious crisis confronted the crystal program. Reports began to filter in of extensive crystal failures both in service and in depot storage. The first responses to these reports ranged between indifference and disbelief. The progress was slow because the problem was treated as an academic question rather than a matter of the utmost urgency.

It read as follows:. The tests quickly confirmed the field reports. All crystal units failed within a few days or at most a week or two. Some of the failures were due to the phenomenon of corrosion fatigue in which the ammonia released by the phenolic holders attacked the brass connectors at points of stress causing them to break.

This problem was corrected by eliminating brass from the assembly. A much more serious problem was the ageing syndrome characterized by loss of activity and increased frequency. Many theories were advanced to explain the phenomenon and these had to be checked out experimentally. Meanwhile the manufacturers were producing crystal units at the rate of a million per month; nearly all of which were destined to be useless.

Before the end of it had become apparent that the most important factor in the ageing process was the surface of the quartz which was damaged in the process of lapping to frequency.

Particles of quartz, partially loosened by abrasion, were further loosened by the effects of water vapor, eventually breaking away completely. The presence of these loose fragments on the surface of the blank reduced the activity by damping and their loss caused an increase in frequency because of the reduction of mass.

The problem of ageing was especially severe in the CR-1unit used by the Air Force because these units operated at higher frequencies and required closer tolerances. As a temporary measure orders were issued by Wright Field that all quartz plates must be able to withstand the test of scrubbing with soap and water and a toothbrush. Soon each Signal Corps Inspector and each crystal finisher was equipped with a toothbrush and a dish of soapy water. The directive was a boon to the toothbrush industry but contributed little to the solution of the ageing problem.

By the end of it had been shown that quartz blanks which had been etched to frequency exhibited very small changes of frequency and activity even when subjected to tropical conditions. However considerable opposition existed to the idea of etching and much valuable time was lost in investigating other approaches before the decision was made to require etching. This was due to a reluctance to specify a manufacturing process which might require rewriting of the specifications and renegotiating of contracts and to a wise policy of specifying test results instead of manufacturing procedures.

Yet it was impossible to depend upon inspection procedures to insure that crystal units would remain useable and a vast amount of work had failed to reveal any other manufacturing procedure which would do so. The problem was explained in detail and the proposed remedy was presented. There was no time to rewrite the specifications or to renegotiate contracts so the manufacturers were asked to convert their production processes from hand lapping to etching. It was expected that units made by the etching process might be more expensive.

Again the industry rose to meet a challenge. The manufacturers went back to their plants and converted to the new process with such success that they produced satisfactory units at a lower cost. As one example, Ken Ross, who had converted his coil winding plant in Chicago to a facility for making FT crystal units, designed and built a continuous etching system which, with four operators, turned out as many finished crystal units as 20 operators finishing by hand lapping.

The Ross system was soon widely copied throughout the industry. Ironically, the ageing problem might have been avoided had better communication existed. The phenomenon of ageing had been noted as early as October at RCA. The work of H. LeRoy and V. Trouant led to a Company Confidential memorandum dated April 14, in which they said:. Unfortunately this work was unknown outside the RCA Laboratories until after the war and even there it does not appear to have been exploited. To provide crystal units for special purposes in the field, twelve three-man crystal grinding teams were given a three months crash course in finishing crystal units.

They were trained by Dr. These teams were provided with the necessary equipment and supplies and shipped to various theatres of the war. Upon arrival they found that many of the crystal units in depot stocks were useless and much of their time was spent in opening, cleaning and grinding thousands of crystal units to new frequencies.

Benedikter, who is today associated with the General Electric Crystal Manufacturing Facility, was a member of one of the original crystal grinding teams. Later some attempts were made to salvage the defective units and at least one company, The Hudson American Co. However most of the units were enclosed in phenolic plastic holders and many others contained brass contacts, both of which were considered unsatisfactory, leaving little besides the quartz blank to be salvaged.

It soon proved to be uneconomical to salvage the units and ultimately millions of the unetched units were destroyed. It may be worthwhile to examine the ageing episode; not to assess blame or responsibility but to see if, by doing so, we might avoid a similar debacle in the future.

It appears that the ageing problem resulted from three basic mistakes; each understandable and perhaps forgivable.

The first was to depend so heavily on an immature technology, the second was to disperse an industry so widely that it could not be properly supervised, and the third was failure to follow up with an adequate reliability test program. The recall programs of the United States automobile industry indicates that some of these lessons may not even yet have been learned.

It is difficult, if not impossible, to trace the histories of all of the firms which have been engaged in the business of manufacturing quartz crystal units. Only a few firms, notably Bliley, Monitor and Valpey still operate under their original or similar names and can show continuity of management. Most of the companies have either disappeared or have changed names and locations so many times that to trace their records is virtually impossible.

It may be of some interest to trace the history of one company; noting that it is typical of the industry. In they formed Standard Piezo Co. One of their employees was Wally Samuelson. In Hunt left to form his own company, the Hunt Corp. At the end of the war Gagne sold Standard Piezo to a group of local business people headed by John Fowler.

Later it was sold to Brown Oil Co. In Schall and Samuelson sold out to the Renwell Corp. The plant was subsequently sold to a holding company, Anchor Operating, Inc. In a sense this is true, but it is in the same sense that an antique axe which has had several new handles and a few new heads is still the same axe. A list of manufacturers of quartz crystal units dated 1 May includes the names of some companies.

One year later the number had dropped to fewer than half this number. After revival of the industry during the Korean War approximately 50 companies were engaged in the business of making crystal units. The number decreased again when the Korean War ended but has increased again in recent years. Today the industry includes between 50 and 60 companies employing about people. The typical company, if it existed, would have about employees including two engineers but the size of the companies varies by two orders of magnitude.

The two smallest, American Crystal Co. Several companies have fewer than 10 employees. The foregoing figures do not include the firms which support the crystal industry. These are more numerous than the actual crystal manufacturers and employ more people.

Among the products supplied by these firms are cultured quartz, holders and bases, abrasives, chemicals, silver and gold, electronic instruments and machine tools, and supplies in an almost endless variety. The wartime expansion of the crystal industry came to an abrupt halt with the end of the war. Contracts were cancelled, plants were converted back to civilian production and equipment was dispersed. The number of producers dropped from to below 50 in a few months.

When the Korean War came in , bringing with it a new requirement for crystal units it was necessary to subsidize the companies to obtain the crystal units needed by the Armed Services. In times of military rearmament the demand has escalated only to be followed by abrupt deescalation when the crisis was over. Until only recently the civilian requirements for quartz crystal units have been small compared with military requirements in times of crisis making continuous production impossible.

One problem in the quartz crystal business has been lack of research and development. A notable example is the program which led to the development of a cultured quartz industry. But for the most part the results have not been effectively utilized; partly due to the fluid nature of the industry. Outside a few large companies, notably the Hewlett Packard Corp. The field of piezoelectricity has always been, and continues to be ignored by the Schools of Electrical Engineering. Quartz crystal technology has been treated as an art, or even worse, as black magic.

With the exception of the students who have received formal training at Northern Illinois University under Dr. Virgil E. Bottom, most of the people in the industry have learned from one another going back to the handful of men who started the industry who had, themselves, learned in the School of Experience.

Academic neglect of the field is also shown by the dearth of literature available to the newcomer. The classic work of Cady, the books of W.

Mason and the compilation of papers by Heising include practically everything which has been published in this country. The book publishers naturally have been reluctant to make the necessary expenditures to publish books for a nonexistent clientele. Most of the men who entered the crystal industry, particularly during the war, were motivated by the challenge of a difficult job and by the desire to make a patriotic contribution as much as by the profit motive.

Many continued in the business as long as they were financially able to do so; often bidding on production contracts at prices below the cost of production in order to hang on a little bit longer.

They have done so at great financial sacrifice to themselves and to the detriment of the industry. The industry has always been too small to be of interest to Wall Street and the large corporations and technically too difficult for the small entrepreneur without adequate financial backing and scientific capability.

In those instances where large corporations have taken over small crystal companies the results have been almost uniformly disastrous. Generally speaking, the management of the large companies have attempted to apply the same production management techniques which work successfully in the production of most standard components; failing to recognize the great complexity of the apparently simple crystal unit.

Lord Kelvin further investigates piezoelectric effect in quartz crystals and develops a value for the piezo-electric constant. Cady at Wesleyan University patented a quartz crystal oscillator. For this patent, he used a quartz crystal resonator to control the frequency of an oscillator he also described the use of quartz bars and plates as frequency standards and wave filters.

It is generally accepted that Cady was the first to use a quartz crystal to control the frequency of an oscillator circuit. This is a predecessor to the Pierce oscillator configuration. Westinghouse installed a crystal oscillator for the master oscillator of their broadcast station KDKA. Many other broadcast stations use crystal controlled oscillators for controlling their signal frequency.

As channel assignments start to become closer as more stations begin broadcasting, the need for closer frequency control becomes important. Y cut crystal first discovered and used. Up until this time, X cut quartz crystals had been the only form used. Amateur radio experimenters start to use quartz crystals for the master oscillators in their transmitters. Quartz crystals also gave a much more stable signal. The AT and BT cuts for quartz crystal resonators were first seen.

A hydrothermal process for growing quartz crystals on a commercial scale was developed at Bell Laboratories. Juergen Staudte of North American Aviation invented a photolithographic process for manufacturing quartz crystal oscillators. This allowed them to be made small enough for portable products like watches. SC cut quartz crystal theorised by R Holland. The concept was not realised at this stage but just proposed in theory. First SC cut crystals become available.

They are used mainly for oven controlled crystal oscillators as they have their optimum temperature coefficient at a temperature where these oven controlled oscillators operate.