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Model 200A audio oscillator, 1939


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The Model 200A was HP's first product.

An audio oscillator is an instrument that generates one pure tone or frequency at a time. Through the years, HP oscillators were used to design, produce and maintain telephones, stereos, radios and other audio equipment.

The Model 200A began as the subject of Bill Hewlett's master's thesis at Stanford University in the late 1930s. Bill had the innovative, elegant and practical idea of using a light bulb in a Wein bridge oscillator circuit to solve the problem of how to regulate the output of the circuit without causing distortion. Other oscillators that were available at that time were costly and unstable. By the clever use of the light bulb, Bill was able to simplify the circuit, improve the oscillator's performance and reduce the price.

Dubbed the 200A to make it seem like the company had been around for a while, this instrument represented the first low-cost method of measuring audio frequencies.

Bill and Dave Packard priced the 200A at $54.40 not because of cost calculations but because it reminded them of "54.40' or Fight!" the 1844 slogan used in the campaign to establish the northwestern border of the United States. The price was considerably less than competitive equipment then on the market, which was priced from $200 to $600.

Bill and Dave made the first of these in the garage behind Dave's house and baked the paint on the panels in Lucile Packard's oven. Lucile claimed the roast beef never tasted right after Bill and Dave started using the oven as HP's first paint-baking facility.

In a 1985 letter, Dave described Hewlett's audio oscillator as "the foundation on which Hewlett-Packard Company was able to grow into the largest manufacturer of electronic instruments in the world, the keystone that allowed four and one-half decades of major contributions to electronic measurement technology and equipment."

This 200A is Serial No. 12; likely produced in the Palo Alto garage.

Additional information:

  • Read a story on the 60th anniversary of the patent for the 200A originally published on hpNOW, an internal HP web site.

  • Read the HP 200A United States patent No. 2268872. (PDF, 304KB)

Permission to copy without fee all or part of this publication is hereby granted provided that 1) the copies are not made, used, displayed, or distributed for commercial advantage; 2) the Hewlett-Packard Company copyright notice and the title of the publication and date appear on the copies; and 3) a notice appears stating that the copying is by permission of the Hewlett-Packard Company.

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