HP Hewlett Packard 200CD wide range oscillator

Model 200CD Wide Range audio Oscillator, 1952


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 200CD and its sister instrument, the Model 200AB, were introduced at the same time in 1952. These new oscillators represented a substantial increase in versatility over previous ones. For example, the frequency range of the 200CD (5 cps to 600 kc) was such that it replaced two of the older HP oscillators, Models 200C and 200D, which were discontinued. This was accomplished without an increase in price. The wide frequency coverage made this instrument very valuable as a general purpose oscillator.

In addition to advances in electrical design, the cabinetry of the new oscillator was redesigned. The cabinet width was reduced to save bench space, while the appearance was designed to be more pleasing and to aid in operation. One of the improvements was a large, 6-inch tuning dial.

The 200CD was used for testing servo and vibration systems, medical and geophysical equipment, audio amplifiers, sonar and supersonic apparatus, carrier telephone systems and video frequency circuits.