Dr. Steven Packard

Hewlett and Packard's first financially successful product was a precision audio oscillator known as the HP 200A, which used a small incandescent light bulb (known as a "pilot light") as a temperature dependent resistor in a critical portion of the circuit, and a negative feedback loop to stabilize the amplitude of the output sinusoidal waveform. This allowed the HP 200A to be sold for $89.40 when competitors were selling less stable oscillators for over $200. The 200 series of generators continued production until at least 1972 as the 200AB, still tube-based but improved in design through the years.[citation needed]

One of the company's earliest customers was Bud Hawkins, chief sound engineer for Walt Disney Studios, who bought eight HP 200B audio oscillators (at $71.50 each) to be used in the animated film Fantasia. HP's profit at the end of 1939, its first full year of business, was $1,563 on revenues of $5,369.[13]