HP 200A Oscillator, ca.1942. This unit was purchased during the Manhattan Project at Los Alamos during WWII.

It has a 5 digit PN#34980 stamped on the from with yellow military marking ink characteristic of items purchased before the Manhattan Project was turned over to the Atomic Energy Commission in 1947.  During its life at the LASL, it was also property of Z-division (see photos).  Z-division ultimately became Sandia National Lab in Albuquerque, NM.

The HP 200A was the first product made by Hewlett-Packard and was manufactured in Dave Packard's garage in Palo Alto, CA.

It was a low-distortion audio oscillator used for testing sound equipment. It used the Wien Bridge Oscillator circuit, that had been the subject of Bill Hewlett's Masters thesis. It was also the first such commercial oscillator to use a simple light bulb as the temperature-dependent resistor in its feedback network. The light bulb was an inexpensive and effective that not only kept the oscillator output amplitude constant, but it also kept the oscillator's loop gain near unity. The latter is a key technique for achieving a low distortion oscillator.