OSCILLATORS

Telephone engineers use oscillators to test the audio performance of telephone lines and circuits. Model 87F is just a simple 1kHz oscillator. A more sophisticated device is the HP236A. This instrument is based on the Wien bridge principle, the same as  used in the HP200A, the first product of the famous Hewlett Packard company. In 1939, both Bill Hewlett and David Packard attended classes taught by Stanford professor of electronic engineering Frederick Terman, the father of Silicon Valley. He stimulated the couple to form an electronics company, as he did with many of his students.

The model 236A has an output impedance of 600Ω, making it suitable for holding the line when testing the signal path through a telephone exchange. It can generate a low distortion sine wave between 50Hz and 560kHz.