Jim Williams and Electronic Music

Analog circuit guru Jim Williams passed away on June 12, 2011. While he never expressed a personal interest in electronic music, he did write several interesting application notes for National Semiconductor Corp that are relevant to electronic music (even if NSC didn't credit him on the app notes).

App Note 262, Applying dual and quad FET op amps (which includes a "Voltage controlled sine wave oscillator" on page 4)
App Note 263, Sine wave generation techniques
App Note 286, Applications of the LM392 comparator op amp IC (which includes the often-cited "Exponential V/F converter for electronic music" on page 4)
App Note 294, Special sample and hold techniques
App Note 299, Audio applications of linear integrated circuits
App Note 311, Theory and applications of logarithmic amplifiers

For more information about the application notes that he wrote for National Semiconductor, see this research bibliography or the complete bibliography.

Also, Jim wrote many, many app notes for Linear Technology, including App Note 14, Designs for high-performance voltage-to-frequency converters, which includes "e^x transfer function V-to-F converter" on page AN14-14. For more information about the sitxy-two app notes he wrote for Linear Technology, see the blog Reading Jim Williams.

Footnote: Of course, I am not the first person to realize Jim's authorship of these app notes. In fact, I found the following quote on page 12 of Barry Klein's 1995 update booklet to his book (Barry Klein, Electronic Music Circuits, Indianapolis: Sams & Co., 1982) where he discusses discrete voltage-controlled-oscillator circuits. The two application notes that he lists are National Semiconductor AN-299 "Audio Applications of Linear Integrated Circuits" and Linear Technology Application Note 14 "Designs for High Performance Voltage-to-Frequency Converters".

AN-299 Audio Applications of Linear Integrated Circuits
LT1055 Data Sheet/Application Note 14
Jim Williams of Linear Technology wrote both of these application notes. I wrote him about them and he gave me a little background on them. The AN-299 VCO utilizes the CA3046 transistor array. He stated that even if the exponential transistor was ideal the performance would be degraded by the ramp reset time. His second circuit in LT1055/AN14 notes utilizes a charge pump IC -- the LT1043 -- to eliminate the dead time errors. He thinks this circuit has about a 2X improvement in exponential performance...

I want to publicize these facts, so that Jim gets the credit he deserves.

Written August 2011 by Kent Lundberg.
Updated January 2012.