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(25) Resistance Computation adder-subtractor circuits - SlideRule - 02-18-2022 10:05 PM
An excerpt from Simple Rules for Choosing Resistor Values in Adder-Subtractor Circuits, volume 10, no. 1, 1976, pages 14 & 18, analog dialogue magazine, for the HP-25 programmable calculator.
THE PROBLEM
I want to take a linear combination of analog voltages with both positive & negative coefficients, using a single operational amplifier …
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A SOLUTION!
This is a mechanized procedure for computing all the required values. It works in all practical cases, for any number of inputs on either side, whether the circuit is inverting-only, non-inverting only, or an adder-subtractor, and for all reasonable values of gain or attenuation.
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That's all, folks!
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If many similar networks with differing gains are to be designed, the reader may be interested in an HP-25 program that will provide fast and accurate implementation of the above procedure for up to 3 inputs on each side. It appears on page 18.
BEST!
SlideRule
RE: (25) Resistance Computation adder-subtractor circuits - Steve Simpkin - 02-19-2022 05:07 AM
That is very cool! Over the decades I have used many Analog Devices parts in various products including Op-Amps, analog gates, level converters, audio CODECs and DSPs. It is one of my favorite electronic parts companies.
The HP-25 program on page 18 seems reasonably clever. I have always been amazed at what you can do with 49 steps. I found it so capable that I used my HP-25 for 10 years though High School, college and my first engineer job.
Thanks!