(25) Resistance Computation addersubtractor circuits

02182022, 10:05 PM
Post: #1




(25) Resistance Computation addersubtractor circuits
An excerpt from Simple Rules for Choosing Resistor Values in AdderSubtractor Circuits, volume 10, no. 1, 1976, pages 14 & 18, analog dialogue magazine, for the HP25 programmable calculator.
THE PROBLEM I want to take a linear combination of analog voltages with both positive & negative coefficients, using a single operational amplifier … … 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 invertingonly, noninverting only, or an addersubtractor, and for all reasonable values of gain or attenuation. … That's all, folks! … If many similar networks with differing gains are to be designed, the reader may be interested in an HP25 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 

02192022, 05:07 AM
Post: #2




RE: (25) Resistance Computation addersubtractor circuits
That is very cool! Over the decades I have used many Analog Devices parts in various products including OpAmps, analog gates, level converters, audio CODECs and DSPs. It is one of my favorite electronic parts companies.
The HP25 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 HP25 for 10 years though High School, college and my first engineer job. Thanks! 

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