Can I Build a Homebrew Analog Computer Using Op Amps?

[mikejp56]

Hi All,
This is a great forum for both newbies and advanced techies alike. I am a senior level tech and I have rediscovered analog computers. I would like to build a homebrew analog computer with op amps, obviously. I have done extensive research and found that detailed schematics are in rather short supply. I have come up with a few partial schematics that I am going to try to cobble together, and see how it performs. I will be building a +/- 10V system. I want to be able to solve 2nd order differential equations, and have my young nephews use it to solve simple algebra problems.
However I have a few questions:

1) Is there any advantage to using 2 op amps, one to do a summer function followed by an integrator op amp; as opposed to using a summing junction on the input of the integrator op amp, thereby saving 1 op amp?
2) I have available both 741s and TL084s. Any preference?

Thanks for any feedback that comes my way!
Regards,
Mike

 

[schip666!]

I think you want to keep things modular at the smallest level, so separating the summer from the integrator makes for more possible interconnections. But I don't know that there's any technical reason to not combine the functions if you will always be using them together.

IIRC TL084s have less error on the input, higher bandwidth, and much higher input impedance which would improve fanout. Compare the specs and see...

 

[mikejp56]

Hi Schip666!,
Thanks for the prompt response. I will probably go with the TL084s. At about .50 each I can spliurge and separate summing junctions from integrators!
mikejp56