op-amp help for a newbe

[lacy]

Peter is correct. I just missed that in my analysis. But with that said it still doesn't address the integration/diferentiation problem.

[KEN_KEN]

Thank you for all the help, 

I tried that  initially and decided for clarity to remove them. I never saw any red x on any of the amps the supply was removed from. I now put the supplies back onto the other two amps. I getting an output of 3.8 vdc on the final stage. shouldn't that be a sine wave?

Ken

[lacy]

I just checked your circuit and even though Peter was right in his observation, it still did not solve the problem and right now I have no solution. I still not able to get the op amps to do integration and differentiation.

I am really sorry, but this one has me stumped.

[KEN_KEN]

Did you get a chance to try the single stage op amp circuit I sent earlier.

Ken

[lacy]

Yes, I did try that and I couldn't get the waveform to change shape. I have also been experimenting with circuits from the internet and they do not function like I think they should. I am going to continue looking at this, but I am not as confident of figuring out a solution. If I would accidently come up with something I will definitely post it for you. I would also appreciate that if you would happen to figure it out to post what you found.

If Nestor or one of the other team members is monitoring this discussion please chime in at anytime and give us a hand (or a mind in this case).

[KEN_KEN]

Thank you and I will also keep you informed if I figure it out.

Please if anyone knows what's going on here we would love to hear from you.

Ken

[lacy]

Solution possibly found!!!  I tried every way I know to get a sine wave to transform and I just couldn't find a way to do this. What I did find is that if you input a square wave it will differentiate and integrate just fine. Apparently it just isn't going to be able to transform a sine wave the way you want it to. I am going to post my single op amp circuit (which is your circuit that I have drastically modified) for you to look at.

[KEN_KEN]

Lacy,

Thanks for all your efforts The modification you sent has an sawtooth output with no gain (4.45 Pk-Pk, 1.39 RMS) compared with the input (5V Pk-Pk, 2.25 RMS) I'm sending you a picture of what I'm talking about along with the sim file.

I found some op- amp examples that you can run in NI, I'll send them to you later

Ken

[KEN_KEN]

Here are the sim fils I promised.

Ken

[lacy]

You are correct. I was just concerned more with getting the waveform to look right. It is the capacitor that is causing this. It is attenuting the signal. If you lower this capacitor to 10pf you will see the difference..  When you do this it does change the wave shape some. I believe that in order to get a true triangle wave from this circuit you will end up losing some gain.

Thanks for the circuit files. These will come in handy.

Message Edited by lacy on 08-22-2007 11:14 AM