[sdiy] Integrator frequency calculation

[Justin Owen]

Hello,

Since the answers I got from this list about my DC summing calculations were so much clearer than my interpretations of various textbooks - I thought I'd just come straight to the source this time.

I'm trying to understand how to calculate the frequency output of an op amp integrator. I understand that it's a relationship between the change in voltage over time and the current across the capacitor.

My integrator is being fed a square wave, the output is a triangle wave. 12V single supply with VCC/2 = 6V, 10nF cap and approx. 28K6 input resistor. Triangle isn't biased exactly on VCC/2 right now - but there is a reason for that.

Here's what I have so far:

Integrator outputs a triangle wave of approx. 200Hz from a square wave with a 'low' state of approx. 5.29V and a 'high' state of approx. 6.25V. That's a change of 0.96V every 0.005 seconds.

or..

Integrator outputs a triangle wave of approx. 574Hz from a square wave with a 'low' state of approx. 4.47V and a 'high' state of approx. 7.17V. That's a change of 2.7V every 0.0017etc. seconds.

That's what I know - the rest is speculation. So - how do I take V, I, R and C - and get F.

Thanks all,

Justin