differentiator opamp circuit

Thread Starter

neiji

Joined Jul 25, 2007
19
i am having quite a difficulty to express the output voltage of the 2nd opamp, the purpose of the 33k, 10 k resistor. Even if the input is only a fixed dc value why is that i get triangular pulses at the end of the second opamp?
IS this circuit a practical one? every time i had try to use a differentiator in a practical circuit it does not work.
 

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Ron H

Joined Apr 14, 2005
7,012
i am having quite a difficulty to express the output voltage of the 2nd opamp, the purpose of the 33k, 10 k resistor. Even if the input is only a fixed dc value why is that i get triangular pulses at the end of the second opamp?
IS this circuit a practical one? every time i had try to use a differentiator in a practical circuit it does not work.
It's an oscillator. The 10k and 33k provide positive feedback, combining with the op amp to make a Schmitt trigger. The 220k and 22nF determine the frequency of oscillation. The voltage from the first op amp will change the frequency and duty cycle.

There is no differentiator in the schematic that I can see.
 
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