What does this opamp configuration do?

4 replies · 2K views · last reply
dla
Messages
27
Reaction score
0

Homework Statement


Trying to figure out what this opamp does but can't pinpoint it.

Homework Equations


The Attempt at a Solution


The one with the capacitor looks like an integrator. I attempted to build this circuit to see what it does. At node B I saw a triangle repeating waveform, node A gives a square oscillating waveform and C is some sort of horizontally flipped RC curve which can been seen with the file I attached. Anyone have any idea the name of this circuit?
 
Attachments
  • Oscilloscope-style waveform plot showing a repeating sawtooth-like signal with three cycles, each rising gradually then falling sharply, between two dashed horizontal reference lines.
    555RCcurveGraph.jpg
    6 KB · Views: 502
  • Circuit schematic of two op-amps: the left stage feeds node A, a 22K resistor and 100nF feedback capacitor form an integrator to node B, and a 5K6 resistor from A to C with 2K2 and 1K2 resistors back to the left op-amp's non-inverting input.
    lab1.JPG
    9.5 KB · Views: 479
Last edited:
Hint: The word you are looking for begins with an "O" and is used to describe a family of systems including a pendulum.
 
I'm still quite not sure.. The only thing that comes to mind is an oscillator?
 
Oscillator will do :-)

I suppose "Triangle Wave Oscillator" or "Hysteretic Oscillator" or "Relaxation Oscillator" might get you another half mark.

The right hand op-amp is indeed an inverting integrator. It integrates the "constant" output of the left hand op-amp.

The left hand op-amp is configured as a comparator (with hysteresis) and it's output is a "constant" VCC or -VCC.

You can actually make one by merging the functions each op-amp performs into one op-amp. See wikipedia for that..

http://en.wikipedia.org/wiki/Relaxa...2.80.93based_electronic_relaxation_oscillator