Inverting Amplifier maximum output voltage

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Discussion Overview

The discussion revolves around the limitations of an inverting amplifier's output voltage in a physics lab context. Participants explore the relationship between the power supply voltage and the maximum output voltage observed, focusing on practical aspects of operational amplifier behavior.

Discussion Character

  • Homework-related, Technical explanation

Main Points Raised

  • One participant notes that the output voltage of their inverting amplifier does not exceed 8Vrms and questions whether this is due to the 12V DC power supply.
  • Another participant suggests that the limitation is indeed related to the power supply voltages, indicating that 8Vrms corresponds to a peak-to-peak voltage close to the total supply voltage.
  • A third participant references a technical document, highlighting that real-world op-amps have output voltage swing limitations that prevent them from reaching the supply rails, which may explain the observed behavior.

Areas of Agreement / Disagreement

Participants generally agree that the output voltage limitation is related to the power supply voltages, but there are nuances regarding the specific behavior of the op-amp in question that remain unresolved.

Contextual Notes

There are assumptions about the specific op-amp model being used and its characteristics, as well as the load conditions affecting output voltage swing, which are not fully detailed in the discussion.

moonkey
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Homework Statement


I'm doing a physics lab that involves an inverting amplifier. I'm pretty crap when it comes to electronics. I've discovered that the output voltage won't go past 8Vrms.

The amplifier is like the one here
http://en.wikipedia.org/w/index.php?title=File:Op-Amp_Inverting_Amplifier.svg&page=1


Homework Equations


none


The Attempt at a Solution


I'm thinking that this is due to the DC power supply for the op amp being 12V. Would I be right in thinking that the maximum Vp (peak voltage as measured on the oxcilloscope) which in my case is 11.5V is due to the 12V DC power supply?
 
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You are obviously using dual +/- 12V supplies for your op amp.

8V rms is about 22.4V peak-to-peak which is close to 24V, the sum of your supplies.

Decidedly, you are being limited by the power supply voltages! Every op amp requires a minimum voltage drop from its output to either supply.
 
Thanks rude man
 
See "Output Voltage Swing" on page 3.

http://www.ti.com/lit/ds/symlink/lm741.pdf

For this opamp they don't guarantee you can get within 3 or 4 V of the supply rails. eg on +/-15V rails the output can swing to +/- 12V at best depending on the output load.

Just one of the many ways a real world opamp differes from an ideal amp.
 

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