Speaker/Microphone and Inverting Op Amp

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SUMMARY

The discussion centers on the use of an 8Ω speaker as a microphone and the application of an inverting operational amplifier (op amp) configuration. It was established that the typical voltage level from an 8Ω speaker used in this manner can vary, but specific measurements were not provided. Additionally, it was clarified that an inverting op amp can operate stably with a gain of less than 1, countering the misconception that such configurations are inherently unstable. This setup is intended to attenuate audio signals for compatibility with circuitry, such as that found in a Walkie-Talkie.

PREREQUISITES
  • Understanding of audio signal characteristics and voltage levels
  • Knowledge of operational amplifier configurations, specifically inverting op amps
  • Familiarity with audio circuitry, particularly in relation to Walkie-Talkies
  • Basic skills in using oscilloscopes for measuring electrical signals
NEXT STEPS
  • Research the voltage output characteristics of 8Ω speakers used as microphones
  • Study the stability criteria for inverting op amp configurations
  • Learn about audio signal attenuation techniques in electronic circuits
  • Explore practical applications of op amps in audio processing
USEFUL FOR

Electronics enthusiasts, audio engineers, and students studying audio signal processing and operational amplifier applications will benefit from this discussion.

Jiggy-Ninja
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1) What is a typical voltage level coming from an 8Ω speaker being used as a microphone to record a human voice at average volume? I kept forgetting to bring it to school to measure it's output with the oscilloscope, so I'm wondering if anyone here knows it.

2) I seem to remember reading somewhere that using an inverting op amp configuration with a gain of less than 1 was unstable, or otherwise bad for some reason. I can't remember where I read it or why it said it was bad or anything else. This op amp would be used to attenuate an audio tone to a level manageable by the circuitry that formerly had the speaker hooked up to it (a Walkie-Talkie). Would there be any problems with this setup, or is my spotty memory unfounded?
 
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An inverting op amp is not unstable with a gain < 1
 

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