Electronic Circuits and Tutorials
Electronic Schematics - D

Decibel Meter Circuits

Audio VU Meter -  LM324,This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324.

LED Decibel Meter -  The circuit below responds to sound pressure levels from about 60 to 70 dB. The sound is picked up by an 8 ohm speaker, amplified by a transistor stage and one LM324 op-amp section. You can also use a dynamic microphone but I found the speaker was more sensitive.

Precision Audio MilliVoltmeter -  Measures10mV to50Volt RMS in eight ranges Simply connect to your Avo-meter set @50µA range.

Room Noise Detector -  One LED monitors three levels: 50, 70 & 85 dB.  Useful to detect too noisy environments.

Sound Level Meter -  One chip replacement for the standard analog meters, based on LM3915 audio level IC.

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