Sound Detector Hookup Guide

Contributors: Byron J.

Resources and Going Further

A few parting thoughts.

Troubleshooting:

If the Sound Detector is misbehaving, try the following steps.

• Double check that the power supply is clean, preferably with an oscilloscope. Irregularities on the supply will likely be present on the output.
• The gain configuration is easier to tame with the higher headroom offered by higher supply voltages. Providing the Sound Detector with a stable 5V supply, and translating output down to 3.3V will yield better results than powering the detector directly from 3.3V.
• Finally, listen to the audio output. AC-couple the audio output using a 10 uF electrolytic capacitor, with its + leg to the sound detector, and connect a small speaker or headphone. Simply listening to the output often yields clues as to what's wrong.
  • You'll be able to hear whether unexpected noises, such as wind and vibration, are being picked up.
  • If the audio output is distorted, the gain may need to be reduced.
  • If the audio output is really quiet, the gain may need to be increased.
  • If there is a constant tone on the audio output, double-check that the power supply is suitably stable. Switch-mode power supplies often introduce oscillations on the power rails.

Documentation

Design files for the Sound Detector are in the corresponding GitHub repository. This includes the Eagle files, and the Arduino example and Fritzing example we explored above.

Additionally, there are SPICE simulations of the circuit for LT Spice. One of those simulations, sound_detector-wav.asc actually analyzes the contents of a wav file (which was used to generate the diagram on page 2 of this tutorial), though you'll have to modify the file path to analyze a wav file if your own.

Finally, the Sound Detector has been added to the sensors category in the Sparkfun Fritzing Library.

See Also

• The Wikipedia page for electret microphones
• LM3914/5/6 Dot/Bar Display Driver Hookup Guide