The maximum output sweep was virtually identical for all R2 values tested and R2 = 10K yielded the lowest noise in silence. These are the results for my particular setup. The easiest way to test which value works best is to use a trim-pot Sound Most sources suggest using a 1K ~ 10K resistor for R2. At 20x gain, the output already covers 75% of the 0 ~ 1024 range. It may push the output range a bit closer to 0 ~ 1024, but will increase the noise as well. Increasing the gain to 50x or 200x is unlikely to bring much improvement. The current draw of the sensor was 5.54mA. A loud knock gives a decent output sweep, but the readings in (relative) silence cover quite a wide range. V_OUT_UC is connected to Arduino’s A0 pin and the Min-Max sketch is uploaded. Let’s see how the LM386 sensor fares, in its 20x gain configuration (no C2 capacitor). * These particular values are just an exampleįor battery-powered applications, the current draw of the circuit may also be a concern. This makes it easier to set a threshold for detecting sounds of a given strength. Moderate sounds should have readings somewhere in between. When there’s a very loud sound, the readings should sweep all the way to. In silence, an ideal sound sensor should consistently give readings of 511-512 – half of the 0 ~ 1023 range, corresponding to 1/2 VCC = 2.5V. Sound sensor for the ArduinoĪrduino’s analog pins map a 0 ~ 5V voltage to a 0 ~ 1023 integer. If volume control is needed, the VR1 potentiometer from the original schematic can be added back, before the input pin 3. The voltage at V_OUT_UC is biased at 1/2 of the supply voltage VCC and is the better option for microcontroller input. V_OUT carries an AC-only voltage and should be used when interfacing with another piece of audio equipment.
In this schematic, a LM386-based audio amplifier takes its input from an electret microphone.
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