Sound Sensor April 23

The sound sensor we will attempt to make will detect the volume of sound. When one speaks loud or if there is a loud noise the red LED will light up. On the other hand, if the sound is not lough enough or if one is using their indoor voice, the green LED will light up. Making the circuit for the sensor will be challenging, therefore Oscar will help us build the circuit. Today he drew out our potential circuit and explained its function to us.

Circuit drawing.

The circuit will have a voltage between 0V and 5V which makes the middle ground 2.5V; the capacitor charges and discharges evenly. Our circuit will have negative feedback meaning that the output is connected back to the input voltage. In addition, the circuit will oscillate between 0V and 5V.

Hysteresis with negative feedback.

Basically, the sound coming into the microphone will be amplified by the capacitor. The comparator will enable the lights to turn on whether the red or green LED when the sound passes a threshold.

Once my partner and I built the circuit, according to the drawing, we were able to see in the oscilloscope how the circuit detected sound. Our circuit was very sensitive to any noise in the room and did not have a comparator or LEDs. It was fun seeing the voltage oscillate as the sound entered the microphone.