Room Noise Detector

Every room has a noise level,you can detect the noise level of your room with noise room detector. You can see the series of noise detector it's look like simple circuit and everyone can make it.

This circuit is intended to signal through a flashing LED, more than a fixed threshold, room noise, chosen from three fixed levels, namely 50, 70 and 85 dB. Two op amps provide the necessary gain of the circuit sounds like a pick-up is a miniature electric microphone to drive the LEDs. When SW1 at the top of the circuit off. The power of the second, third and fourth circuit and set the entry threshold is 85, 70 and 50 dB. Current drawing is less than 1 mA with LED off and 12 15 mA when the LED is steady on.

Room Noise Detector Components :

R1____________10K   1/4W Resistor
R2,R3_________22K   1/4W Resistors
R4___________100K   1/4W Resistor
R5,R9,R10_____56K   1/4W Resistors
R6_____________5K6  1/4W Resistor
R7___________560R   1/4W Resistor
R8_____________2K2  1/4W Resistor
R11____________1K   1/4W Resistor
R12___________33K   1/4W Resistor
R13__________330R   1/4W Resistor

C1___________100nF  63V Polyester Capacitor
C2____________10µF  25V Electrolytic Capacitor
C3___________470µF  25V Electrolytic Capacitor
C4____________47µF  25V Electrolytic Capacitor

D1_____________5mm. Red LED

IC1__________LM358  Low Power Dual Op-amp

Q1___________BC327  45V 800mA PNP Transistor

MIC1_________Miniature electret microphone

SW1__________2 poles 4 ways rotary switch

B1___________9V PP3 Battery

Clip for PP3 Battery

Place the small box containing the circuit in the room where you intend to measure noise. The 50 dB setting is provided for controlling noise in the room at night. If the light is constant, and often bright flashes, the room is inadequate and too noisy to sleep. The setting is 70 dB for residences. If this level is often exceeded during the day, your apartment is rather uncomfortable. If the noise is constant, over 85 dB for 8 hours a day, you live in a dangerous environment.