Let's Make Robots!

Sound Sensig

I want to find a simple, easy, small, solid circuiti to detect environment sound pressure level

can anyone post a  good schematic?


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Sparkfun has a damn small electret microhone breakout board with amplifier. Here is the schematic.

no luck with my schema

it works fine, but is very prone to motor noise



 i have tryed to decouple all inserting caps and inductors but it seemms that motor produce frequancy near to audible band so it's tricky !

 sparkfun is interesting piece of hardware... wandering if it's immune to noise

I have recently been trying to improve my sonar with noise filtering. The simplest way is to put a small capacitor, start with 220pF across your 1M feedback resistor. A lot of motor noise is high frequency. This capacitors reactance decreases with frequency so that effectively the amplifier does not amplify high frequencies as well as it does low frequencies.

cute infos.......!

going to test

reporting back soon

done some test

puting cap on feedback resistor is effective !

but... damn, i need at leat a 1nF cap to suppress motor noise decently

with this capacitance there is a drawback: mic frequencies are suppressed too :(

I can only suggest that you put a 2.2uF bi-polar (non polarised) electrolytic capacitor across your motor as well as a 0.1uF monolythic. Monolythic ceramic capacitors have a low ESR which makes them ideal for noise0 suppression.

Try using shielded cable for the mic as well as the motors.