Microphone Switch

[Tenatious]

Hello guys,

Thanks in advance for any welcomes to the forum. Being looking at it for a while but haven't needed to register yet.

Right, to the point:

My GCSE project is a sound actiavted door. And the person needs to be on the pressure pad before it opens. I have the pressure pad and motor reverse part sorted. Just need to do the microphone as a switch now.

Bit stuck

Not sure how to get my electet microphone to act as a switch. So when a certain amount of sound is picked up, it registers as "switch pressed" and then the motor runs and eveything carries on as it does without the sound

Thanks for any input

 

[audioguru2]

Hi Tenatious,
Welcome to our forum. ;D
An electret microphone needs a small amout of power. Usually a 10k resistor is connected to it from a positive supply of about 9V.
The output level of microphones is very low. You will need to amplify the output of the mic with a mic preamp circuit.

The output of a mic preamp circuit is AC. You will need to rectify and filter it to get DC when there is a sound at the mic.

The filtered output of the rectifier will probably need its current boosted with a transistor or a Mosfet to provide enough current to activate the motor.

 

[Fowkc]

Most switches activated by sound that I've come across use a circuit similar to this one:
http://www.fowkc.com/elec/clapper.shtml

That's electrect mic --> amplifier --> input to logic / microcontroller.

Mine works, but I'm sure it's not perfect.