View single post by wmikrut
 Posted: Nov 25th, 2011 10:25 PM
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wmikrut

 

Joined: Nov 21st, 2011
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Hello everyone... thank you for the welcome and the replies.
Attached is a picture of the device I built.

I did find a few things I was doing wrong.

First off, the device is not shielded... so I will need to mount the board inside of a metal box.

Some problems were -- I used a computer to do a sample recording of 15 minutes... and since the device wasn't shielded I was getting interference from my wireless network adapter.

Secondly, I have a motion sensor in my hallway that automatically turns on a light when you walk through the hallway.  Apparently this devices creates a lot of noise when it's first activated... and it doesn't help that I have a cfl in place of a light bulb.

So... I have a few things to correct before trying another recording... but it was very interesting to see so many people heard 'something' in the recording as I did.

I can't wait to shield the device and try it again with the motion sensor deactivated.
I forgot to mention that I did amplify the recording -- but I needed to as the recorded audio is very, very quiet.

I was also concerned about using a 100uH coil instead of a 500uH coil... I am trying to track down a supplier to buy a couple of different coils to see if I get better results.

Thank you all for your replies!

Attached Image (viewed 482 times):

2011-11-25 23.11.43.jpg