super sensitive microphone

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Any ideas how to record faint background noises?  All the mikes I tested you
have to speak into.

Herc

Re: super sensitive microphone



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We sure need more information on this question!

JERD



Re: super sensitive microphone


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A satellite(s) follows me everywhere making noise (voices) probably by heating
the air
at accoustic frequencies with a MASER.

For 7 years straight, verbally abusing me all day every day, and no its not in
my head.

Herc aka The Truman


Re: super sensitive microphone



:>
:>> Any ideas how to record faint background noises?  All the mikes I tested
:>> you have to speak into.
:>>
:>> Herc
:>
:> We sure need more information on this question!
:
:
:A satellite(s) follows me everywhere making noise (voices) probably by heating
the air
:at accoustic frequencies with a MASER.
:
:For 7 years straight, verbally abusing me all day every day, and no its not in
my head.
:
:Herc aka The Truman


Allo..allo! I think we've got a live one 'ere....

Re: super sensitive microphone


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Most regular omnidirectional electret mic elements are very sensitive.
http://jaycar.com.au/productView.asp?ID=AM4010
Used in their zillions in standard PC desk mics and headsets etc.
Gain'em up as required.

Dave.
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Re: super sensitive microphone


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I had a FM bug that was more sensitive than the human ear, when someone was
pouring
a cup of tea I could hear it swirling and the pitch increasing.  But the FM bug
I just got
from Talking Electronics was not very sensitive.

Can you buy something like a birdwatchers sound recorder?

Herc


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All of the Talking Electronics bugs I built as a kid all had a standard
electret microphone and could pickup anything "better than the ear" as
you've found before.
The new one you have obviously doesn't have enough gain, and/or has an
insensitive mic. Perhaps it's designed for a different application?
Can you change the gain on the front end amp?
I'm sure Colin Mitchell at TE will be able to tell you what you need to
know.

Dave.

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OK maybe its my radios.  I tested it on a radio with a broken antenna and a
MP3 player with a digital tuner, which went up in increments of 0.05 MHZ
so it might have been out a bit.  I'll get another radio to make sure it's not
the
bugs fault.

Herc

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A tuning step of 0.05 MHz is fine for bugs (unless the bug's deviation is
really really low).

The broken antenna will restrict the range but not the recovered audio.




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Reception was really poor on both.  Too late now I ordered a $15 radio from DSE.
The frequency was 87.8 MHZ and the dial on the radio I ordered started at 88MHZ
so should be close, I pulled the coil as wide as it will go to increase the
frequency.

I asked Colin to mark on the bug what frequency it was, and he put 87-92!

Herc


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Increase the value of the microphone bias resistor to increase its
sensitivity.

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Was just browsing from some old TE books yesterday :)

Some of the TE mics were designed more for handheld microphone use (ie not
very sensitive) whereas others were designed to be very sensitive.

A very senstive mic overloaded when spoken into at close range and hence it
needed to be throttled back.

Look for a resistor from the positive rail to the electret.

The lower the value the resistor (down to a few k ohm) the more sensitive
the mic.  Conversely a higher value mic resistor (say 47k) won't be that
sensitive.

Experiment with lower values to make it more sensitive.



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**Depends on what you are attempting to do. Usually, a good directional mic
will provide what you want. There are a couple of variants on directional
mics. You can construct something yourself, using a mixing bowl, with the
microphone mounted at the centre. Similar to a satellite dish.


--
Trevor Wilson
www.rageaudio.com.au



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Maybe there's a maser beam converter program somewhere that will convert the
beam into audio.

Rheilly P



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**Huh?


--
Trevor Wilson
www.rageaudio.com.au



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Did you read the post ??



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**Yep. I saw no mention of microwaves. The reason for the dish is to
'amplifiy' SOUND waves.


--
Trevor Wilson
www.rageaudio.com.au



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It sounds like someone talking softly in the next room.  Easy to hear everything
they say, but the mike on my laptop can't pick it up.


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The maser beam does make audio!  You can hear half a dozen American agents
talking all day.
Given 1000s of people in Townsville have heard them, how would you explain a
noise source
that follows you everywhere?

Herc


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Lets assume for a moment there is a satellite that can punch a maser
beam powerful enough to heat surface air enough to modulate audio.

You'd spot it's presence by the burnt spot on the ground caused by the
microwave heating and by people exploding as their fluids turn to steam.

   Still it would be awesome to throw your voice at right/wrong place,
picture two teams of diplomats sitting tensely at the negotiating
table as one party awaits the reply of the other and a voice suddenly
says the wrong thing out of nowhere.

    In actual fact I suspect you are hearing a certain Sydney toaster/
microwave oven repairman due to cold weather atmospheric ducting of
microwaves under repair.

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That's possible. You can buy directional speaker systems now. Woody Norris
was one of the first people to develop practical ones that worked. Here is a
demo (not that you can really hear the effect of course)

http://www.youtube.com/watch?v=HF9G9M0cR0E

http://www.explainthatstuff.com/directional-loudspeakers.html

Dave.

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