Need help for electret mic preamp

[MountainRescue]

are there any folk here who have used a ssm2167?

 

[audioguru]

A noise gate:
'ello, 'ow are 'ou?

It misses the first sounds of every word you 'eak.
Whoever you talk to will need to learn Cockney.
But it nicely reduces all the noise when you are not speaking.

 

[MountainRescue]

so its much like a VOX switch? Is it possible to modify the circuit to become a VOX switch?? I hope so as my Air band does not have a built in VOX switch... please tell me this can be done with a flick of a switch with this component...
editing the noise when I'm not speaking is not a problem... as I will not be pushing the PTT switch... remember this for a 2 way radio application not a stage performance...

 

[audioguru]

The noise gate is something like VOX. The mic signal is attenuated when you are not speaking then when you begin to speak with sounds louder than its theshold it applies full gain after it wakes up. Many words begin with sounds that are not loud vowels so it will turn on 'oo 'ate. Then nobody will know what the heck you are talking about.

'ayday, 'ayday. 'y 'gine 'as 'it and I 'ill 'and.
Your engine quit and you are going to do what???

 

[georgel2]

Where can I find a circuit diagram of an electret mic preamp that is fed by bias only and not from additional battery? Like the one in telex headphones? The circuit should simulate a carbon mic...

 

[Aldo]

Hi guys
I don't know if this thread is still active.
Having problems with a David Clark aviation headset with M-7 electet microphone installed. Apparently the capsule and preamp circuit went bad. So I gotta replace it
I made the one that Mountain Rescue posted worked fine.
Like to try the one that Audioguru posted....anyone knows how to power it using the power that comes on the microphone line (general aviation microphone) (is it phantom power??)
Thanks in advance

Al

 

[valve]

Are electret and condensor mic same? How is the sensitivity comparing to dynamic type?What about speaker mic?? I am going to do a parabolic dish microphone for capturing distant, micro sounds. Which mic is good for that. Also can I use the amp suggested by audioguro for a wide frequency range. I want it to capture sounds of birds, small creatures and even low frequency sounds also.

 

[audioguru]

An electret mic is a condenser mic that has a 48V charge built-in. A condenser mic needs to have an external 48V supply to power it. An electret mic meeds about 0.5mA at a few volts to power its built-in FET impedance converter.

A dynamic mic usually has a peak in the upper frequencies (singers like the peak because it causes "presence") and is not as flat as an electret mic.
Electret mics have about the same sensitivity as dynamic mics.

A speaker has a very strong resonance so is not used as a mic except in a cheap kid's walkie-talkie or in a cheap intercom.

 

[Aldo]

Thanks audioguru for your explanations. I am using two different headsets, one with a dynamic microphone and the other one (the one that I am trying to fix) with a electret. The dynamic mic (M1-DC) has a good output but has a tendency to pick up a lot of cockpit noise. The electret works much better
That s why I am trying to bring it back to life

I am attaching the mic preamplifier schematic for an aviation transceiver (KX165). Notice that +9V goes thru a couple of resistors to the COMM MIC IN to power the "electret preamp".
Could I power the op-amp TL071 with this +9V or should I use an external battery?
suggestions are very appreciated
Thanks

 

[Aeroplane]

Looking for an Xmas project

What is needed to run this off the existing transciever.
Aircraft radios are based on telephone the speaker only needs a matching transformer.

But you need/want the microphone to run without batteries

A bridge rectifier






Here are some how too`s

http://www.cozy1200.com/geeklog/article.php?story=20070427102533266
**broken link removed**

Air band radios and intercoms are of course designed to the GA standard, and require the microphones to look electrically like a carbon mike, and for the earpieces to have a high (about 150-300 ohms) impedance as well. They present about 9 volts at the microphone terminal to drive the preamp and mike.

Thanks again
Tony


The mike photo is from an aircraft mic that I found on the net but without the schematic, but as you can see how few componets are on the board anyone want to take a stabe at it?

 

[audioguru]

My little car is dead quiet and probably has more power than extremely noisy little airplanes.

A muffler for the engine on a little airplane doesn't weigh much. Then why don't little airplanes have a muffler?
The other day I heard a racket but the little plane was so far away that it couldn't be seen.

 

[Aeroplane]

My little car is dead quiet and probably has more power than extremely noisy little airplanes.

A muffler for the engine on a little airplane doesn't weigh much. Then why don't little airplanes have a muffler?
.

Mine does have muffler (rotax 100hp)not all have straight pipes.
It`s all about power to weight the more sound deading = weight, thin panels shake vibrate I`m sure if I add 50kg I can make it much quieter but can`t carry anyone if you drive out your driveway at 6000 rpm your car might sound a little louder that what a plane is ask to do.

 

[audioguru]

Little airplanes and even big jets use full power for takeoff where nobody is nearby to hear the loud noise.
But little airplanes cruise at low power and low RPMs and still make a racket that can be heard for miles. They sound like motorcycles and trucks that have straight pipes and no muffler.

 

[Nigel Goodwin]

Little airplanes and even big jets use full power for takeoff where nobody is nearby to hear the loud noise.
But little airplanes cruise at low power and low RPMs and still make a racket that can be heard for miles. They sound like motorcycles and trucks that have straight pipes and no muffler.

So do racing cars, it's needed to get maximum power from the engine.

 

[audioguru]

Noisy racing cars don't fly at 2km above my house. Just stupid little airplanes without mufflers. Now that there is some snow the stupid noisy motorcycles are gone.

Some street-legal racing cars have a movable plate in the exhaust to let the flames and noise out when racing but are nice and quiet on the street.

Jet planes are much quieter today. The noisy old ones are nearly all dead.