Sensitive Microphone Amplifier

Thread Starter

Vipul Kumar 1

Joined Oct 20, 2018
79
How can I make an electret condenser mic capsule Amplifier That Can Hear my Voice even from when i clipped it to my chest of shirt
any one give me some idea or schematic????
 

bertus

Joined Apr 5, 2008
20,182
Hello,

The LM386 is also a power amplifier.
It is older than the PAM8404 and is less efficient.

The circuit I showed in post #2 will raise the microphone level to about line level.

Bertus
 

Thread Starter

Vipul Kumar 1

Joined Oct 20, 2018
79
so any cheap and best circuit from aliexpress you want to suggest me
actually i make educational videos on youtube so i need good quality sound at cheap and best
i should be sensitive such as i should not need to amplify it futher after recording
 

bertus

Joined Apr 5, 2008
20,182
Hello,

What are you using to record the video?
Has the device a separate input for audio?
If so, what level needs that input?

Bertus
 

Thread Starter

Vipul Kumar 1

Joined Oct 20, 2018
79
I AM CONNECTING DIRECTLY MY MICROPHONE TO MY LAPTOP AND HERE IS THE SINGAL STRENGTH SCREENSHOT WHEN I SPEAK TO MY MICROPHONE FROM MY CHEST RESULT ON AUDACITY SOFTWARE upload_2019-7-19_3-13-55.png
 

Audioguru

Joined Dec 20, 2007
11,251
A microphone mounted on your chest picks up weak direct voice sounds but also picks up echoes in the room.
Use a gooseneck mic a few cm away from your mouth instead for clear and loud speach.

The Velleman kit is for a hand-held dynamic mic (coil and magnet), not for a modern electret mic. It does not power an electret mic.
The kit uses a lousy old LM358 opamp that has hiss, crossover distortion and a poor high frequency response.
The gain is probably too low for what you need.
You can plugin a modern audio opamp instead (OPA2134) and change one resistor to increase the gain.
 

bertus

Joined Apr 5, 2008
20,182
Hello,

@ebeowulf17 , The kit is not suitable for an electret microphone.
There is no bias for an electret microphone in the schematic:

K1803_schematic_for electret.png

It is likely to be used with a dynamic microphone.
To make it suitable for an electret microphone, remove R1 (100K) and connect a resistor of 10K to the powersupply.

Bertus
 

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Thread Starter

Vipul Kumar 1

Joined Oct 20, 2018
79
A microphone mounted on your chest picks up weak direct voice sounds but also picks up echoes in the room.
Use a gooseneck mic a few cm away from your mouth instead for clear and loud speach.

The Velleman kit is for a hand-held dynamic mic (coil and magnet), not for a modern electret mic. It does not power an electret mic.
The kit uses a lousy old LM358 opamp that has hiss, crossover distortion and a poor high frequency response.
The gain is probably too low for what you need.
You can plugin a modern audio opamp instead (OPA2134) and change one resistor to increase the gain.
Hello Audio Guru
So today I am going to buy all the components for the OPA2134. Can you suggest to me the best stereo schematic for the OPA2134?

Note: All upper-case converted to "normal" typography by a moderator. Please do not use all capital letters.
 
Last edited by a moderator:

ebeowulf17

Joined Aug 12, 2014
2,965
Hello,

@ebeowulf17 , The kit is not suitable for an electret microphone.
There is no bias for an electret microphone in the schematic:

View attachment 181994

It is likely to be used with a dynamic microphone.
To make it suitable for an electret microphone, remove R1 (100K) and connect a resistor of 10K to the powersupply.

Bertus
Ah, sorry about that.

I haven't done that much yet in terms of building my own audio circuits, and what little I do know about audio electronics is oriented towards the pro audio side. In that realm the mic usually includes all the necessary biasing circuitry and either uses a battery or requires phantom power. I'd forgotten about the powering/biasing scheme used for computer sound cards and such.
 

Audioguru

Joined Dec 20, 2007
11,251
You do not want to feed the 10k resistor that powers the mic directly from the raw and dirty power supply voltage, instead add a 1k resistor to the power supply voltage then connect the 10k resistor to it. Then add a 47uF filter capacitor to ground at where the two resistors are joined.
Like this:
 

Attachments

Thread Starter

Vipul Kumar 1

Joined Oct 20, 2018
79
You do not want to feed the 10k resistor that powers the mic directly from the raw and dirty power supply voltage, instead add a 1k resistor to the power supply voltage then connect the 10k resistor to it. Then add a 47uF filter capacitor to ground at where the two resistors are joined.
Like this:
thank very much sir
today i will purchase all the components
yesterday i made one circuit using upload_2019-7-20_14-40-6.png
every thing is same but opamp in my case is lm358 but the problem is when i am connecting the output and power to my laptop i am getting kind of a rfi or groudloop/humm/buzz not even connecting the mic
ref video url:
 
Last edited:
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