6421Views5Replies

Author Options:

How to connect mic to LM386 Audio Amplifier Module Board 5V-12V for Arduino Answered

HI!
I want to make a radio nany ( microphone near the baby , speaker near the mother)
 I bought   LM386 Audio Amplifier Module Board for Arduino from ebay (pic attached),  a sound sensor and a speaker. 
But I have a problem : When I conecting to the module input some audio like mobile phone or MP3 player it works, if I connecting a microphone (any) nothing....

Maybe somebody have any idea?

Will POST the device here when will work :)
Thanks! 

5 Replies

user
Downunder35m (author)2015-07-30

Try to use an old style magnetic microphone instead of a piezo or capacitor one.
Modern microphones all require filters, amplifiers and steady power supply to be able to produce quality sound.
There are quite simple circits that can be used to improve the gain from such a microphone, some as simple as a few caps and resistors, but that would only work for very low input levels.
What you have is basically Line-out level as an input and just enough power for a mall speaker.

Select as Best AnswerUndo Best Answer

user
ChrisW53 (author)2015-07-30

What you have pictured is a final stage amplifier, which
works fine with a device that already outputs a significant amplitude (power)
such as an MP3. A microphone is, for all intents a purposes, a voltage
generator but in the microvolt range; too small for the 386 to notice. You'll
need two preceding stages; a buffer and a pre-amplifier.

The microphone inputs the signal that modulates the buffer
output.

The buffer, basically a unity gain amp, provides a dynamic, unmodulated
signal to the preamp while preventing the preamp from loading the microphone. A
3904 will do.

The preamp boosts the signal to a level detectable by the
post amp (LM386). Again, a 3904 will do, but don’t forget to bias them and
insert a small value capacitor to decouple the DC component of each stage.

Select as Best AnswerUndo Best Answer

user
caitlinsdad (author)2015-07-30

http://www.learningaboutelectronics.com/Articles/M...

Is there a way to adjust the gain or input signal level to match the microphone?

Select as Best AnswerUndo Best Answer

user
AnnaL3 (author)caitlinsdad2015-07-30

the circuit is similar, to this module, I tried with the capacitor and resistor nothing work..

Select as Best AnswerUndo Best Answer

user
AnnaL3 (author)caitlinsdad2015-07-30

There is a potentiometer only to adjust the volume/gain....

Select as Best AnswerUndo Best Answer