CIRCUIT analysis

KCHARROIS

Joined Jun 29, 2012
311
I dont see why the led wouldnt turn on. The microphone does produce a small current. But since you have 2 transistors the gain would should be high enough to give enough current for your LED.
 

BillB3857

Joined Feb 28, 2009
2,571
Is this a homework assignment? If so, let us know what you think and why. We'll be happy to help you learn, but not happy to do your homework for you.
 

Thread Starter

amit080391

Joined Jul 13, 2012
5
sir i think it will work because when input from mic goes to bjt gate terminal , bjt will operate and other bjt will also work and we will get output and led will glow ....!!!
 

bretm

Joined Feb 6, 2012
152
My understanding of electret microphones is that they are used for the voltage they provide directly, instead of being used to modulate at existing current flow like in the circuit shown. So that part is weird.

But the LED would light even if the microphone were ripped out of the circuit. In that case, Q1 would be cut off, so Q2 would get 9mA of base current and would turn on hard.
 
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Audioguru

Joined Dec 20, 2007
11,248
I think that the electret mic and 330 ohm resistor will turn on the first transistor all the time so it turns off the second transistor all the time. An extremely loud sound might make the LED blink.
 

WBahn

Joined Mar 31, 2012
30,071
Is led will glow or not??
IS this circuit correct ??
when we speak in microphone which is connected
ANSWER FAST
Whether the circuit is correct depends entirely on what the circuit is supposed to do, which is not stated anywhere. Don't make people guess.
 

absf

Joined Dec 29, 2010
1,968
KCHORRIOS said:
If you always want the LED to always be on do it this way like my schematic. I just moved the mic and coupled it to the transistor base.
I think the 220 ohm for biasing Q1 is too low. It would make Q1 saturate.

But the mic should work well under this condition.

Allen
 
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