Re: sound detector amp/electret mike amplifier

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sound detector amp/electret mike amplifier

Posted by: andrew ()

Date: June 26, 2003 09:38PM

parts:
U1 LM741 op amp ic
R1 1 megohm resistor
R2, R3 6.8k ohm resistor
R4 1k ohm resistor
C1, C2 0.47uF ceramic capacitor
MIC1 electret condenser microphone

all resistors are 5 or 10 percent tolerance, 1/4-watt
all capacitors are 10 percent tolerance,
rated 35 volts or higher
this circuit amplifies the output of a regular electret condensor microphone quite nicely.. adjust sensitivity by turning R1

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Re: sound detector amp/electret mike amplifier

Posted by: Harry ()

Date: November 28, 2003 09:41PM

How can Q1 get any DC bias? It needs base current to operate!

It will also have pretty bad distortion with no emitter resistor.
confused smiley

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Re: sound detector amp/electret mike amplifier

Posted by: luppy ()

Date: December 10, 2004 12:14PM

One enquiry, a typical electret condenser mic that i have came across with has only two connections.

how do i know where to connect the capasitor(c1) 0.47F, assuming that the two connections are connected to gnd and vdc 5v.

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Re: sound detector amp/electret mike amplifier

Posted by: matt ()

Date: August 21, 2005 07:12PM

i tried building this circuit, and i'm only hearing a buzz. no sound from the mic is coming through to the output, and playing with the potentiometer seems to have no effect.

any clue what the problem could be?

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Re: sound detector amp/electret mike amplifier

Posted by: Al ()

Date: October 28, 2005 01:21PM

Don't forget that you need to BIAS the Base of the 2222. Try a Voltage divider between to set VBase to about 2V. Of course you'll see a really huge gain -- But hey, drop it by adding an emitter resistor. Av = RC / RE

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			Home Forum!! *Robotics Projects:* Smallbot *Electronics Projects:* SMT Reflow Serial Multiplexer *Project Log:* Current Projects My Bench Equipment				Amplifiers : Reconn's World Forum Attention! If you would like to post, but don't want to create your own account, use login:guest password:rw -- Enjoy! Goto Topic: Previous•Next Goto: Forum List•Message List•New Topic•Search•Log In•Print View sound detector amp/electret mike amplifier Posted by: andrew () Date: June 26, 2003 09:38PM parts: U1 LM741 op amp ic R1 1 megohm resistor R2, R3 6.8k ohm resistor R4 1k ohm resistor C1, C2 0.47uF ceramic capacitor MIC1 electret condenser microphone all resistors are 5 or 10 percent tolerance, 1/4-watt all capacitors are 10 percent tolerance, rated 35 volts or higher this circuit amplifies the output of a regular electret condensor microphone quite nicely.. adjust sensitivity by turning R1 Options: Reply•Quote Re: sound detector amp/electret mike amplifier Posted by: Harry () Date: November 28, 2003 09:41PM How can Q1 get any DC bias? It needs base current to operate! It will also have pretty bad distortion with no emitter resistor. Options: Reply•Quote Re: sound detector amp/electret mike amplifier Posted by: luppy () Date: December 10, 2004 12:14PM One enquiry, a typical electret condenser mic that i have came across with has only two connections. how do i know where to connect the capasitor(c1) 0.47F, assuming that the two connections are connected to gnd and vdc 5v. Options: Reply•Quote Re: sound detector amp/electret mike amplifier Posted by: matt () Date: August 21, 2005 07:12PM i tried building this circuit, and i'm only hearing a buzz. no sound from the mic is coming through to the output, and playing with the potentiometer seems to have no effect. any clue what the problem could be? Options: Reply•Quote Re: sound detector amp/electret mike amplifier Posted by: Al () Date: October 28, 2005 01:21PM Don't forget that you need to BIAS the Base of the 2222. Try a Voltage divider between to set VBase to about 2V. Of course you'll see a really huge gain -- But hey, drop it by adding an emitter resistor. Av = RC / RE Options: Reply•Quote Goto: Forum List•Message List•Search•Log In Array Sorry, only registered users may post in this forum. Click here to login This forum powered by Phorum.