Hey, could someone explain what's going on in the upper left of this schematic? The mic only seems to be connected to ground.

 

Hey, could someone explain what's going on in the upper left of this schematic? The mic only seems to be connected to ground.

It is connected as it should be, bias (red) wire connected to VCC, output going into the 741's - input, and ground....


My .02

 

Thank You. A little confusing seeing an unconnected pin.

 

A 741 opamp is much too noisy (hissss) to be a mic preamp.
Most electret mics have only two wires, the signal and power pin and a ground pin. A three wire electret mic is rare.

 

What is the purpose of C2, Q1, and R4? Whatever it is, it won't work.

 

Huh? Oh Dear God. Tell me it isn't so. Rare as in ... ? jackalope? what. All the electret mic's I have are 2 pin. Ron, Check ecelab.com, they have the copy/original there - though without the word 'red'. I'm just trying to use an op amp to boost mic signal to blink a light. I.E. led. Need help; that's why I'm here, you awesome folks you are.

 

Ron, Check ecelab.com, they have the copy/original there - though without the word 'red'. I'm just trying to use an op amp to boost mic signal to blink a light. I.E. led. Need help; that's why I'm here, you awesome folks you are.

When you provide a link, try to be more specific. Ecelab has hundred of links on their main page.
And it wouldn't matter if it were on God.com, it won't work without a resistor or diode (anode to GND) from the base of Q1 to ground. A resistor in series with C2 would be a good idea also.

 

Thanks Ron,
http://www.ecelab.com/circuit-sound-detector-1.htm
Just looking for help here.

 

Thanks Ron,
http://www.ecelab.com/circuit-sound-detector-1.htm
Just looking for help here.

Here's a place to start:
Change the power supply to 9 volts.
Add a 1 megohm resistor from the base of Q1 to ground.
Add a 1k resistor in series with C2.
Change R4 to 680 ohms, and add an LED in series with it.

 

Thank You Very Much Ron. I will use your advice.

 

Is it possible to swap the lm741 with a standard dual op amp like the 4580dd jrc?

 

Is it possible to swap the lm741 with a standard dual op amp like the 4580dd jrc?

That should work. Disable the unused op amp if you're not using it. One way to do this is to connect the + input to the junction of R2 and R3, and the output to the -input.

 

Thanks Ron, will give this a shot.