# Sound Level Monitor

Discussion in 'Homework Help' started by mufcdanny, Jul 9, 2009.

1. ### mufcdanny Thread Starter New Member

Jul 9, 2009
5
0
Hey, I am new to this site.
I was wondering if anyone could help with my project, I had missed alot of my lessons due to illness and I can not find the solution in my notes. I have attached a file which I have to design. I just need help desining the circuit. I can work out the vaules for my self. I'm just not sure how to lay out the circuit.

Any help would be greatly appriacted.

Many Thanks
Dan

File size:
284.5 KB
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2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
282
What have you been able to do? Problems with the microphone preamp, or calculating the gain for the second stage?

Apr 5, 2008
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4. ### mufcdanny Thread Starter New Member

Jul 9, 2009
5
0
Im just struggling on how to design the circuit. I have a few caculations, but seeing where the companants go will help me calculate the rest. I'm having a serious mind blank.

Thanks

Apr 5, 2008
15,648
2,347
Hello,

Can you show the calculations?
As I understand you want to convert the calculations to a circuit.

Greetings,
Bertus

6. ### mufcdanny Thread Starter New Member

Jul 9, 2009
5
0
I have misplaced my calculations but I had a input resistor of 1Kohm. Feedback resistor of 20k.
I have -68.5dB/v aswell. I will try to find them out.
I also have 20,000,000 gain bandwidth product wrote down.

Thanks for getting back to me
Any help is greatlty appreiacted

Last edited: Jul 11, 2009
7. ### millwood Guest

you are asked to design a balanced preamp, with a frequency response up to 20khz, that when connected with a microphone (1kohm output impedance, and -54.5db/p sensitivity), it will trigger the led when the microphone sees 80dbl sound level.

simple as that, .

8. ### mufcdanny Thread Starter New Member

Jul 9, 2009
5
0
I have sort of designed the pre amp. Im not sure about the component values, does anyone know what calculations I should be using so I can check. Thanks
Dan

Last edited: Jul 21, 2009
9. ### mufcdanny Thread Starter New Member

Jul 9, 2009
5
0
Also how much gain is 10Hz to 20Khz?

10. ### beenthere Retired Moderator

Apr 20, 2004
15,815
282
That is not gain, that is frequency response. Gain is an increase in voltage, current, or power.