urgent

Thread Starter

engy

Joined Mar 27, 2009
7
i tried this circuit but unfortunately it didn't work .... i replaced the meter with led array workin with lm3915,at all the leds doesn't change they lighted uniformly plz tell me is this circuit ir wrong ? ? can i try it with proteus and if it's yes then what type of input since there's no mic found in the program.....
 

CDRIVE

Joined Jul 1, 2008
2,219
I'm sorry! I placed my fingers on my monitor and tried a Vulcan Mind Meld but no go. I guess you're just going to have to post the schematic. :rolleyes:
 

CDRIVE

Joined Jul 1, 2008
2,219
Well, was it working with the meter? The LM3915's input pin is going to be referenced to ( - ) GND, which the meter isn't.
 

CDRIVE

Joined Jul 1, 2008
2,219
Since Audioguru figured it out - is your microphone an electret type? This won't work otherwise.
While the circuit appears to employ an electret mic I don't believe that a dynamic mic wouldn't work there. R1 is 10K, so it's doubtful that it would have that much effect on a 1K dynamic element. I could be (CYA) wrong though. :)
 

Thread Starter

engy

Joined Mar 27, 2009
7
the mic used is electric mic,,,,i connected the (+) of the meter with the input of the lm3915, the circuit worked but i faced a problem which is ther're no variation in the led's brightness,, i think that this variation must be done by receiving different sound intensity and then variation in output volt.
may be the mic connection is wrong.... what can i do ? ? ?
 

Audioguru

Joined Dec 20, 2007
11,248
The + of the meter in the circuit has a continuous DC voltage. Your LM3915 circuit displays how much DC voltage.
You need to use a resistor to ground at the input of the LM3915 then a coupling capacitor for the signal.
I sketched the correction but the LEDs will look like a dim blur unless you make the "half-wave peak detector circuit" that is shown on the datasheet of the LM3915.
 

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