http://www.national.com/ds/LM/LM3916.pdf
page 12
FIGURE 7. Full-Wave Average Detector to VU Meter Specifications

Question is what is C2?
says 2.0 or 1.0 but that cant be farads

 

An LM3914 has linear steps like a voltmeter.
An LM3915 has logarithmic steps to measure sound or light levels.
You talked about a mic but its output is only a few mV but an LM39xx circuit needs volts of input. Use a mic preamp followed by a peak detector circuit.

 

what is C2?
says 2.0 or 1.0 but that cant be farads

It's in uF (microFarads).

 

Thanks sgt.

An LM3914 has linear steps like a voltmeter.
An LM3915 has logarithmic steps to measure sound or light levels.
You talked about a mic but its output is only a few mV but an LM39xx circuit needs volts of input. Use a mic preamp followed by a peak detector circuit.

well then that would be figure 6. But would i really need to use a mic or could i just feed the pc output into the Precision Full-Wave Peak Detector or are the op amps going to step up the voltage too much?

 

have you ever heard MONOTONIC. look it up.

 

The minimum input for an LM3914 to light the 1st LED is 0.125V. A mic is 1/10th that or less so it won't work without a preamp.

Your Mickey Mouse breadboard is picking up interference. Use a pcb or stripboard.