Make a circuit that send out digital high when sound gets over certain level, how?

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I'm working on i project, but i need a circuit that gives out a digital high when the sound gets above a certain level. I was thinking of using a op-amp and connect it via an trimpot to a and gate to clean out the signal. This may work(or not) But is there anyone out there with a better solution?

Some hints or chematics would be greate!
 
Use a comparator circuit. You set a reference level for your audio and when that level (Ref) is exceeded the output will toggle. What you are not saying is if the level exceeds the refrence then what? Do you want the comparator to drive a latch requiring a reset or just follow the input?

More details would help. Is this an audio signal and where is it from? Just sound? Then you need a mic circuit (pre amp) to drive the comparator circuit.

Ron
 
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Thanks for the tip so far.
The plan is to use a mic, then when sound level reach Ref i'l get a digital high, the plan was then to use a 4538 (Dual Retriggerable Precision Monostable Multivibrator) to keep that signal high for a serten time for a mcu to read it.

Hope that clarifys it a little more
 
If you use a diode to rectify the peak signal into a capacitor with a parallel resistor to ground, and the comparator input connected to the capacitor voltage, then the peak voltage can be held as long as desired as determined by the RC time constant.

You likely wouldn't need to add a one-shot with such a circuit.
 
I think you need to "average" the sounds you pick up because many loud sounds are "percussive" and occur for only a moment. You probably want to detect only loud voices or loud continuous machines.
 
audioguru said:
I think you need to "average" the sounds you pick up because many loud sounds are "percussive" and occur for only a moment. You probably want to detect only loud voices or loud continuous machines.
Click to expand...

It is acually the peak sounds that I am interested in. The circuit is to detect rifle shots and the time between them.
 
A rifle shot noise is extremely fast so a very fast opamp peak rectifier circuit must be used.
Are you trying to show gun people how soon they will be deaf?
 
An electret mic needs to be fed about 0.5mA from a filtered voltage source to power its Jfet impedance converter. It has a low output level so it needs a preamp circuit.
 
<Off Topic>

Don't shoot the duck.. It's his amplifier.
Click to expand...

I put a round through one of my sky screens once for my chronograph.

</Off Topic>

That amp posted could work maybe and eliminate several parts. Pretty slick!

<EDIT> On second thought there might be a need for a gain pot. If this project is used for multiple caliber gun shots the "bangs" won't be the same audible levels. I guess maybe if there is no other background noise it would work but if at a range or if there is mixed background noise there may be problems. Things like false triggering on noise levels not wanted. </EDIT?

Ron
 
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Thanks ronv! I tested the circuit in Multisim and it looks real nice, worked real good with my computer mic. I'l have to look trough my stuff to see if I got the parts for a test build then.

Reloadron: It's for use on my private shootingrange so there is only one person shooting at a time.

Thanks alot folks, I'l probably post a update when i got some test results.
 
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