Help Designing Circuit

Hello All,
I'm new the the forum, and I was hoping for some help.
I am trying to design a circuit, but I don't know where to start.
I have a device that emits a high pitched, loud sound at random times.
I was hoping to create a device that could turn on an LED when the sounds occurs. The problem is that I can't open the device, so I can't tie directly into the speaker.
I was thinking I would need to have a microphone, filtered in some way to only trigger the LED when the specific frequency is detected.
My final issue is that it needs to be as small as possible.
I was hoping you could help me out.
Thanks all

Put any of these very close to the noise source.

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Sound Operated / Sound Activated Electronic Circuits
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Thank you Flat5
Do you know if there is any way to have the sound trigger isolated to a single frequency?

horwichg said:

Thank you Flat5
Do you know if there is any way to have the sound trigger isolated to a single frequency?

Click to expand...

The ubiquitous 567 tone decoder is a popular device for singling out audio with a single frequency. It will drive an LED directly (20 mA). Link below:

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