simple circuit design

Jun 19, 2007 4 Replies
E

I am looking for someone to prepare for me a fairly simple circuit design with all components and values specified. I will be happy to pay any reasonable amount for this service. what I want is a device which will accept the audio input from a condenser microphone, and pass it through a low-pass filter which will only pass frequencies up to 12 Hz with a fairly sharp cut-off. The filtered output should be fed into a device such as an LED array which will approximately reflect the dominant frequency in the range 0 to 12. Ideally, the voltage supply will be 6V.



If this is insufficient information, please get back to me.



Eddie



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M

Since this sounds like a Fourier transform, you may also want to post on comp.arch.embedded.

My first worry would be that the condenser microphone doesn't have any useful sensitivity at frequencies that low.

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L

Especially at the low end, 0Hz.

Actually, at those frequencies, you might just be satisfied with counting the blinks.

RL

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B

There are microphones that are perfectly capable of picking-up frequencies as low as 0.1 Hz They are available, sold as measuring microphones. When your budget is not sufficient, a more conventional microphone can be modified to do so. This microphone needs to be a omni-directional type condensor mic. These are pressure-sensitive microphones. Electronics needs to be modified for DC-coupling. And when modifying, the low-pas can be done at-once.

But please be aware that this conventional microphone will still be a studio-quality type costing $ 1000.- or more

Bob

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