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'[EE]: Buzzer sound recognition'
2002\08\15@083629 by atric_Anveg=E5rd?=

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Hi,

I am currently evaluation different options to be able to recognice a buzzer sound from a speaker. For different reasons i would prefer to do this with passive electronics only. Does anyone have any experience with this kind of problem? It is only one buzzer signal that I need to detect. The frequency is unknown at the moment... As an output from the passive electronics I would like to have a change in the logic voltage level. Since I am really not an expert (by far) on analog electronics I have really only found one suggestion that I think might work: Band pass the speaker signal at the buzzer frequency and than integrate the signal to be able to accept the signal after a certain amount of time.

Regards

Patric Anvegård

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2002\08\15@084304 by Alan B. Pearce

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>For different reasons i would prefer to do this with passive
>electronics only. Does anyone have any experience with this
>kind of problem? It is only one buzzer signal that I need to
>detect. The frequency is unknown at the moment...


Check out the NE567 tone detector chip. I believe National Semiconductor
still make it. By setting external component values you can set up the
frequency to detect.

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2002\08\15@153655 by Peter L. Peres

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Use a tone detector and a microphone preamp (can be bandpass at the same
time). Tone detector can be 567 or CD4046, preamp LM358 is enough. Is the
buzzer the loudest source around ?

Peter

On Thu, 15 Aug 2002, Patric Anvegård wrote:

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2002\08\15@180824 by Kevinhoward

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Is the buzzer a constant frequency?

Does this frequency have to be detected in a quiet or noisy environment?

What is the distance from the buzzer to the loudspeaker?

What type of loudspeaker are you proposing to use?

Regards

Kev

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2002\08\16@005446 by Bill & Pookie

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could you use a second buzzer on the receive end
as a filter?  A 40k transducer will oscillate when
in the presences of 44k audio.  and maybe some of
the pezio buzzers will do the same.  And could the
same be done with two mechanical buzzers by
inputting the signal from the speaker (rather than
the audio) to the remote buzzer?

Bill

{Original Message removed}

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