>Can a speaker act as input devices to an Voice Activation circuit ?
>I want to built a Voice Activation circuit without using Mic.
>Is this possible ?
>
>Any voltage frustration from the speaker that can trigger a transistor ?

Yes you can do that. Think in terms of a dynamic microphone, or the simple
little intercoms you can buy which do exactly this. The output level may
well be very low as the sound pressure to voltage efficiency may not be as
high as a microphone.

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