{"id":5449,"date":"2018-10-03T22:22:58","date_gmt":"2018-10-03T16:52:58","guid":{"rendered":"http:\/\/nuclearrambo.com\/wordpress\/?p=5449"},"modified":"2024-10-04T12:54:43","modified_gmt":"2024-10-04T07:24:43","slug":"a-simple-voice-detector-circuit","status":"publish","type":"post","link":"https:\/\/nuclearrambo.com\/wordpress\/a-simple-voice-detector-circuit\/","title":{"rendered":"A simple voice detector circuit"},"content":{"rendered":"\n

Voice detector can find it’s use in voice-activated circuits. For example, triggering a transmitter or enabling a speech processor and so on. At the end of this blog post, we will look at one such application. A voice detector is a circuit which will either give a logic 0 for the presence of sound and logic 1 for an absence of sound or vice versa. Without further wasting more words, let us understand the signal we are dealing with.<\/p>\n\n\n\n

Nature of the signal<\/h2>\n\n\n\n

Voice, if converted into electrical signal, will show the voltage that alternates above and below zero volt line. In other words, it is an AC signal.<\/p>\n\n\n\n

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Voice signal on the oscilloscope<\/figcaption><\/figure>\n\n\n\n

Using a simple peak detector circuit will convert the AC nature of the signal into a DC signal. The DC level will be directly proportional to the amplitude of the voice. We also need to take care of the bandwidth of the voice detector because a higher bandwidth will result in a higher noise floor which will cause false triggering. A low pass filter designed for 5kHz should be more than sufficient.<\/p>\n\n\n\n