Circuit schematic as shown below, using the MC2830 voice circuit is formed. Traditional voice circuit can not distinguish between speech and noise of the input signal. In a noi
sy environment, the noise is often caused by the switch, in order to overcome this weakness. A voice circuit noise above, this is done using different speech and noise waveform. Speech waveform usually have wide variation in amplitude, and noise waveform more stable. Voice activation depends R6. Voice-activated sensitivity decreased, if R6 changes 14K to 7.0k, from 3 db to 8 db above the noise.