Using kd-28 to do the voice switch circuit diagram

Posted on Mar 28, 2007

As shown is a practical voice-activated switch, A1 amplifier connected as a conventional microphone B picked up the audio control signal is amplified. After the amplified signa

Using kd-28 to do the voice switch circuit diagram
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l through C5, VD1, VD2 voltage doubler rectifier to charge the capacitor C6, when the voice signal is sufficiently large, the charging voltage of 7 feet high and A2 level, then use similar op amp amplifier A2 output high relay K is energized, its normally open contact closure turned the accused appliances. R7 and VD3 amplifier A2 self-locking, so that A2 is always 5 feet high output, ensure attracted state relay. SB is the release button, when pressed SB, 8 feet to the A2 input low, A2 flip, 5-pin output low, the relay K release. Potentiometer RP used to adjust the sensitivity level of the voice circuit. In the selection of the relay K work should pay attention to their rated voltage should be lower than the supply voltage Vcc of about about 2V.

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