Dual-purpose voice-activated switch circuit diagram

Voice activated delay switch

Common voice-activated switches are mostly composed of discrete components. The disadvantage is that there are many components, and assembly and debugging are more troublesome. If a voice control special integrated circuit is used, the structure is simple and the operation is stable and reliable. This is because the internal structure of the integrated circuit is cleverly used to give it a delay function. As long as you clap your hands or shout, the light will light up immediately. After a period of time, the light will go out on its own. It is suitable for stairs, aisles, etc. Installation helps save electricity.

Working principle: The principle of this voice control circuit is shown in the figure below. It consists of a voice-activated sensor, a receiving amplifier, an emitter output device, a music integrated circuit, a light-emitting diode, a speaker, etc. The sound control signal generated from the outside world is converted into an electrical signal by the electret condenser microphone BM, and is coupled to the transistor VT1 through the capacitor C1 for voltage amplification. The output signal of VT1 is driven by the diode VD2 to turn on the transistor VT2, so that the power supply voltage is added to the ② pin (trigger end) of the music integrated circuit IC. The ③ pin of the music IC emits a music signal. After being amplified by VT3, it drives the speaker BL to emit loud music. Voice. At the same time, the light-emitting diodes VD3 and VD4 flash frequently with the volume of the music, like two big shining eyes of a doll. Adjusting the resistance of the potentiometer RP in the circuit can change the working voltage of BM, thereby changing the sensitivity of the sound control. Capacitor C2 is set to prevent false triggering and surge current impact.

Component selection: VT1 ~ VT3 use 9014 high-gain transistors, whose penetration current should be small, β>80. BM can choose CN-15E or other electret microphones with an impedance of 1KΩ. The music integrated circuit IC uses KD-152 and other high-level triggered music integrated chips with an operating voltage of 3V. VD3 and VD4 use light-emitting diodes with low operating voltage, small conduction current and high luminous efficiency. The remaining components are selected according to the values ​​marked in the figure, and there are no special requirements.

Installation and use:

(1) If you have a music doorbell at home, you don’t need to make a circuit casing. You can just install the control circuit as shown in the figure. (2) The electret microphone BM is installed on the outer door frame. The height depends on the height of the person. In order to keep the BM clean, you can cover it with a small piece of floral cloth and mark it with the word "voice control", which can be decorated and eye-catching.

(3) In order to prevent malfunction caused by interference from external sounds, RP should be adjusted so that BM has appropriate sensitivity. It is appropriate for the doorbell to be triggered when the human mouth is about 30mm away from the electret microphone BM.

(4) When LEDs are used for voice-controlled doorbells, only one LED is required and installed in a conspicuous place outside the door. When a person makes a sound, if the light-emitting tube displays, it tells outsiders that the circuit is working normally.

(5) If it is a children's toy, use a hollow plastic or plush toy, and put VD3 and VD4 into the two eyes. As long as the child makes a sound, the doll will flash its big eyes and sing, which is quite interesting. (6) Remove the battery when children are not playing. It is best to use a 4.7K potentiometer with a switch, which can be adjusted and switched, which can save static power consumption.