In the design of voice control circuit, if face how to convert sound into electrical signals to the topic. Voice control circuit design, the requirement of voice signal sensitivity cannot be too low. Also cannot too tall, too high or too low voice control circuit are difficult to achieve good control.
Sound signal sensitivity is best can receive such as people, whistles, clap the externalized selves loosed and feet on the floor, etc. Can convert this kind of voice signal into electrical signal has a variety of sound sensor, which can choose small tape recorder on the commonly used electret microphone receives the sound into electrical signals, the transition of voice signal into electrical signal.
Electret receiver converts the electrical signals generally weak, convert electrical signals must be properly enlarge to play a control function. Optional circuit has a power amplifier circuit, operational amplifier circuit, differential amplifier circuit, etc., generally choose the op-amp circuit is better.
Op-amp circuit can improve the output voltage of the signal, zero drift, reduce the distortion, but will increase the size and cost of circuit. Generated signals, realize voice control function is relatively easy, can be used only to transistor amplifier circuit to amplify the electret microphone to produce electricity for number, trigger controller make the circuit conduction or globe, not only simplifies the circuit structure, make it easier for voice control circuit design, and are more likely to achieve sound control function. The circuit design of components of the demand is higher, especially semiconductor devices must guarantee the high sensitivity, precision electronic components parameters of stability, the circuit can work efficiently, normal play the function of circuit.