BaaJ9

Kang Yijuan’s voice-activated LED lights for the school selection competition

Overview

The voice-activated LED light experiment converts the sound signal into an electrical signal through a contact microphone. The signal sent is further amplified through the triode Q1 to improve the sensitivity. Then the ON and OFF of the triode Q2 controls the on and off of the LED. Parameter selection: When there is no sound input, the transistor Q1 is in a critical saturation state, the tube Uce is very small, less than 0.7V, and the tube Q2 is cut off. When there is sound input, the pole-contact microphone has a signal output. This signal is originally a positive signal, changes in size and unchanged polarity. After being coupled by capacitor C1, it becomes an AC signal. When the negative half cycle occurs, Q1 ends and Q1 converges. The electrode voltage rises, Q2 is turned on, and the LED light turns on.

Design Files

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