9-15V Voice Control LED Level Indicator Electronic Manufacturing DIY Kit 28TC Description:Three Sections 10-Point Voice Level Indicator Kit (Blue, Green, Red 5mm LED Backlight) Features:2. Circuit PrincipleThe circuit is mainly composed of power circuit, amplifier circuit, frequency division circuit, and LED driver circuit. 1. Power supply circuit: the power output voltage is 9v-15v. D1 can avoid damaging the three terminal regulator when the polarity of the power supply is connected in an improper way. After filtering c4, the three terminal regulator L7806 will provide the whole circuit with a stable voltage of 6V. 2. Amplifier circuit: MK1 electret microphone transfers the resulting sound into an electrical signal, which will be amplified twice by Q1 and Q2. At this time, the UR1 can adjust the size of the Q2 signal to adjust the sensitivity of the entire circuit. 3. Frequency division circuit: three frequency division circuits are added to indicate the electrical level at different frequencies because it is equipped with three sections of LED indicator in a separate way. VR2, VR3, and VR4 are used to adjust the sensitivity of the LED indicator at different frequencies. The beep from the three different frequencies can be distinguished according to the different capabilities of the C6, C10 and C11. The collectors Q4, Q5, and Q18 can obtain three different frequencies and voltages when divided and amplified by a diode and a transistor. The voltage level depends on the volume of the sound from the outside. 4. LED driver circuit: there are 9pcs 1N4148 diode in each frequency. If the sound is louder, higher voltage will be obtained through the Q4, Q5 and Q18 connector, and more 1N4148 will start working. Then more LEDs can be lit. Specifications:Kits Model: SAL-30Working Voltage: 9-15V PCB Measurements: 161x4 2mm/6.34x1.65" Quantity: 1 Set Note: Please allow 1-3mm error due to manual measurement. Pls make sure you do not mind before you make a bid, due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Non-retail Package Package Included:1x9-15V Voice Control LED Level Indicator Electronic Manufacturing DIY Kit