Adjustable music rhythm light (verified) Rhythm light spectrum light

The power consumption of the 12V power supply is only 0.2W (tested in the video). The project is mainly divided into three parts:
 
1. Power input part:
Considering the inconvenience of using and charging the 12V battery, the project uses the commonly used TypeC power supply, but because LM3915 usually A 12V power supply is required to provide sufficient LED voltage drop, so a dcdc boost chip is used. The project uses the domestic sx1308 chip (a few cents), and changes the boost voltage (maximum 24V) by controlling the resistance value of R7. The boost calculation formula is: VOUT=[(R7/R5)+1]*0.6V (R5 is usually 10K, When R7 is set to 191K, VOUT is about 12V)
2. Sound collection part:
Use a commonly used microphone on the market (commonly known as a microphone head) to collect sound signals. The general principle is that the microphone head is an electret with a certain amount of permanent charge Q. Different sounds The large and small sound signals cause the internal film to vibrate, causing the distance d between the plates to change. According to C=εS/4πkd, the capacitance C changes, and Q=CU, the charge Q remains unchanged, so a changing voltage U is produced, as shown in the figure C6 is the filtered DC voltage input. Because the filtered DC voltage is 12V, aluminum electrolytic capacitors with higher voltage resistance are usually used.
The collected sound signal is too small to be driven directly, so audio amplification is required, using the integrated operational amplifier LM386. LM386 can also amplify the audio signal from the microphone and drive the speaker/speaker. Interested readers should do their own research. According to the chip manual, the size of the resistor between pins 1 and 8 determines the final gain. Add a sliding rheostat to adjust the amplifier gain to adjust the audio light sensitivity.
 
3. Music indication part:
Using the existing LM3915, LED1-LED10 pins are connected to 10 LED lights. Usually, a current limiting resistor needs to be added, but if two LEDs are connected in series to each pin to increase the voltage drop, the current can be reduced. Pin 9 is the mode selection terminal, high level is column display mode, and low level is dot display mode.
This chip can be cascaded to form a larger music level light, or the audio signal corresponding to each LED can be band-pass filtered to change the original volume detection into the sound spectrum detection. Interested readers please Do your own research. For an introduction to this chip, please check out this video, which is very detailed: Quickly get started with the LM3915 level indicator control chip and make an audio level indicator [This is how the IC turns out]_bilibili_bilibili
Finally, here are two physical pictures and Demo video: