0.Shocked ! The owner of Wanfen UP actually plagiarized other people's projects!

This project is actually a castrated youth version of the clone project . The clone project will have more functions, so stay tuned.

If nothing else, there should have been an accident (referring to the fried board).

1 Introduction

There are many pickup light products now, and I have bought some of them

However, these come with some problems, big and small.

First of all, from a consumer point of view, these are products made of LED lights, which are very dazzling when shining directly into people's eyes. I bought them and used them several times without turning them on. I really can't stand the LEDs shining directly into my eyes. Feel.

Secondly, I analyze from the perspective of a hardware engineer. These products are collected from the microphone through the ADC of the MCU, and then the MCU controls the RGB lights, so there must be signal loss. In the instant, the loud sound will not change, but some subtle changes will occur. The sound light is on again. Although it is not necessarily a sampling problem, it may be because the chip has dynamic compression and noise reduction processing, but these are some of the problems that exist in the actual experience of these products.

Therefore, this project adopts the form of pure analog circuit to make a non-glaring pickup meter.

The final video shows a comparison between the two, so seeing is believing and let’s see which one looks better!

2. Introduction

It uses the BA6138 dual-channel VU meter driver chip, connects the VU meter with dual microphones, and swings the meter head along with the ambient music. The swing frequency is adjustable, and it has a power switching circuit, and a lithium battery is optional. The charging chip is the commonly used TP4056 chip, the boost chip is SX1308, and the microphone is a ready-made MAX4466 module.

3.Features

• Pure analog circuit design, no ADC, DAC losses
• Low production cost and simple circuit
• Dual-channel design of left and right dual microphones, the channels are independent and do not interfere with each other
• Gain adjustable
• With light drive circuit
• Optional welding battery, battery life can be selected by yourself
• There is a power switching circuit, which cuts off the battery power supply during external power supply and switches to external 5V power supply and charges the battery at the same time (UPS-like circuit)
• Supplied with housing

4.Principle

4.1 Charging/boosting integrated circuit

I actually use this circuit a lot, in access control or other low-power projects, including the TP4056 chip that charges a lithium battery, and the SX1308 chip that can boost the lithium battery, but this time I did a little bit more The improvement is to add a PMOS. When the charging port TYPE-C 5V has power, the charging chip will charge the battery, Q2 will cut off at a high level, and the battery current will not flow into the boost chip, and can only be used by the D1 diode TYPE- C of 5V to extend battery life.

When TYPE-C does not have 5V, Q2 is turned on at a low level, and the boost chip is powered by the battery.

This principle is actually the same as the idea in the ESP32 Bluetooth FM speaker I made before , which is also controlled by PMOS, but that PMOS needs to be dedicated and has high power, which can also be purchased. However, this time I used AO3401, which is a cheaper and low-power PMOS.

SX1308 boosts to 12V by configuring the resistor.

If you don't plan to use battery power and just want to use USB5V, you don't need the charging circuit and MOS tube.

4.2VU meter drive circuit

The original design intention is to use two MAX4466 modules to obtain the audio of the left and right channels, so it is normal for the left and right meters to swing differently, and this is the effect. If you don't like the dual-channel design, you can connect the outputs of the two MAX4466 modules and install only one during installation, but this is not recommended.

The BA6138 chip is used to specifically drive the VU meter, and the left and right microphone modules obtain the ambient sound input.

Adjusting the resistors and capacitors here can adjust the pointer drop and delay effects. The above parameters are the best results.

The power-on delay circuit is used to prevent the meter pointer from bottoming out at the moment of power-on.

4.3 Buck circuit

It is relatively simple, just use AMS1117-5.0V to step down 5V from 12V to the MAX4466 module.

5.Code

No code, pure analog circuitry.

6. Adjust the balance of the left and right MICs

When purchasing the MAX4466 module, since I don’t know where the potentiometer is after buying it, the left and right channels will have errors and imbalances no matter how they are adjusted, so the balance needs to be adjusted.

As shown in the picture above, remove the potentiometer.

Then, as shown below, weld a 16k resistor to the original two legs of the potentiometer.

The resistor is recommended to be 16k or 18k 1% resistor. It is not recommended to use a resistor that is too large or too small.

The resistance of this value will not be too loud or too quiet, and it will be within a suitable range.

7. Housing/Assembly

Draw using SOLIDWORKS, see assembly 3.SLDASM for the source file

Required parts:

The shell is divided into two parts

There are files that can be printed directly without SOLIDWORKS

See 1.STL 2.STL

It is recommended that the wiring should not be too thick, so as not to affect the assembly, and the internal space is limited.

The shell of this castrated youth version of the pickup meter can only be 3D printed, not acrylic. Because the PCB is too small to fit the VU meter, and the charging port is too far away from the case if it is enlarged.

The upgraded pickup meter (clone) will draw 3D printed and acrylic shells, use a more advanced and larger VU meter, and may try to use the professional version of Lichuang EDA 3D shell drawing and panel drawing functions (JLC can you let me pick up the wool# sinister smile). Stay tuned!

8.VU meter

This case is for this company ’s VU meter: first, it is smaller in thickness and volume, second, it is cheaper, and third, the backlight does not distinguish between positive and negative .

If you want to use other meters by yourself, please confirm the parameters: 0-500uA, internal resistance 650 ohms!

Otherwise, you need to manually determine the resistance parameters to adjust the left and right balance in Section 6.

9. Summary

Finally, I would like to thank @武利研究中心for the reference circuit. I modified and expanded it based on his circuit. You can pay attention to this big guy.

You can also follow my channel @__Aknice

The production video will also be released on station B in a few days, mainly waiting for the shell to be drawn and printed and various materials to be improved. stay tuned!

The effect is like a video. Please turn on the sound to watch. Problems such as recording equipment and video compression bit rate may make the audio and video appear to be out of sync, but it is actually real-time.

Suppression tool: Format Factory 60FPS <50MB.

Audio and video recording equipment: Redmi K40 1080P_60FPS.

Speaker: BOSE SOUND BAR.

Music: Liyue Liyue - Chen Zhiyi/HOYO-MiX; Qianqian Quege - Priscilla Chan; Mirai は风のように - Liella! (TV animation "Love Live! Superstar!!" ending theme)

It is obvious from the comparison that the VU meter really swings with the rhythm of the music, especially songs like Liyue with various instruments (because each instrument has a different frequency response, especially the second half of the piano part, the light bar cannot be recognized at all) Completely beat LED RGB light strips (two identical light strips with the same parameters will not be synchronized)!