Moveable 15-Watt PA System With Battery Administration

Many mini digital modules can be found available in the market for offering fast plug-and-play options. We are able to use a few of these modules to make a low-cost, moveable, 15W public tackle (PA) system that features a battery administration system (BMS).

Building and dealing

Fig. 1 exhibits the connection diagram of the undertaking, which makes use of three major modules together with three lithium-ion batteries (B1, B2, and B3). There are the next major blocks on this undertaking:

1. LM386 amplifier module, which acts as preamplifier
2. TDA2030 audio amplifier module, which acts as an influence amplifier
3. 3S 10A, 12V 18650 lithium-ion battery charger safety module
4. Three 3.7V 18650 lithium-ion battery banks
5. 12V DC energy provide

LM386 audio amplifier module

It’s a miniature module with an onboard LM386 chip (700mW analogue enter, class-AB audio amplifier). It’s a easy operational amplifier (op-amp), which is greatest suited to low-power audio amplification functions. Fig. 2 exhibits the amplifier module, which has a achieve of round 200. It has an on-board 10-kilo-ohm variable resistor to regulate the achieve. There’s an on-board energy indicator LED too.

The module has a generic working voltage between 4 and 12V DC and an on-board potentiometer to extend/lower the amount. It has low static energy consumption and quiescent present of about 2mA that’s appropriate for a battery-powered gadget. It has 4 pins, particularly, VCC, Vin, audio GND, and provide GND. As a result of its excessive achieve and low distortion, the board can be utilized as a preamplifier. This helps to attach the module simply to a microphone.

A dynamic microphone is used right here, which acts as an enter to the preamplifier module. A dynamic microphone is a transducer audio gadget that produces sound by a shifting electrically conductive diaphragm and a everlasting magnetic construction. Dynamic microphone has easy benefits like plug and play, output electrical sign that’s immediately proportional to the enter voice, and electrical voltage output of the order of some millivolts. Whereas a condenser microphone wants just a little additional circuitry to drive the preamplifier module. The output of the preamplifier module is related to TDA2030A audio amplifier module (Fig. 3).

TDA2030A audio amplifier module

This module relies on the well-known TDA2030A audio amplifier IC and gives 18W energy output with very low harmonic distortion. It has an working voltage vary of 6 to 12V with 10-kilo-ohm adjustable resistance to regulate the amount and an onboard LED energy indicator. A 15W speaker can be utilized to connect with the output energy amplifier. A 6.5mm mono microphone feminine socket can be utilized for connecting the microphone to the preamplifier.

18650 BMS module

To make the system moveable, the 18650 mannequin lithium-ion 2500mAH, 3.7V rechargeable batteries are used. The batteries have a excessive vitality density and low self-discharge. Lithium-ion batteries could be recharged a whole bunch of occasions and are extremely secure. This gives higher energy effectivity as a single cell has longer cost retention than different rechargeable battery sorts.

Nevertheless, deep discharge makes the voltage of lithium-ion cells fall under a sure degree the place these can’t be recharged additional and change into ineffective. To keep away from this, we use the 3S 10A, 12V 18650 lithium battery charger board safety module (Fig. 4). Right here, 3S stands for the three 18650 batteries’ sequence mixture, 10A stands for the utmost discharge present restrict, and 12V stands for the working voltage.

The BMS has an overcharge detection of 4.25V and overdischarge detection of two.5V per cell. The batteries and the BMS module are related as proven within the connection diagram.

A 12V, 1A SMPS charger could be related for charging and powering up the circuit. Select an acceptable field to suit all of the modules, the speaker, and the batteries. The creator’s prototype is proven in Fig. 5.

Precautions

Verify the polarities of the modules earlier than making connections. By no means brief a battery. Lithium-ion batteries are extremely delicate to excessive temperature, so keep away from publicity to excessive temperatures. Preserve a ways between the mic and the modules to keep away from suggestions echo noise.

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Ok. Murali Krishna works as junior engineer at BSNL, Rajahmundry, Andhra Pradesh. He’s an electronics fanatic, circuit designer, and technical author