The Wireless Audio Amplifier project addresses the growing demand for audio amplification by focusing on wirelessly transmitting and amplifying audio signals. This is achieved through the utilization of the VTF-108 Bluetooth module in conjunction with the audio amplifier IC TA8210AH.
The Bluetooth module has the capability to establish connections with a variety of devices, including Hi-Fi equipment, mobile phones, and MP3 players. In this setup, audio sources like mobile phones serve as the transmitter unit, while the Bluetooth module, audio amplifier, and speakers together constitute the receiver or wireless speaker unit. The receiver unit enjoys the flexibility of being positioned anywhere within Bluetooth range, allowing for cable-free mobility. The amplifier within the receiver unit plays a pivotal role in enhancing the audio signal.
This innovative design finds applications in various settings, including four-wheel vehicles, residences, seminar halls, and more. The author’s prototype is depicted in Figure 1 as a reference.
Circuit and working
Figure 2 illustrates the schematic diagram of a 2-channel wireless audio amplifier. This circuit is constructed around the 2-channel audio amplifier IC TA8210AH (IC2), the VTF-108 Bluetooth module, two loudspeakers designated as LS1 and LS2, a series of resistors (R1 through R7), capacitors (C1 through C11), and several other essential components. Notably, the VTF-108 module operates on a 5V DC power supply, while the audio amplifier IC2 requires a 12V DC power supply.
The whole design requires the connections as described below.
Connect Bluetooth module to amplifier
The Bluetooth module features four output pins: Lout, Rout, Vcc, and GND. The right channel (Rout) and left channel (Lout) are linked to pins 2 and 7 of IC2, respectively, followed by presets VR1 and VR2, along with capacitors C3 and C5. Pins 3 and 6 of IC2 are connected to feedback capacitors C4 and C6, which are subsequently grounded. The Bluetooth module is powered by a 5V DC supply.
Connect amplifier to speakers
The loudspeaker LS2 is directly linked to the output pins 11 and 12 of amplifier IC2, while a parallel setup is established with output pins 15 and 16 of IC2 to connect another loudspeaker, LS1. To prevent audio signal oscillation, a capacitor is connected in series with a resistor for each wire.
Connect power supply to the circuit
Pins 5, 13 and 14 of IC2 are grounded, while pin 8 is connected to ground through C7, which acts as a ripple-reduction element. Pins 1 and 4 of IC2 are connected to a power supply of 5V. Capacitor C1 is connected to 12V supply line for filtering. Pins 9, 10 and 17 of IC2 are connected to a regulated 12V DC power supply.
Construction and testing
An actual-size PCB layout for the 2-channel audio amplifier is shown in Fig. 5 and its components layout in Fig. 6.
Download PCB and component layout PDFs: click here
Connecting mobile phone with Bluetooth
The first step is to connect Bluetooth of the mobile phone to Bluetooth module (VTF-108) of the audio amplifier. For this, power on the circuit and turn on Bluetooth from Settings of your mobilephone and pair it with VTF-108.
Pagaria is the name of the Bluetooth device (used for testing purposes) that will appear in your mobile phone. Select it, and it will connect automatically. No password is required for pairing. After pairing, you can start sending audio signals to VTF-108.
Sending audio signals to amplifier
Once audio signals are received by VTF-108, these will be transferred to IC2 through its output pins, Lout and Rout. Adjust VR1 and VR2 until you get maximum and noise-free sound from the speakers.
Amplified signal in the speakers
Amplified audio signal from IC2 is transmitted to speakers LS1 and LS2.
VTF-108 module has a USB port and usually comes with a remote. You can use this remote to change the song or adjust the volume. You can also interface a USB device with this Bluetooth module to play songs.