Uploaded June 2025 | Updated September 2026, 2 weeks ago
Build Your Own Bluetooth Audio Transmitter with the HW-407 Module (DIY Guide)
Whether you want to stream music /watching Android TV from an older, non-Bluetooth device to your wireless headphones or speakers, or simply add Bluetooth capabilities to a project, building your own Bluetooth transmitter is a rewarding and practical DIY endeavor. This guide will walk you through creating a simple and effective Bluetooth audio transmitter using the readily available HW-407 module.
Why Build Your Own?
Cost-Effective, HW-407 is cheaper
Customization, big battery or power bank, more portable
Connection HW-407 Module
The HW-407, often marketed as a "Bluetooth Audio Receiver Module" or "Bluetooth MP3 Decoder Board," is a versatile and compact module commonly used in DIY audio projects. While primarily designed for receiving Bluetooth audio, it can be configured in a way that allows it to function effectively as a transmitter when paired with an audio input source.
Bluetooth Connectivity: Enables wireless audio streaming.
Audio Output: Usually 3.5mm jack or solder pads for connecting to amplifiers or headphones.
USB Power: Conveniently powered via a micro USB port, or battery.
Compact Size: Easy to integrate into various enclosures.
Important Note: The HW-407 is fundamentally a Bluetooth receiver. To make it transmit, you essentially feed an audio signal into its output, and it will pair with a Bluetooth receiving device (like headphones or a speaker).
Make Bluetooth Receiver
HW-407 Bluetooth Audio Module: The heart of your transmitter.
Audio Input Cable: A 3.5mm stereo audio cable (male-to-male) to connect your audio source to the module. You might need to cut one end to expose wires for soldering.
Micro USB Cable: For powering the module.
USB Power Source: A 5V USB wall adapter, power bank, battery
Soldering Iron and Solder
Wire Strippers/Cutters: For preparing wires.
Project Enclosure (Optional): A small plastic or metal box to house your project for protection and aesthetics.
Multimeter (Optional): Useful for checking continuity and voltage.
Wiring Diagram and Assembly Steps:
The core idea is to connect the audio output of your source device to the "output" terminals of the HW-407 module.
Simplified Connection Overview:
HW-407 Power: Connect a Micro USB cable to the module's power input and plug it into a 5V USB power source.
Audio Input to HW-407: Connect the audio output from your source (e.g., an MP3 player, TV, old stereo) to the audio output pins/jack of the HW-407. This is where the "trick" lies.
Detailed Steps:
Prepare the HW-407 Module:
+5V / VCC: Positive power input.
GND: Ground.
L / LOUT: Left audio output.
R / ROUT: Right audio output.
AGND: Audio ground.
Crucially, for this application, the L, R, and AGND pins will act as your audio input terminals.
Prepare the Audio Input Cable:
Take your 3.5mm stereo audio cable. Cut one end and carefully strip back the outer insulation.
You should find three wires:
One for the Left channel (often white or red, sometimes bare copper with insulation).
One for the Right channel (often red or white, different from the left).
One for the Ground (usually bare copper shielding or a single black wire).
Use your multimeter (if available) to confirm which wire corresponds to which channel and ground by checking continuity on the 3.5mm jack's tip, ring, and sleeve.
Solder Audio Input to HW-407:
Carefully solder the Left channel wire from your audio cable to the L (or LOUT) pin on the HW-407.
Solder the Right channel wire from your audio cable to the R (or ROUT) pin on the HW-407.
Solder the Ground wire from your audio cable to the AGND (or general GND) pin on the HW-407.
Optional but Recommended: Apply heat shrink tubing over your soldered connections for insulation and strain relief.
Power Up the Module:
Connect the micro USB cable to the HW-407 module.
Plug the other end of the USB cable into a 5V USB power source like li-ion battery.
Pair with a Bluetooth Receiver:
Turn on your Bluetooth headphones, speaker, or other receiving device and put it into pairing mode.
The HW-407 module should appear in your receiving device's Bluetooth list (often named something generic like "Bluetooth Audio" or a string of numbers/letters).
Select the HW-407 to pair. Once paired, the LED on the HW-407 should change its state
Test Audio Transmission:
Connect your audio source (e.g., phone, MP3 player) to the 3.5mm jack of your newly wired audio input cable.
Start playing audio on your source device. You should now hear the audio wirelessly through your paired Bluetooth headphones or speaker!
Build Your Own Bluetooth Audio Transmitter with the HW-407 Module (DIY Guide)
Whether you want to stream music /watching Android TV from an older, non-Bluetooth device to your wireless headphones or speakers, or simply add Bluetooth capabilities to a project, building your own Bluetooth transmitter is a rewarding and practical DIY endeavor. This guide will walk you through creating a simple and effective Bluetooth audio transmitter using the readily available HW-407 module.
Why Build Your Own?
Cost-Effective, HW-407 is cheaper
Customization, big battery or power bank, more portable
Connection HW-407 Module
The HW-407, often marketed as a "Bluetooth Audio Receiver Module" or "Bluetooth MP3 Decoder Board," is a versatile and compact module commonly used in DIY audio projects. While primarily designed for receiving Bluetooth audio, it can be configured in a way that allows it to function effectively as a transmitter when paired with an audio input source.
Bluetooth Connectivity: Enables wireless audio streaming.
Audio Output: Usually 3.5mm jack or solder pads for connecting to amplifiers or headphones.
USB Power: Conveniently powered via a micro USB port, or battery.
Compact Size: Easy to integrate into various enclosures.
Important Note: The HW-407 is fundamentally a Bluetooth receiver. To make it transmit, you essentially feed an audio signal into its output, and it will pair with a Bluetooth receiving device (like headphones or a speaker).
Make Bluetooth Receiver
HW-407 Bluetooth Audio Module: The heart of your transmitter.
Audio Input Cable: A 3.5mm stereo audio cable (male-to-male) to connect your audio source to the module. You might need to cut one end to expose wires for soldering.
Micro USB Cable: For powering the module.
USB Power Source: A 5V USB wall adapter, power bank, battery
Soldering Iron and Solder
Wire Strippers/Cutters: For preparing wires.
Project Enclosure (Optional): A small plastic or metal box to house your project for protection and aesthetics.
Multimeter (Optional): Useful for checking continuity and voltage.
Wiring Diagram and Assembly Steps:
The core idea is to connect the audio output of your source device to the "output" terminals of the HW-407 module.
Simplified Connection Overview:
HW-407 Power: Connect a Micro USB cable to the module's power input and plug it into a 5V USB power source.
Audio Input to HW-407: Connect the audio output from your source (e.g., an MP3 player, TV, old stereo) to the audio output pins/jack of the HW-407. This is where the "trick" lies.
Detailed Steps:
Prepare the HW-407 Module:
+5V / VCC: Positive power input.
GND: Ground.
L / LOUT: Left audio output.
R / ROUT: Right audio output.
AGND: Audio ground.
Crucially, for this application, the L, R, and AGND pins will act as your audio input terminals.
Prepare the Audio Input Cable:
Take your 3.5mm stereo audio cable. Cut one end and carefully strip back the outer insulation.
You should find three wires:
One for the Left channel (often white or red, sometimes bare copper with insulation).
One for the Right channel (often red or white, different from the left).
One for the Ground (usually bare copper shielding or a single black wire).
Use your multimeter (if available) to confirm which wire corresponds to which channel and ground by checking continuity on the 3.5mm jack's tip, ring, and sleeve.
Solder Audio Input to HW-407:
Carefully solder the Left channel wire from your audio cable to the L (or LOUT) pin on the HW-407.
Solder the Right channel wire from your audio cable to the R (or ROUT) pin on the HW-407.
Solder the Ground wire from your audio cable to the AGND (or general GND) pin on the HW-407.
Optional but Recommended: Apply heat shrink tubing over your soldered connections for insulation and strain relief.
Power Up the Module:
Connect the micro USB cable to the HW-407 module.
Plug the other end of the USB cable into a 5V USB power source like li-ion battery.
Pair with a Bluetooth Receiver:
Turn on your Bluetooth headphones, speaker, or other receiving device and put it into pairing mode.
The HW-407 module should appear in your receiving device's Bluetooth list (often named something generic like "Bluetooth Audio" or a string of numbers/letters).
Select the HW-407 to pair. Once paired, the LED on the HW-407 should change its state
Test Audio Transmission:
Connect your audio source (e.g., phone, MP3 player) to the 3.5mm jack of your newly wired audio input cable.
Start playing audio on your source device. You should now hear the audio wirelessly through your paired Bluetooth headphones or speaker!
