KCX_BT_EMITTER V1.7 Bluetooth 4.1 audio transmitter, USB sound card and analogue input

Product detailed description

KCX_BT_EMITTER is a Bluetooth audio transmitter – the opposite of common audio modules. While a receiver plays sound from a phone to a speaker, this module takes audio from a computer, television, player, or your own project and sends it wirelessly to Bluetooth headphones or a speaker. You can provide audio either via USB, where it identifies itself as a USB sound card in the computer and requires no drivers, or analog via the IN_L and IN_R inputs. After the first pairing, the module remembers the counterpart and connects to it automatically when powered on again. Advanced users can control it using AT commands over a serial line and connect to a specific MAC address or device name.

How it differs from cheap cable testers:

• Transmits, not receives: adds Bluetooth to devices that lack it – older computers, televisions, turntables, or gaming consoles.
• Two input methods: as a driverless USB sound card, or classically via an analog line output.
• Automatic connection: it connects automatically to the last used headphones upon power-up; no operation is required.
• Controllable via AT commands: it can be configured to always connect to one specific device based on its MAC address.

Specifications:

• Model: KCX_BT_EMITTER V1.7
• Type: Bluetooth audio transmitter (TX), operates as a host device
• Bluetooth: version 4.1, stereo transmission
• Power Supply: 3.3–5 V DC (+5V pin or via USB), a 100 µF / 10 V decoupling capacitor is recommended
• Audio inputs:
  • USB: DP and DM pins – the module appears in the computer as a USB Audio device, no driver installation required
  • Analog (line-in): IN_L, IN_R, and AGND pins – for mobile phones, MP3 players, televisions, or custom circuits
• Pins:
  • 1 – +5V: 3.3–5 V DC power supply
  • 2 – PGND: power ground
  • 3 – LED: status indicator output (LED via 330 Ω resistor to ground)
  • 4 – RX: UART serial input for AT commands
  • 5 – TX: UART serial output
  • 6 – IN_L: analogue input, left channel
  • 7 – IN_R: analogue input, right channel
  • 8 – AGND: analogue input ground
  • 9 – DP: USB D+ data line
  • 10 – DM: USB D− data line
  • 11 – CON: input for external pairing button
• Control: PAIR button on the board or an external button on the CON pin, or alternatively via AT commands over a serial line
• Range: 10 m or more in direct line of sight
• Dimensions: 24 × 16 mm

Ideal for:

• wireless headphones for an older computer, TV or projector without Bluetooth
• streaming audio from a turntable, radio or gaming console to a Bluetooth speaker
• custom projects that need to send audio wirelessly (ESP32, Arduino, players)
• adding Bluetooth to a device that only has a headphone output

How to use:

• As a USB sound card: connect the module to a computer via USB cable (D+ to DP, D− to DM, power to +5V and PGND). The system will automatically install the "USB Audio" device, which you can then set as the default output in Windows.
• As an analogue transmitter: feed the audio to the IN_L and IN_R pins relative to AGND, and 3.3–5 V power to the +5V and PGND pins.
• Pairing: turn on the receiving device, then power up the module – it will automatically find and connect to its counterpart. Subsequent power-ups will connect automatically to the last used device.
• Changing devices: turn off the original headphones, turn on new ones and briefly press the PAIR button. The module will forget the previous pairing and find a new device – the search takes approximately 10 to 50 seconds.

Related products:

• Opposite direction – receiving audio via Bluetooth:
  • Bluetooth 4.1 audio receiver XY-BT-MINI
  • BT5.0-Audio PRO Bluetooth 5.0 Stereo Audio Receiver
  • Bluetooth Stereo Audio Modul KN320
• For building your own speaker:
  • Bluetooth Audio Module DW-CT14 2x3W amplifier
  • 2x3W digital audio amplifier PAM8403

Package contents:

• 1× KCX_BT_EMITTER V1.7 module

Note:

• The module connects to headphones, speakers and most Bluetooth receivers that do not require a pairing code. It cannot connect to car radios and devices that require a PIN.
• This is a transmitter, not a receiver. You cannot use it to transmit audio from a phone to a speaker.
• The labels on the board for some pins differ from the manufacturer's documentation: LINK corresponds to the LED pin, AUDIO_L and AUDIO_R to the IN_L and IN_R inputs, and CONNECT to the CON pin.
• This product is not a standalone functional unit and may require professional installation.
• Product images are for illustrative purposes only and may sometimes differ from the actual appearance of the item. However, this does not change their basic properties.