Build Your Own 50m Stereo Wireless Audio Link Circuit

Complete Project:

Description

This stereo FM wireless microphone also serves as a reliable audio link. Testing extended the range beyond 50 meters and demonstrated excellent performance. This wireless microphone distinguishes itself through its stereo capability, offering surprisingly high-quality sound. Furthermore, it provides a substantial range, exceeding 50 meters, maintaining a clear, noise-free signal. While the initial price might raise concerns about quality, a trial is recommended to discover its surprising capabilities.

Construction is straightforward, demanding minimal setup and offering excellent value. The transmitter module is already integrated, requiring only the assembly of the microphone module, which incorporates electret microphones, a preamp, and level controls, followed by soldering the transmitter module onto it using a “piggy back” style connection.

FM Transmitter:

The transmitter module is crystal-locked, eliminating the drift issues associated with earlier wireless microphones. Moreover, it incorporates a sophisticated synthesis circuit, enabling the selection of seven different frequencies spanning 106.7MHz and 107.7MHz. Adjustable on-board preset pots allow for the fine-tuning of channel sensitivity, accommodating microphone variations or differing level requirements in each channel.

The transmitter module is capable of operating at line level when a line-level transmitter is desired (e.g., for audio distribution within a home environment). Its output sensitivity is approximately 100mV. Oatley Electronics provides the transmitter module independently if preferred. Further details regarding this module will be provided subsequently.

Parts Layout:

A choice of two power supply levels – 3-6V or 7-15V DC – is available. Utilizing the latter option minimizes current consumption. The transmitter module also includes a 5V output rail to power the preamp module.

Two electret microphone inserts are included in the kit. These can be directly soldered to the printed circuit board for a self-contained project or connected via suitable lengths of mini shielded coax cable. Alternatively, standard microphones – electret or dynamic types – can be used, though provision is not made for their direct connection.

Typical Specifications: