Raspberry Pi Based Wireless FM Microphone

Wireless microphone gives a freedom to move around while amplifying your voice, using a Raspberry pi, a USB microphone, and an FM receiver you can make a wireless mic for your next speech.

This build is from user Khairul Alam Taifur working at the University of Asia Pacific, Dhaka, Bangladesh. A wireless microphone transmits speech into the makeshift lapel microphone over FM radio. The logic behind this is simple, it has a small battery powered radio transmitter in the microphone’s body, which transmits the audio signal from the microphone by radio waves to the nearby receiver unit, and plays the audio.

Wireless microphones are widely used in the entertainment industry, television broadcasting, and speaking to allow public speakers, interviewers, performers, and entertainers move about freely while using a microphone to amplify their voices.

There are many standard frequencies and transmission technologies available for a wireless microphone. They can transmit, in radio waves using UHF or VHF frequencies, FM, AM, or Various digital modulation techniques. Low cost model use Infrared light, Infrared microphones requires a direct line of sight between the microphone and the receiver, while a costlier radio frequency model doesn’t.

To set up the device, we need a Raspberry Pi model – B, USB microphone, FM receiver, Speaker with amplifier, 9V Battery, 5V regulator (LM7805) or power bank, Raspberry Pi case, an SD card with Raspbian on it (minimum 2GB), FM antenna. A microphone converts our voice into electrical signals and the transmitter transmits the signal as radio waves. In this scenario, Pi is acting as an FM transmitter. It’s operating frequency is made to 100MHz.

To test the device, connect a microphone to Raspberry pi, light the pi using the power bank. FM receiver is tuned at 100Mhz and it is attached with the speaker. Everything is set, once you have done with the setup you will be able to amplify your voice with all in one radio or boom box. This is useful in giving lectures or presentations, you could also use it in a van or other large vehicles to communicate over their respective speakers.