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Engineer a Spectacular Holiday Display

Grab some lights and a Raspberry Pi, and you’ll be in business

The final result in front of the iHeartMedia Toledo building. Thirty-two boxes of Christmas lights, two solid-state relay boards, two IC inverters and one Raspberry Pi: These components were stacked precariously on my desk early in my internship at iHeartMedia Toledo.

My task, according to Market Director of Engineering and IT Gary Fullhart, was to create a holiday light show that synced to our Christmas music station, WRVF(FM), “101.5 The River.”

After researching and testing, I found the assignment exciting to build.

For this project, the Raspberry Pi runs open source software called LightShow Pi. The program takes audio and breaks it across light channels, similar to a light organ. Utilizing the Raspberry Pi Model 2B, a maximum of eight GPIO pins create the light channels.

Pre-recorded audio files or an audio source brings the light show to life. LightShow Pi reacts to changes in sound; therefore, louder songs or songs with more “action” create a better reaction. Lights rapidly pulse as they impersonate the sounds of an artist’s voice. On the other hand, quiet selections with less action will cause the channels to drop. After a few seconds, the audio returns and the show resumes.

The first version of this project features eight plugs that correspond to a different GPIO pin on the Pi.

The second revision uses 16 plugs and an IC Inverter to create alternating channels. Channels 1 and 9, 2 and 10, 3 and 11 and so on run as opposites. The leads from the Pi connect to a solid-state relay board, which controls the power going to each plug. Inside the unit, a radio is the audio source. An external adapter converts the 1/8-inch output from the radio into USB.

Because the Pi is using audio from a radio, and not from inside the station, it continues to sync correctly, even when using profanity delay or with HD Radio delay. Listeners can tune in with a car radio, and see the light show in real time.

This unit contains a Pi, small radio and two solid-state relay boards.

The second revision features 16 channel outputs. In front of the iHeartMedia Toledo studio building, we constructed a light tree composed of strands of 17-foot LED lights stretched as rays from an existing flag pole.

A multi-colored strand and a green strand wrapped together create an alternating effect. The unit sits mounted on the flagpole and strands extend down from the top.

Multi-colored lights are on Channels 1–8 and the green lights are on Channels 9–16. When the program is inactive, Channels 1–8 are off, activating the green lights.

The program reacts to both changes in audio and the volume of the sound. During commercials or quiet sections of a song, the Pi will turn off all GPIO pins, leaving behind the static green tree.

Programming a python code simplifies the process of changing the patterns on the tree, which also enables testing without an audio source. By using any computer on the network or a mobile phone, anyone can control the patterns and make changes to Lightshow Pi using an SSH client. I used PuTTY to access the Raspberry Pi.


For the iHeartMedia Napoleon station, the first version of the modified device was sufficient because we were only decorating windows in front of the building.

The iHeart Lima station uses the second version. With the help of Engineer Josh McKinley and Producer Rodney Thomas, the front of the building and surrounding bushes represent different audio channels. When active, the inverted channels create an all-white background.

The Raspberry Pi is a powerful tool. And with the help of LightShow Pi, you, too, could create a spectacular holiday display for your own stations.

Learn more about LightShow Pi online at

Send your own tech project stories to us for possible publication at [email protected].

Alec Connolly attends the University of Toledo’s engineering program where he majors in Electrical Engineering. He is in his second term of co-op, which he has spent with iHeartMedia. Connolly also works for Learfield as their away game engineer, where he produces the University of Toledo’s football games.