“LRAD” Acoustic device

Portable high frequency sound emitter

This was one of those projects that aimed to solve a rather simple problem, but in an overengineered way.

Inspired by the Mosquito anti-loitering device commonly used to prevent loitering outside of stores, I built this compact device to deter loud partying students from gathering outside my window at extremely late hours.

Living just outside CU Boulder campus, this was a much more common and annoying occurrence than you might think.

I quickly cobbled together a prototype using an Arduino Nano and a low wattage speaker. The user could effectively set a frequency ranging from 6khz to up to around 14khz. The device certainly worked quite well at its purpose, but I felt that its form factor was rather disappointing.

The second model I developed used the same electronics but had a sleeker design with some extra functionality. In addition to the frequency range, I added the ability to have a varied wave pattern instead of a constant note. With this model, you could now specify an average tone, and the system would automatically turn it into a fluctuating sine wave.

It also had a better power and toggle switch system, and a cover for the easily damaged speaker. This model was a considerable improvement over the prior design, both in terms of form factor and functionality.

The improved version of the LRAD

Speaker with protective cover

LRAD User interface