Clyne Sullivan's Solar-Powered NoiseCard Lets You Know When Things Get Too Cacophonous

Powered by the sun, this business card-sized is designed to measure ambient sound levels — warning when they're reaching unsafe levels.

Gareth Halfacree
23 days agoSensors / HW101

Maker Clyne Sullivan has built a portable gadget that aims to keep you safe when things get loud — by measuring ambient noise and flashing up a warning when it exceeds safe levels.

"Ambient noise levels in populated areas, especially North America, can often exceed what is considered safe for our ears, with prolonged exposure leading to lasting impacts on our health," Sullivan explains. "Through a tool like the NoiseCard, people can become more aware of the noisy environments they're living in (and potentially take action to reduce excess noise exposure)."

The NoiseCard warns when ambient sound levels are getting unsafe — and uses solar energy to do so. (📹: Clyne Sullivan)

Said NoiseCard is a compact business-card sized gadget powered by an STMicroelectronics STM32G031F6 microcontroller, connected to a Knowles SPH0645LM4H-B MEMS microphone. The idea is simple: the microphone records ambient sounds, and the microcontroller lights up on-board LEDs corresponding to the volume — a pocketable VU meter, in essence.

Where things get clever is that you don't need to keep the device charged: a small solar panel to the top-right of the NoiseCard drives all the electronics via a couple of capacitors, with no battery in sight. "It became apparent that the solar cell needs pretty direct sunlight to produce adequate power for the microcontroller," Sullivan admits of this approach's drawback.

Replacing the solar panel with a button cell battery allows the gadget to work underground, too. (📹: Clyne Sullivan)

"This comes down to two reasons," Sullivan continues. "The cell feeds directly to a 1.8V switching regulator, so a voltage greater than 1.8V must be continuously present; second, the large capacitors are still only 660uF total, meaning maybe a couple of seconds of runtime once the sun goes away — if they're fully charged. To remedy [this] I'm looking into better energy storage (in the form of SMD [Surface Mount Device] supercapacitors) and an energy harvesting circuit to get as much power out of the solar cell as possible."

Full details on the project are available on Sullivan's Hackaday.io page, with source code and design files in a Git repository under the reciprocal GNU General Public License 3 and the Strongly Reciprocal variant of the CERN Open Hardware License 2 respectively.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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