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Integrating an LED matrix on the surface of a hearing aid.
Davo Posted: 18 Mar 2024, 02:40 PM

Posts: 1
Joined: 18-March 24
Hi community,

I was inspired by the recent videos uploaded regarding the LED matrix on the earring stud.

I recently received a hearing implant and it's worn externally on my head, held in place by a magnet. It's powered by a 675 ZincAir cell and most importantly, it has swappable covers for customization.

I'd like to go above and beyond and create an LED matrix of similar resolution to the earring matrix and have that as part of a swappable cover.

Is it possible to tap into the power supply of 675 cell and use that power to run a led matrix on the outside of the aesthetic external cover?

What are the voltage requirements for these beautiful compact LED arrays?

You can see the device in question here:

mit Posted: 19 Mar 2024, 07:56 PM
yeah whatever

Posts: 538
Joined: 4-May 16

Zinc air cells do have the highest energy density, but one thing to consider is that they have a limited current capacity, as there's a limit to how quickly oxygen can diffuse into the cell. I am told that it's possible to pull 20mA out of a small zinc air cell, so this possibly isn't so much of a concern, but if you're sharing the power source with the hearing aid you wouldn't want to draw so much that it affects the function of it.

A more important problem is that zinc air cells only provide 1.4V, which isn't enough to light an LED. You can stack two cells in series but the hearing aid likely isn't doing that. Another option is constructing a boost converter, but this adds some bulk to the circuit so it's sometimes easier to just add another battery. The circuit I used for the matrix earring is not particularly optimised - the CH32V003 browns out at 2.8V so it wouldn't even run from two zinc-air cells, but there are other chips that are happy to run down to 1.8V.

While the hearing aid might last for hundreds of hours, showing an LED matrix on it will probably drain it much faster than that. Depends of course on what you want it to display and how often it's turned on.


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