Making true wireless stereo desktop speakers

Electronics
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Hi fellow makers! I’m 90% done with my project of making true wireless stereo desktop speakers. They sound amazing with good sound stage reproduction! I love that I can take them anywhere and place them just the right distance apart, and from me, to listen to songs with great sound stage effect.

I used Creative Gigaworks T20 speakers because they have separate tweeter and cone speakers. I run them with a small 30w amplifier board (12v power input from a 3S 18650 pack) and the music input comes from a pair of cheap clone AirPod earbuds.

The problem I’m battling with now is I want to use a DC step down module (12v down to 4v) to power the earbuds but after trying 2 different step down modules, the earbuds don’t seem to do well with the power coming from it.

They either keep turning on and off, and if they stay on, there are constant interference sounds audible from the speakers.

If I power them from a LiPo battery then they work just fine and the speakers sound fantastic.

Any advice on how I can power the earbuds from my 12v battery pack so I don’t need to have a separate battery for the earbuds? :thinking:

Thanks!! :slightly_smiling_face:

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My guess is you are getting noise from the stepdown switcher… pretty common.

I would investigate an adjustable linear regulator like:

I don’t know anything about the power specs for the earbuds so I did not attempt the math to see if the LM317 is a good fit, whether it needs a heat sink etc.
You would likely need a RC filter on the input and output.

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The earbuds run on a 1S Li-Ion battery, so I tuned the step down to output 4v and the earbud draws 0.11 amps.