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Hi there,
In case you are watching this Electronoobs, I watched one of your videos (from a while ago) on building a bluetooth speaker. (https://www.youtube.com/watch?v=LSFbqxgdpIw)

I am by no means an electronics expert, that's why I'm here asking questions in the first place :p

I built a speaker into a beer crate and it was working fine for a little while, up untill I was about to finish putting it all together. I followed the scematic and I was trying out my new bluetooth speaker with just one genuine Samsung 18650 3.7 battery mounted into a holder that fits 4 and only one speaker hooked up and the thing worked fine. I hooked up the second speaker and put 3 more batteries in the holder, so 4 in total. I tried it again and something went up in smoke, though I am not sure if it's the boost converter or the safe charging module.

One thing that I did notice is that when I measured the voltage at the entry points of the boost converter I got about 3 volts while there is 4v at the batteries. Once again I'm no electronics expert but a 25% voltage loss seems like a lot to me. 

Also the boost converter entry voltage (of 3v) is the same as the exit voltage, so it's not longer getting boosted. So I guess that the boost converter is the component that's gone out?

If that's the case my question is, why did it get fried? I've used exactly the same components as the ones described in the video/description and I'm pretty sure nothing shorted out. The wiring is kind of a mess at the moment but I made sure there's no open wires anywhere.
My only thought was that I caused too high of a current for the boost converter to handle by inserting more batteries.

Used components:



Anyway, here is the scematic I followed (slightly modified) and a few pictures of the project, incase anyone is interested.

Thanks for reading and thanks for any help in advancelaugh

in Circuit basics by (140 points)

1 Answer

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My guess: The speakers need to much power so when you plugged 2, the power that the boost converter could deliver is lower than the power that the amplifier needs, so got burned out. It could be that or maybe a short circuit. Try a powefull boost converter. Sorry for that.

Have a nice day!
by (34.8k points)

Thank you for the very quick response!laugh

Do you have any recommendations for a more powerful boost converter?