Hello. My name is Gennadiy, and i live in Odessa, Ukraine.
Maybe, you have old computer/home audio stereo speakers. Maybe, she don`t working due some reason. Maybe, you want fix it him, like me. And take him new life and new possibilyties. Let`s do it!
Step 1: Old Life...
Just ordinary 2.0 stereo speakers with built-in 2x15 W power amplifier - SVEN AF-11. Wood case, volume, tone and bass regulators, aux in - good speakers from past. I used him with my personal computer, and DVD player for home cinema. But one day she don`t turn on - power failure blow up internal power supply and amplifier.
I have two way - repair old amplifier or try to do something new. I am choose harder, but more interesting way.
Step 2: New Possibilities
First, we need replace amplifier. I choosed 2x15 W amplifier from Aliexpress (link). Miniature, but powerful board, powered by 12V power supply. I used old power supply from non-working notebook with 15V, in this case need to lower the voltage to 12V. For this, i used LM2596S - DC-DC adjustable step-down voltage regulator from Aliexpress (link). Cheap decision with high quality. All working without active cooling, but radiator for amplifier is recomended. So, old characteristics restored.
Add new possibilities. For example, MP3 playback and FM radio. I choosed car MP3 player with remote control from Aliexpress. Attention!There are different versions - 5V and 5/12V! I bought 5V version and burned him with 12V power supply, then I had to buy a new one :)
Remark: i know about another boards with integrated BT receiver and power amplifier, for example: 2-in-1 board from Aliexpress (link), or Hands-free set from Aliexpress (link), but i used this boards for one reason - this modules from other my projects. If you re-used electronic waste - you save the planet from garbage!
Step 3: Extra Possibilities
Something is missing...Something "up-to-date"...For example, bluetooth connection for wireless music playback. Yes, that`s it!
And again, we have two ways: buy a integrated board (BT + amplifier), or just add BT receiver to our system. I choosed second way.
Question: you want cheapest bluetooth upgrade? No problem. See this: stress relief spinner - toy of year. If you have one broken bluetooth spinner like me, then just add him to our sound system. This toy have one audio chanel (mono), so we need connect both inputs on AUX IN on MP3 decoder board.
This toy working with 3.7v Li-Po battery, and charging from standard 5v mobile phone charger, so just cut the battery and connect charger to micro USB port.
Also, you may use another LM2596S module, but this way not cheap.
(Good idea is use 78L05 - voltage regulator on MP3 decoder board, but NO. This regulator is very low-power, just 100 mA, this not enough for working of spinner board.)
Remember: this project just for growing skill of electronics and soldering knowings. Is not serious project and i do him for fun only. There are many ways to repair the speakers, and this is just one of them. Do not be afraid to try and you will succeed. Good luck.