I want to write about how I decided to build my own amplifier with Bluetooth connectivity. It all started when I decided I wanted to listen to music directly from my phone and implement this using a separate amplifier instead of connecting to a computer. Yes, I agree, there are many ready-made solutions, but I wanted to make something of my own, even if it doesn’t look perfect. I was less worried about the sound quality. Here is what I ended up with. I must say that the enclosure is not finished yet.
Let me tell you about it briefly. The entire system consists of 4 main modules:
- Class-D Amplifier
- Power Supply
- Analog Audio Level Indicator
- Bluetooth Module for receiving music from a phone
Initially, I thought about making a transistor amplifier, but after reading a couple of articles, I decided to build a Class D one after all. To be honest, I’ve already forgotten which chip it uses. I assembled it from a kit.
I spent some time on the power supply, but in the end, I built it using four 2N3055 transistors, connecting them in parallel with a power margin, hoping to eventually transfer it to a transistor amplifier (based on germanium transistors). Here is the circuit:
I adapted it for my needs accordingly. Thanks to the site:
https://electronicsarea.com/20-amp-variable-power-supply-using-lm317/
I took the transformer from an old, disassembled receiver.
I built the indicator according to this circuit, using the old K157DA1 chip.
I designed the PCB in Proteus and ordered it from JLCPCB.COM
I had ordered the indicators a long time ago for some other purpose, but I ended up using them here.
I decided not to overcomplicate the Bluetooth module and bought a ready-made small module on AliExpress.
The enclosure is made of sheet aluminum.
