I am a big fan of the audio equipment. Since some time I was looking for some small cheap stereo amplifier, which I could use for the testing of my other projects, to listen music from my phone and etc. The best choice would be a DIY kit - fully complected, easy and fast to assemble. Searching in the internet I have found this.That was exactly what I needed. It was stereo, based on the famous and never dying LM386 chip. Additionally, it has a balancing of the volume for both channels and bass boosting. The best thing - it has an AC/DC converter block included - i did not have to search for suitable power supply block. So. .. I contacted the seller and ordered the kit. It came extremely fast - only for 4 days (Germany ----> Switzerland). Another good thing - the kit does not contain any paper circuit - all devices and their values are printed on the black PCB. In this instructable I will show you the assembling process. Mainly in pictures :-)
Step 1: Soldering the Power Supply
At first I decided to solder the power supply module and to check how it performs. I have soldered the AC/DC module, the fuse holders, the filtering caps, the chock, the power indicator LED and its limiting resistor. I soldered also an AC power cable. This is the right time to declare:
There is a dangerous voltage present on the board - 220V in mine case (110V maybe in yours)I am copy/pasting the safety instructions directly from the source. PLEASE READ THEM CAREFULLY:
"On the PCB exist dangerous for your life high voltages! Be very careful when working with the amplifier! The board shall be placed on insulating surface - Never place it on metal table without plastics or thick cardboard insulation. Never touch the board in the region marked on the picture. It is recommended that the amplifier board is mounted in plastic or wooden case. (I am intending to offer a suitable box 3D printed by me soon on this site). If you want to use a metal housing - mount the board at some distance from the bottom of the box using spacers."
Following the safety instructions I supplied the board placed on a silicon soldering pad. I measured the supply voltage, which was 12V.
Step 2: Soldering the Resitors
Step 3: Soldering the Ceramic Capacitors
Step 4: Soldering the Electrolyte Caps
After them I have soldered the IC sockets - nice feature - if the amplifier chip burns out - very easy to replace.
Step 5: Soldering the Connectors
The input audio jack and the RCA output connectors soldered next.
Step 6: Potentiometers ....
Step 7: LM386 Inserted in the Sockets
Step 8: Knobs..
The kit came with plastic knobs for the controlling potentiometrs, but I had available suitable aluminium ones and I have replaced them.
Step 9: Fully Assembled
I took me 25 min to assemble the whole kit. I tested it with simple middle band speakers. Even with them the sound quality is good. Using the stereo balance potentiometer the volume of both channels can be set according you needs. The bass boosting works also fine. I am happy with this kit - the only thing that I have to do is to find a suitable box for the amp. May be I will print it by 3D printer. I have to find a time to design it in OpenSCAD.