Inspired by some projects i've seen here using LM386..And i got my LM 386 from electronic store the following day.,.But i'm thinking why go with the LM386 so quick,so i decided to upgrade my old powered portable speaker (bought in 2010) first if i can,then proceed to make my DIY Amplifier using LM386..,That's how it all started.
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Step 1: Materials & Tools Needed
1 piece 6" long PVC pipe with 3" inside diameter
2* 3" 1 watt speaker 8 ohm(i used salvaged from an old cd player)
1* 3.5 Headphone Jack
3.5 headphone plug
Jersey Cloth(for speaker grill)
Spray Paint (i used Metallic Black)
Hacksaw (for cutting PVC)
Pencil for marking purposes
Step 2: PVC Cutting & Speaker Preparations
Cut at least 6 inches long of PVC pipe for speaker housing.And prepare the speaker & fit it right first in PVC,& test the speakers.If your two speakers work,it's time to secured the speaker by putting some grills on it.You can use variety of materials to protect the speakers.You can use the metal wire mesh or lady stockings.I used my stocked jersey cloth for the helmets i made in past projects.
Step 3: The Fix
Fixing the problem on non working powered portable speaker always starts in the battery check.As i found my internal battery was corroded that's why it no longer charge itself when i charge it.So i finally decided to removed it eventually.
*Fix & shortening a long cable wire
Solution for long cable wire
Step 4: The Upgrade
Upgrading a powered speaker or any amplified speaker can be sketchy if your not sure of what are you going to do to upgrade it to make it better.It's not just as simple as adding additional speaker would give you a good result or you might end up on a wasted time of effort or stress out your working amplifier that will give you a distorted sound in the end.To make sure with my upgrade I gatherered first some info's how my portable powered speaker was made,and what are it's component..,and search it first if i can upgrade it.
And i found that it has a mono amplifier chip inside (HXJ8002) so i look and dig deeper with the help of google.Until i found out the only thing i can add on it as an upgrade was to add speakers that will comply with the amps specs.(that suits with the supply i have in hand)
Identifying the HXJ8002 with the help of googling:
*This miniature audio amplifier module is ideal for adding output capabilities to your new project.
It is based on the HXJ8002 single channel 3 watts BTL power audio amplifier chip,which features slow harmonic distortion of the audio signal.
*Specifications -on board HXJ8002
-number of channel=Single
-Output power: 3W(for 3ohm load) 2.5W(for 4ohm load) 1.5W(for 8ohm load)
-Working voltage range: 2vdc to 5.5vdc
-Standby Current: 0.6microAmp(typical value) -Board size: 19.8x14.2mm
*Sources HXJ8002 datasheet
*Can be bought online
*Datasheet from AlieExpress
*Speaker impedance calculator
Step 5: Adding Wires
Adding wires is one of the fun part..(soldering the extension wires that i tapped on speakers terminal(Parallel)and attached/soldered the extension wires(with the 3.5 headphone plug) going through the case control panel but failed to add a volume control(adding a potentiometer)the pot i have on hand is 10k so it dont fit with the specs,i tried but with only a few turns..,it's volume goes up or down very fast.So i decided not to include the volume control,maybe i'll add it when i got the correct pot next time.As seen on image is the only control on portable speaker itself.So moved on doing the PVC works for speaker expansion.(as seen on image)
Step 6: Testing
After the wires are soldered properly using parallel connection.Testing was successful.it produces more clear and louder than before(although it only plays in mono)..it Rocks!..so i was happy with the upgrade result.
Step 7: Adding Some Makeups and Results
I finished it by adding some cosmetics by spraying it with metallic black paint.,and adding some brand template from my old speaker grill i kept.(as seen on image).
To add more functionality as an upgrade..i add my spare mini speaker & bluetooth usb module by connecting it all together.And yes it plays and streams my music on iphone wirelessly..And so another satisfying DIY project made that i would add to my collection and use it with my friends and relatives when outdoor needs some rocking sounds.
So that was it., hoping you enjoy reading the whole article and may this project help those who want to upgrade their portable speaker when they need to...
*As i mentioned in intro,my LM386 DIY amplifier will be my next project or just make an upgrade on another powered speaker i have here with TDA 2822 chip amplifier(stereo) and will surely be shared here again next time...
NOTE : I tested it to run on a single 18650 Li-Ion Battery 2200mah capacity it last to play for 5 hrs. playtime