Introduction: Portable - Mini Amplifier Speaker

About: Master of Information Technology, Universitas Indonesia | SecOps Engineer | A Rhesus(+) | Aries | Photography | Arduino | Computer Geek | Art & Design
In this instructable, I will show you how to make a simple amplifier speaker with common components, it's not just simple but portable. It uses LM386N IC which is a low voltage audio power amplifier. When the project is finished you will have a working simple circuit that can connect with any device as an input, such as Ipod, MP3 player, even your laptop and PC.

This is the video of my portable amplifier speaker
(change the quality for a better view)

The sound quality of this circuit is pretty good.

OK, lets get started!

Step 1: Parts and Tools

Here is all you will need:
- (1) Small drug case
- (1) Perfboard
- (1) IC LM 386
- (1) 8 Pin DIP IC Socket
- (1) 3.5mm stereo jack female
- (2) 3.5mm stereo jack male
- (1) Potensio 5K
- (1) Potensio 1K
- (2) Potensio Knob (optional)
- (1) Resistor 10 Ohm
- (2) Ceramic Capacitor 0,01uF
- (1) Electrolit Capacitor 100uF
- (1) Electrolit Capacitor 220uF
- (1) Speaker 8 Ohm (0,5 - 0,6 watt)
- (1) 9 V battery
- (1) 9 V battery Clip
- (1) On-off Switch
- Shrink tubing
- Jumper wire
- Rainbow wire (optional)
- Male header extended (optional)
- Blackhousing / female 1x1 header (optional)

- Soldering iron
- Solder
- Hot glue
- Mini drill
- Pliers
- Cutter
- Helping hands (if you don't have it, you can build it from my helping hands instructable)

Step 2: Making the Circuit on Breadboard

First, lets put the components on a breadboard so we could see how it worked and how to fit it onto the perfboard. The circuit diagram was made with Fritzing.

The schematic was made with Altium Designer.

Test everything out and make sure that you're circuit is going to work before you start soldering.

Step 3: Move to Perfboard

Step 1
Cut the perfboard about 2 cm x 7 cm.

Step 2
Create paths of the circuit using markers. (this step just for easier our work, and easier for troubleshooting the circuit)

Step 3
Arrange the component, I usually place all components in before starting to solder. But if you want to do soldering one by one,  you can mark on the perfboard which legs of your component will be placed. Like mine, I create a mark on some place to put a header for potensio, audio socket, and header for power source.

Step 4
Check the components once again before soldering.

Step 4: Complete the Circuit on Perfboard

Step 1
- Pin 1 : connect to header male for potensio 5K (see image 3 or 4)
- Pin 2 : connect to one lead of ceramic cap 0,01uF, the other lead goes to positive audio socket.
- Pin 3 : connect to pin 4
- Pin 4 : connect to the ground | connect to negative lead of 100uF | connect to the one lead of ceramic cap 0,01uF and the other lead goes to resistor 10 Ohm. (see the protoboard picture)
- Pin 5 : connect to the other lead of 10 Ohm | connect to positive lead of 220uF
- Pin 6 : connect to 9V (positive) | connect to positive lead of 100uF
- Pin 8 : connect to header male for potensio 5K (see image 4)

Step 2
I'm using male header (extended) for potensio, power source, and for audio socket, so it will easy to modify with other value (specially for the potensio). But it's okay if you want to soldering right to the lead of the component.

# For Potensiometer

* We need 3 header male (extended)
* Put the same size length of the leads for upper and down side.

>> Upper side
- Left : connect to the negative lead of 220uF,
- Center : connect to positive of speaker,
- Right : connect to ground and negative lead of speaker
>> Down side
- Left : connect to the potensio
- Center : connect to the potensio
- Right : connect to the potensio

* We just need 2 header male (extended)
* Put the header upside down

Step 3
Soldering the components carefully.

Step 5: Adding the Potensio


- Soldering the wire to 1st pin, 2nd pin, and 3rd pin.
- Use black housing / header female 1x1 to connecting with the header male on perfboard (later).
- This becomes the Volume Control


- Join the 2nd & 3rd pin of potensio. (cut the wire somewhat longer, in order to unify the two pins). soldering carefully.
- Soldering the wire to 1st pin.
- Use black housing / header female 1x1 to connecting with the header male on perfboard (later).
- This becomes the GAIN

For the wire I usually use a rainbow wire, because it's thin, flexible, and easy to clip with the black housing.

Step 6: Add Stereo Jack Socket

Step 1
- Join B & C pin, solder them together with small jumper wire
- Join A & D pin, solder them together with small jumper wire

Step 2
Soldering a wire between A & D that had been join.

Step 3
Soldering a wire to pin E (this is will be the ground)

Step 7: The Enclosure

Step 1
Drawing the pattern on drug case with marker for placing the switch, stereo jack socket, speaker and potensiometer. It's really helps for drilling.

Step 2
Be careful when you drilling the drug case, because it made of plastic. It easy to melt if the drill get hot, but it's okay you can tidy it up by using a small cutter knife.

Step 3
There will be some scratch and some little cracks on the case, you can covering it with the colour paper or paint it.

Step 8: Put the Circuit Into Enclosure

We will work with a pretty small box, accuracy of arrangement between the circuits is necessary. Don't forget about the space for the battery, because this is portable, so we need internal power source for our circuit.

Step 1
I started with the easy part, it's a stereo jack socket. Drill the case carefully.

Step 2
Measuring the range between stereo jack socket and potensio with precisely, because it will be a problem if they stick too close. And also give the distance between two potensio for sure.

Step 3
Attach the switch and the speaker to the place that we drill before.

Step 4
After we attach the switch to the place, solder the first lead of switch with a wire (include the black housing) (see image 3)

Step 5
Solder the second lead of the switch with a positive wire from battery clip.

Step 9: Putting All Together

I put the battery on the bottom. Then the circuit on the top of it. But you can rearrange between the circuits, for the efficiency. I attach perfboard and the battery with 'Foam Double Sided Tape' instead of using hot glue, just in case I want to modify the circuit later. But if you want to make the circuit steady and permanent I recommend for using some hot glue.

Step 10: Modify As You Want !!

This is small, portable, but also have a limited ability to working. But it is not an obstacle to create something better. This circuit is easy to modified as it's so simple, and there are some ways to modify the instrument :

1. You can replace a battery with an external power source

2. You can change a potensio meter values to get different volume range.

3. You can add LED if you want. The led should turn on when the device is powered and the other function is LED will stop you forgetting to turn off the instrument. But don't forget to add a resistor.

4. You can add a 220 uF variable capacitor instead of simple 220 uF capacitor to change the bass

5. And then let your creativity flow!!

Don't forget to give me a feed back or advice because I'm just a beginner.

Have fun :D

Greetings from Indonesia!!

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