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A mini portable speaker for outdoor adventures! This design uses an easy, accessible & powerful standard schematic. Here's a video of it in action.

Material costs are low (~ $20), although it can take a decent amount of time to build!

Step 1: Materials

-- LM386 audio amplifier

-- 3 Capacitors: two 220 microF, one 10 microF

-- 4 Resistors: two 10 Ohm, one 1 kOhm, and one variable 10 kOhm (w/ an SPST or SPDT switch)

-- 9 V battery + battery clip

-- Speaker (4 - 8 Ohm)*

*Have a broken sound system? Harvest the speaker!

-- 1/4" (or 1/8") mono panel-mount audio jack

-- PCB Board

-- 22 Gauge stranded wire ( ~ 1 ft)

-- Case**

**There are many options! My case is a mini-lunchbox type thing found at a thrift store for $1. Look around the house, or peruse a thrift store for vintage tins, cigar boxes or metal piggy banks. Look for containers made from metal, wood, or rigid plastics.

-- Recommended: Piece of wood for speaker mount

This improves audio output by providing a solid resonant surface. This step was somewhat involved (tool heavy), can be accomplished in many different ways, and is entirely optional, so I will just briefly cover this part of the process.

Step 2: Tools

-- Soldering iron, solder + solder sucker.

-- Epoxy or other bonding agent.

-- Wire strippers

-- Highly recommended: Multimeter.

-- For the case, you also need a drill.

-- To mount the speaker in wood: a dremel or other wood cutting tool (+ clamps + eye protection)

Step 3: Build It! Pt. 1

1. Solder wire leads to the audio input.

2. Solder wire leads to the speaker (recommended to use at least 6" leads).

3. Solder wire leads onto the variable resistor (potentiometer) pins.

Check the resistance between the difference potentiometer pins w/ a multimeter before soldering to determine the functionality of each pin.

Aside: Wire color, while entirely optional, helps distinguish the different pin functions. To wire the potentiometer so that the volume increases from the "off" position: Pin 1 goes to ground, pin 2 goes to LM386 pin 3, and pin 3 goes to the positive audio input.

4. Solder wire leads to the switch pins on the bottom of the potentiometer.

Check resistance across switch pins w/ multimeter. This potentiometer switch has a front pin that goes to ground and the left front pin to positive input.

Step 4: Build It! Pt. 2

If schematic makes sense, skip next two steps (still suggested to build on breadboard first).

1. Build circuit on a breadboard. Recommended to draw out how it will transfer to the PCB board pads.

Connect a battery and check audio input w/ either a multimeter or an actual source (will need a 1/4" or 1/8" headphone cable).

2. Solder LM386 amplifier to PCB board.

3. Solder the battery clip leads and potentiometer switch leads to the PCB board.

The potentiometer leads are inserted between the positive battery lead and the 10 ohm resistor going to the LM386 voltage source pin.
Note: If your variable resistor does not have a switch, it is highly recommended to include a power switch for the battery.

Step 5: Build It! Pt. 3.

1. Solder the remaining components to the PCB board using the PCB pads and/or wires (breadboard pictured for clarity).

Here's one of many ways to approach this:

A. Connect LM386 pins 2 and 4 to ground.

B. Connect 1kOhm resistor and 10 microF capacitor from LM386 pin 1 to pin 8 (shorter leg (negative pin) of the capacitor connects to LM386 pin 8).

C. Connect the long leg (positive pin) of the 220 microF capacitor to LM386 pin 5. Connect one side of the 10 ohm resistor to the short leg of the capacitor, and the other side of the resistor to ground. Connect the positive speaker lead to the short leg of the capacitor, and the negative lead to ground.

D. Connect one side of 10 ohm resistor to LM386 pin 6 and other side to positive battery (w/ switch). Connect long leg of 220 microF capacitor to LM386 pin 6 and short leg to ground.

E. Connect the potentiometer pin 1 to ground, pin 2 to LM386 pin 3, and pin 3 to positive audio input.

F. Connect negative audio input to ground.

Step 6: Case It! Pt. 1

1. Plan + mark location of each of the components.

The potentiometer, or volume knob, power switch, audio input, and speaker are installed on the exterior. The PCB board and battery are on the interior.

2. Drill two holes in case exterior for the potentiometer knob and for the audio input.

If case is not metal, recommended to include a sheet of metal to provide a better ground for the audio input.

3. Remove screw heads from potentiometer knob and audio input. Push potentiometer knob and audio input through the holes and reattach screw heads.

4. Check connections w/ a multimeter and/or an actual audio input (will need a 1/4" or 1/8" audio cable).

5. Dab epoxy onto bottom of case to adhere the PCB board.

To secure the 9V battery: use velcro strips, or make a quick fabric pouch and epoxy the pouch to the case.

Step 7: Case It! Pt. 2

1. Mount the speaker in wood or in case exterior.

There are different options depending on your chosen case and available tools. It sounds great w/ wood, otherwise you can also mount it directly to the exterior of the case.


One option is to follow the design featured in this Instructable:

A. Cut a piece of wood to fit inside the case (bottom slab). Cut a hole in the middle large enough to pull the speaker through.

B. Take a thin piece of wood and cut a notch out. The notch should be sized so that the screw holes of the speaker frame sit on top of the wood.

C. Optional: Screw speaker into top wood ring. Screw top ring into bottom slab.

Step 8: Check It + Go Adventuring!

Test the electrical connections by plugging in an audio source (e.g. electric guitar or mp3 player). Check that the potentiometer effectively controls the volume and that the switch turns the system on/off. Once everything is working, coat electrical connections in epoxy.

Take your new portable amplifier to bring music to your next outdoor adventure!

Thank you for your reply
Hi, can i use 12v battery in this circuit??
<p>What's the current output? Check the manufacturer specs of the LM386 and see if it can handle the battery voltage/current. </p>
<p>hey i have </p><p>IC:</p><p> TDA2822M</p><p> TEA2025B</p><p>CAPASITORS:</p><p> 2200uF 16v (1)</p><p> 100uF 16v (7)</p><p> 220uF 10v (2)</p><p> 220uF 25v (2)</p><p> 0.47uF 50v (2)</p><p> 3.3uF 50v (1)</p><p>and 2 potentiometers 10K </p><p>and alot of resistors </p><p>and iam a complete beginner and i want someone to tell me how to make an amp with this components please</p>
<p>Hi there! The best way to get started is to find a tutorial and follow it step by step. This one is a good place to start. Let me know if you have any questions once you get going.</p>
<p>thank you very much for replying but i dont have the 10 microF capasitor</p>
<p>www.ebay.com :)</p>
<p>thanks but is there any way to make a 10w amplifier with 4 channels </p><p>because i found 4 10watt speakers lying around and i didnt find anyone on amazon or ebay</p>
<p>Hmm usually speakers are rated by ohms, so I'm a bit unsure. Try looking for a tutorial that utilizes the components that you have on-hand, or just start playing around with components and see what happens! </p>
<p>This would make a nice amp for a smartphone. One could even build in a slot to hold the phone.</p>
<p>Yea it's perfect to play music from a smartphone or iPod. Great idea to build in a slot for the phone, will have to do that for the next one!</p>
<p>What changes would you suggest to make this stereo compattable? I love the idea behind this. </p>
Thank you! Also, looks like irishjim68 did a good job of answering your question, so I'll leave it at that :)
<p>Add a second 386 amplifier, a stereo panel jack and another speaker. Run left and right inputs from panel jack to individual amplifier circuits and output them to the separate speakers. 2 LM386 based amplifiers can be run from a single 9volt battery, but for longer life, add a second battery in parallel, or just run each amp from it's own battery.</p>
<p>Here are a couple pictures of an LM386 based amp that I made for a phone/MP3 player stereo input. I used two identical circuits, split the left and right inputs to individual circuits and output each to it's own speaker.</p>

About This Instructable

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Bio: Dabbled in dark matter, settled into engineering with a blend of inventing and teaching, always trying to solve problems + learn new things!
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