Instructables
Picture of Simple, Powered Pocket Amplifier
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This is a small powered amplifier that plugs into a 1/8" stereo jack and accepts the same. Many people know nothing about amplifier circuits and would have no idea how to make one, so why don't we let a company make the circuit, and then just tweak it to meet our needs (So admittedly one does need to know a little about electrical circuits, speakers, and soldering).

This is the perfect thing to provide the extra energy needed to power larger speakers with a portable audio device without severely draining battery power. This pocket amp also allows for louder audio through headphones or small speakers. Time to blow out those voice coils!
 
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Step 1: Hunt and gather supplies

Picture of Hunt and gather supplies
For this project you will need:
-A small hearing amplifier, often called a personal amplifier or advertised as spy hearing (I used a
Radioshack brand "amplified listener" )
- Stereo headphone cable with 1/8" jack
-Screwdriver
-Solder
-Soldering iron
-2X AAA batteries (or whatever your particular model requires)
Not shown
-Connecting wire, scrap wire
-Electrical tape
-Hot glue, silicone or epoxy
-Drill and bit slightly larger than the the width of your headphone cable
-Audio source and headphones to check your progress.

Step 2: Void the warranty

Picture of Void the warranty
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Using a screwdriver, unscrew all the necessary screws and pry the case open, remove the battery cover and get rid of any shielding (this does reduce audio quality but we need that space for some wires.)

Step 3: Check the microphones

Picture of Check the microphones
Identify what parts are which and what wires go where. You will need to remove the microphones and use the wires leading to them as your input source

Step 4: Identiy your connections

After severing your left and right microphones, mark which connections go with which microphone: left or right.

Step 5: Wire the connections

Since someone else made the circuit, all we care about are the input and outputs, the output is already wired as a 1/8" headphone jack, and by soldering together the leads to the (now removed) microphones, red to red and black to black, we can then wire the circuit to our own input source

Here some of the wires attached to the board were too short, so I used a piece of scrap wire (yellow) to connect them.
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ross333 years ago
U can get one that splits it into three and dubles the power for 5 more at radio shack
eel laup4 years ago
For the beginners in circuitry, the reason it sounded best was the ground wire from the headphone wire got connected to the ground of the circuit. If it sounded better connected anywhere else I would be surprised.
edfel014 years ago
can u plug in as many speakers u want or can u only have 1 or 2...?
imanalchemist (author)  edfel014 years ago
this amplifier is wired for mono and I have been able to drive two speakers, a public address horn, and a 6.5 in. sub. i honestly have no idea how many speakers it can handle
DIY Dave6 years ago
how much does the amplifier cost?
this amplifier is $24.99
www.radioshack.com/product/index.jsp?productId=2104056
a lm386 alone is like almost 3 bucks but u have to do the rest yourself its like a chip but it amps it up
Just checked on Radio Shack's web site and they have it for $24.99. I'm trying this today.
cyds4 years ago
I've just buyed this radioshack appliance and i've been researching for a while. Wiring like that will make it MONO, The "stereo way" should be: Red cables: don't put them together, one cable is left and one is right channel. Just do your own tests before soldering. In the next step must be: Red with red from the jack cable and Red with White from the jack cable. Black cables: Negative for each channel so these must be put together, In the next step they must be soldered together with the "bare cooper" cable. sorry for my English. it's not my native language
imanalchemist (author)  cyds4 years ago
thanks for pointing that out. i was only wiring it for mono, so i wasn't concerned.
bucko925 years ago
my old earphone cable, which will work well for an input, doesn't have a red and a black cable, but both are unshielded. does it matter which new cable I solder onto which old mic cable? great Instructable btw
imanalchemist (author)  bucko925 years ago
No. I wired mine for mono, so i can't notice a difference
kool! thanks heaps.
stoney1235 years ago
Wouldn't wiring it like this make it mono?
By "microphone," do you mean "speaker?" You tagged them in one of the early images as microphones.
imanalchemist (author)  AdamVigneaux5 years ago
You are correct those are indeed microphones
Oh, I'm sorry. I was unclear on what this device originally did, it would be nice if you could build that into the tutorial; just a line at the beginning that says: "In this Instructable, you'll be turning a device originally used to take in the sounds around you and output them to headphones louder than they came in to a device that can input sound from anything with a headphone jack and output it louder." That's all ramble, right there, but you can trim it down.
agdollison6 years ago
where did you get the siren from
imanalchemist (author)  agdollison6 years ago
It was one of my lucky thrift store finds
more like 'thrift score'
imanalchemist (author)  ethereal haze5 years ago
swish
(removed by author or community request)
imanalchemist (author)  Jonny Mohawk5 years ago
haven't measured or calculated.
Thanks, success with the Maxtreble. I'm interested because I'll be working at a state park for MONTHs far from civilization. Parties happen and music is good. My current speakers barely fill a room and I want to AMP it up without sacrificing battery power, or at least complementing it via trickle charge. So far you seem closest to affordable/practical.
indofulioh5 years ago
Nice headphones. Audio Technica SJ3????? I have those too but with black pads.
imanalchemist (author)  indofulioh5 years ago
Skullcandy Skullcrushers: who needs noise cancelling when you have powered subwoofer headphones
Irony? Who needs midrange and treble anyway?
imanalchemist (author)  baneat5 years ago
these have good highs as well.
The quality of the highs are irrelevant when you can't hear it due to the ridiculously overpowered bass.
imanalchemist (author)  baneat5 years ago
who says that's a bad thing? When I feel I need highs, I'll listen with my other headphones
I prefer accuracy, if the artist intended it to be more bassy, he/she would have recorded it so.
Jimmy16 years ago
I just bought one of these personal listeners from Radio Shack but found that the new model they sell is a sealed plastic case. You can't unscrew or pry it open. Good thing I hung on to the receipt as it's going back to RS.
baneat Jimmy16 years ago
Come on if it was put together there must be some way to take it apart. Use your head! Par exemple I thought you couldn't open up an iPod touch, it's easy when you find the seam.
imanalchemist (author)  baneat6 years ago
Not always true, the clamshell housing could have been sonic welded together making it impossible to take the seam apart without destroying the case.
but this is cheap listening device what are the chances that they did that
You can buy them spy ears at the dollar store for cheaper than ANYTHING in radio shack/the source
yeah, i bought 2 of em at the chinese dollar (and up!) store along w a 10 dollar childs guitar. I drilled a hole at the base of guitar on the side near the bridge to mic the acoustics in the guitar, than run it thru a fender mini stack. sounds horribly awesome w a nice glass slide. later i sub'd the dollar store amp for a 5 dollar voice changer, and now that geetar sounds HOTTT!
i was buying everything for these project and then i saw a pair of Senheisser noise cancelling max headphones for about 35 bucks, so i just leave the amp ad buyed 'em (actually it was a headphone clean out, got 4 different pairs of senheissers, 2 bose and 1 griffin for 300 dollars yeah!) btw do you jailbroke your iPot? i have done it and i luv it
chargeman6 years ago
Great instructable. I just used it for my bike speakers which were underpowered and now they work great. You can fit the shielding back in. I bought the radio shack one and was able to fit it with all the wires and it sounds a bit better.
DIY Dave6 years ago
Are the mics soldered to wires or directly to the board?
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