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I Wanted to make one of these for a while now, not because my mp3 player lacked the power to drive my ashamedly poor headphone or that my headphones had a high impedance but because... it looks good and well, maybe in the future i may buy some good headphones and when that day comes. I shall be ready.

I also loved the look of the penguin mints Bought from Thinkgeek, this only aided my decision to make this amp.
So when i decided it was time to stop dreaming and start injuring myself with the soldering iron, i checked instructables first and was amazed to see no one had posted an instructable for this immensely popular diy amp. So i set about making my own, and this is how it went...

Note: for high res images layout images please visit my photobucket, as they are compressed here.
http://s149.photobucket.com/albums/s56/cew27_2007/Cmoy/

Step 1: Tools

The tools you need for this build are nothing special. All you need is:
A soldering iron
Some wire strippers (or in my case a leatherman squirt)
A multimeter

Pictured below my tools. The soldering station is an xytronics lf-2000 that i got about 3 weeks ago. any soldering iron will do, but i got this particular station because it was cheaper than the weller equivalents and parts are readily are available in the UK, and its performance amazes me. Highly recommend xytronics if you are after a good soldering station.

Step 2: The Components

The only thing i had real trouble with getting for this build was the protoboard. Being a radioshack model i found it hard to get in the uk, however after a little digging i found a great website that stocks many radioshack components in the uk at good prices. www.t2retail.co.uk
however if you live in the us, all you need to do is go to your local radioshack and pick up most of the components you need.
Also for uk Builders i highly recommend digikey, they are us based which made me think the delivery would take along time however, i ordered Thursday night and they were here by Saturday morning.

ok so here is the raw list:

220 µF/35 V electrolytic capacitor, radial leads (X2) Radioshack (272-1029) Digikey(P5552)
0.1 µF metallized polyester cap (X2) Radioshack(272-1069) Digikey(E1104)
1/4 W metal film resistor assortment Radioshack(271-0309)
Protoboard Radioshack(276-0150) T2Retail(2760150)
Opa2132PA Digikey(OPA2132PA)
Stereo mini jack (3.5mm) Radioshack(274-0246) Digikey(CP-3513)
DIP-8 IC sockets, gold contacts Digikey(AE7313)
9 v battery clip available from any electrical supplier
volume knob (any will do really) Digikey(226-1033)

and for the volume control you can use either of two options, the alps rk097 pot (with internal switch so when the volume is put at its lowest the switch is off, this means no external toggle switch is needed and makes the overall look neater)
or the Panasonic 10K pot (smoother than alps but without the internal switch)

Volume control, Panasonic 10K, horizontal mount Digikey(P2U4103)
Alps rk097 pot can be bought from http://tangentsoft.net/shop/ or http://www.amb.org/shop/

also optional is an led to tell you when the amp is on, no special led needed just a 3mm.
you will also need an enclosure (altoids tin or penguin mints tin, well any tin really)
i used a penguin mints tin purchased from www.thinkgeek.com

For more information on parts and optional components visit
http://tangentsoft.net/audio/cmoy-tutorial/parts.html#req

Step 3: The Protoboard

To start you will need to understand the board, as you will see from the images below there are two sides. One side played in copper and the other with white markings to show where the copper beneath is.
the components are laid out on the white side and soldered underneath onto the copper pads.
in the diagrams that will come in later steps it is important to note that they are shown on the topside and take not of what side is what (left or right).

Step 4: Adding Jumpers

The jumpers are made from spare resistor legs (or capacitor/led legs) that are then bent and placed into the holes before being soldered on the other side.
the images below show how i did this.
using my leatherman (or similar tool) i cut the resistor legs off of some spare 550 ohm resistors i had laying around. i found that one leg makes two jumpers.
holding the leg in the middle using the pliers i then pushed either side down to prom a 90 degree angle.
putting the jumpers in one at a time saved me the hassle of loads falling out at once as i flipped the board, after the legs are soldered on, clip the excess of with diagonal cutters (i used my leatherman, oh how i live this tool!)
IMPORTANT!!!!! note that the two sides (left and right) are not symmetrical ! always check the jumper (and components later on) are in the correct place before soldering.
once all the jumpers are in place and the excess clipped we can start adding our first components.

Step 5: Adding the Power Supply

The diagram shows the layout and polarity of the capacitors in this section.
i did not put the led in this step as i still need the enclosure for the tin to arrive, however that should be self explanatory, short leg towards negative (black).
i also left the two wires for the battery until last, to prevent the wires getting in the way of soldering.

r1=4.7 KΩ 1/4 W metal film resistor
c1= 220 ΩF/35 V electrolytic capacitor, radial leads

when the components are placed into there holes bend the legs to help hold them in place until soldered, then clip the excess of the legs.

Step 6: Soldering the IC Socket

The purpose of this socket is to allow you to change op-amps without the need to solder, it also prevents the amp from getting hot and damaged during soldering by eliminating the need to solder it on the board
NOTE: the orientation of the ic socket, notch towards the bottom.
the images below show where the legs should sit, however we will not solder the other components till the next step.

Step 7: The Amp Circuit

R2 = 100 K 1/4 W metal film resistor
R3 = 1 KΩ 1/4 W metal film resistor (this gives a huge gain of 11, we will change this later but for now put in the 1k.
R4 = 10 KΩ 1/4 W metal film resistor
C2= 0.1 µF metallized polyester cap (X2) Radioshack(272-1069) Digikey(E1104)

NOTE! in the diagram it show r5 being a resistor, in most cases a resistor isn't needed and another jumper is used, a resistor is only needed if there is distortion ir a hiss when no audio source is connected. so for now solder a jumper in place of r5 as i have.
As you will see i have bent the resistor legs to make it look neither, i suggest you do the same.
Also 2 lengths of wire need to be soldered, the diagram shows these on top however as show in the image below i soldered them beneath also for neatness.

also to note is that the amp is not put in place until last to save it being stressed from the heat of the board as you solder.

I recommend you use a continuity tester (in a multimeter) to test from solder bridges and shorts, remembering where the jumpers are.

however this can be skipped.

Now onto adding the external parts

Step 8: Adding the Jacks and Volume Control

First step is to solder wire to all the pins of the headphone jacks, about 2 inches long. once this is done we can solder up the potentiometer (these are not connected to the amp till later so you dont need to worry about layout, just solder a length of wire to each of the jack pins and for the pot, see the image below)
your jacks layout may differ, however it usually goes from top (closes to the hole) to the bottom
Ground right left .

Note: i means input. so il ir and ig mean Input left input right and input ground, these abbreviations match that of the final layout diagram on the next page

Step 9: Completing the Build

As you will see from the image below, all the connections for the jacks and pot are listed, take a few minutes to understand it all.

the images really do all the talking in this part

Once this is all hooked up correctly, solder your power source (9v battery) and turn it on.
before you plug anything in have a feel around all the components checking for any heat, if it does get hot, take out the battery and check the underside for solder bridges and shorts, also make sure everything matches the diagrams.

Next plug in only your headphones and put the gain up full and listen for any static, if all is good then plug in your mp3 player and take it for a test drive. once again if anything isn't working check the circuit as above

now you may have noticed you cant get much further than half way without suffering from distortion, this is due to the high gain, we will now replace R3 with resistors that will lower the gain now we know the circuit is stable.

2.0 KΩ gain 6
2.5 KΩ gain 5
3.3 KΩ gain 4
4.7 KΩ gain 3
10 KΩ gain 2

I replaced mine with a 2.2kΩstor for a gain of around 6 and this worked well for me.

once you are happy with the gain, you can get to putting it in the tin

Note: The images of the finished amp used in this instructable show another cmoy i have where a Panasonic pot was used and a toggle switch was used in series with the power supply.

Step 10: Enclose It!

I didn't get any images of this as it is pretty straight forward, drill a hole big enough for the part to put through and well, put it through the hole.

REMEMBER: to insulate the bottom of the tin using insulating tape, foam or a cut rubber mat. This will stop shorting.

once its done, enjoy!

If you liked this instructable please comment, rate and show to others.
I also entered this for the thinkgeek competition as not only did i buy the tin from thinkgeek but they also offer a mint tin cmoy, this shows you how to make that famous thinkgeek product.
<p>Thanks a lot Chu. Being an audiophile, I always wanted my headphones sound great. Some of my headphones have high impedence, makes it difficlut to produce good output over mobile phones and MP3 players. I'm gonna try this. Let's see what happens. </p><p>PS: I'm a blogger too http://www.techbii.com</p>
<p>How high of a headphone impedence will this work with?</p>
<p>What rating potentiometer do i use 10K ohms to what?</p>
<p>Hi, I am confused on how to connect the potentiometer and the input jack. Could you elaborate on this part for me and maybe take a look at my build to see where I am going wrong? </p>
<p>hello</p><p>i am looking to make this device as i can get all but one of the parts from maplins...</p><p>the part in question is OPA2132PA, is there an alternative to this ? maybe the LM386 IC ?</p><p>please let me know asap.</p><p>kind regards,</p><p>mike</p>
I would advise going elsewhere to obtain the Op-Amp, maplins - in my experience doesn't offer any op-amps that are overly suitable for this purpose. <br>Have a look for the OPA2134 which has replaced the older 2132 i used in my tutorial. <br>Failing that, i can certainly post out some spares i have laying around here.
<p>oh, that would be wonderful, could i possibly get back to you with that offer if i cannot find any ?</p><p>how much would you be looking to ask ? please PM me :D</p>
<p>oops, didn't see this. <br></p>
I've just built the board for this and I'm ready to solder in the potentiometer but I've gone for a standard stereo pot as opposed to the alps rk097. I'm not sure how to wire the six lugs up to the board, any tips?
<p>Thanks man. Built it and it's running perfectly. just one question though, I'm using the Alps rk097 Pot with a built in switch, is there anyway to wire the LED so that it only lights up when I turn the pot and activate it?</p>
run the led with Rled in parallel with the switching terminals on the pot?
<p>Could you please elaborate :)</p>
<p>I love your perfboard diagrams! Did you use some kind of software or made templates yourself? </p>
<p>Inkscape mate. CTRL+F and type it, already talked about it 4 years ago apparently haha </p>
Thanks man! But I couldn't find anything related to Inkscape (I assume you are talking about free vector drawing app) in this or any other of your instructables :( Perhaps you have a tutorial or willing to share some templates you created? :)<br>Anyway thanks for the idea! I'll try to create my own in Illustrator...
<p>I love your perfboard diagrams! Did you use some kind of software or made templates yourself? </p>
<p>I love your perfboard diagrams! Did you use some kind of software or made templates yourself? </p>
I've built this 2 times already for some reason it doesn't seem to change anything , all my connections are good , but it doesn't change anything volume wise ...
Will any of these work for the amp itself? <br> <br>http://www.radioshack.com/search/index.jsp?kwCatId=13384949&amp;kw=dip%208%20amp&amp;origkw=dip+8+amp&amp;sr=1
Hey sorry it took me so long to respond. We'll, I finished the amp and I try to use it and it's SUPER quiet. I can turn the volume up all the way on my phone and pot and it's still extremely quiet I checked all my connections and they seem fine. I even switched out my op-amp. I don't know what to do
Can you PLEASE make a video of this!! It would be a HUGE help!!!
what are you stuck with buddy? i really should get a video up but i cant remember the last time i built one of these. <br>work and uni detract from hobbies :(
is it ok if i use 100uf 50v capacitors
If i change the input caps to 0.68uf do i need to change the power caps to 680uf? If i were to not use a jumper in R5 what size resistor would i go with? Thanks for helping a newbie out.
would 470uf / 35v capacitors work? please reply!!
Thanks so much for putting this up! I had issues on my amp I tried, and really alittle on the second, I couldn't get any right output. After my first complete failure I decided to order higher quality components but once it was built same thing bad sound in left and no right. I ended up taking the 10k pot out and that seemed to do it. I still have an issue when I move the amp but all I have to do is turn it off then back on and it works. Any ideas why? I checked all my joints and it looked good to me.
Remember to clean off the flux residue after you're done soldering. <br />Acetone nail polish remover will make quick work of it.
can i use the Dual Op Amp from radioshack (276-1715)?
was this answered ? please let me know , thanks!
yes, most dual op amps will work for this.
Did you ever get an answer to this? &nbsp;I would like to build this. &nbsp;Thanks&nbsp;
Hey I have a question. Is it possible to add 4 other ports so that 4 other people could plug their headphones into? Also can you have one of those volume switches to turn on the amp instead of a separate switch and have another switch as like a safety switch? (So that the volume can only go so high so that people don't accidentally bust their eardrums.)
Would using a 220uf 50v cap instead of the 35v increase the output volume and be safe to use? If not what would?
You should be safe to use a cap with a higher volts rating so long as it's the same value. If available, you could get an L/C meter to test the actual value for best accuracy :)
may i use another ic rather than opa2132pa please reply my id is rohitkumarommi@yahoo.com
i noticed on the tangents site that there are way more parts. can i just get the parts from this page and still be fine?
yes all the parts are interchangeable
okay thank you, they are out of stock on the DIP-8 IC sockets, gold contacts Digikey(AE7313) on digikey, does radioshack carry them or do you know anywhere else i can order them from?
any component site will stock them, they are pretty standard.
okay. do you know of anywhere that might sell a kit with all of the required components? i dont want to go around store hopping
Are you based in the uk? If so I can sell you a kit
sorry im in the us
where is the DIP-8 IC sockets, gold contacts? what are they, what do they do, and are they required?
The socket for the op-amp is soldered onto the board as soldering the amp directly would damage it.
Would this work with about 5 outputs for headphones?
Can i get a schematic of the circuit instead of the pictures of the components on the pc board? I'm planning on using a little bread board i have laying around that fits perfectly into an altoids tin.
&nbsp;Maybe there is a simple answer to this. I can only get audio to my headphones through the right channel, my left channel is totally dead. I have no bridges and i've done all i can do to figure it out. Thanks!!
&nbsp;hmmmmm, i had this problem with a unit i had, if there is no bridges (look reaaly close, could just be less than a hair width of solder) then i can only assume a component is faulty, but i never looked to far into what caused mine to behave like that, but it could the the op-amp or any capacitor or resistor that connects to the left channel. sorry i cant help any more<br /> <br />
&nbsp;Thanks, I checked for bridges again, even ran a razor between all the contacts. So I think i'm just going to reorder the parts and have another go at it :D<br /> <br /> Most likely its the op amp, i checked the capacitance of my caps so i'm sure i didn't cook one( which somehow i have done before-really really late night ). So the most expensive part is&nbsp;kaput.... And I even used a socket this time so no magic smoke hahaha.&nbsp;<br />
ive got about 6 spare op-amps i got for free from texas instruments sat here, i never payed for mine. but if you get another and all the parts you need and it turns out to be something other than the op-amp, then you could probably make 2 with all the parts.&nbsp;<br /> good look, let us know how it goes!&nbsp;

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