Rechargable pocket sized amplifier

In this instructable I gonna try to describe how to make a simple rechargable pocket sized amplifier.
It's works using only two low power transistors and two nickel metal hydride batteries (Ni / MH).
The case is made with 3mm cardboard for making it as light as posible.
Ps: I'm from Argentina so let me know for any grammar mistake

Step 1 Materials

For the case:
A piece of 3mm cardboard
A cutter
Some glue
Screws
Separators

For the circuit:
R1= 4k7 resisor ( yellow violet red)
R2= 1M resistor (brown black green)
Q1= BC548 or 2N3904
Q2=BC327 or 2N3906
C1= 10uF capacitor
2 AAA batteries

Extras:
A batteries charger
A wire for connecting the amplifier to the sound source
A wire for connecting the amplifier to its charger

Comments

[Begradoo]

I built this little amp and it works great considering its simplicity and low voltage. It drives cell phone speakers especially well.
Would it be possible to use a more robust set of transistors and higher uf caps and increase the voltage? Maybe drive a little bigger of a speaker.

[mamajr96]

How exactly do you make the PCB, understand you need to print the PDF, but what exactly do you do.

[dannyo013]

I was wondering if there is a way to make this with a 1/4" input jack for electric guitars. Would make a great portable amp.

[-Syrus-]

How 'bout just adding a 1/4 jack and trying it out?

Dunno about the input impedance...But try it :P

If you are smart you might wanna build something like:
http://runoffgroove.com/littlegem.html

Easy as pie

or

http://www.beavisaudio.com/projects/NoisyCricket/

Better version ! :P Props to Dano the designer.

These are all based upon the allmighty Smokey amp.
Maybe you should just buy one of those ;)

[Daxuto]

Thanks for that, the little gem is pretty much exactly what I needed.

[robot1398]

but they need ic this dosent
so i prefer this one

[-Syrus-]

Then please, tell me what is wrong with using a IC?

OP-Amps circuit mostly use IC's for the bigger gain they can deliver.

LM386 is the most used audio amplifier in DIY and guitar effects.
Its reliable, sounds good and is easy to work with.( As in one chip and two capacitators is the bare minimum for a working guitar amp. eg Smokey amp by Zinky electronics)

So please don't give your opinion.

[Mr_mojo]

Sometimes it's easier to obtain some components such as transistors and capacitors, whereas specific ICs have to be purchased. I for one will be building this as opposed to one of the better ones which use an IC for that very reason, I'm on a very low budget and have these components (or similar once which will suffice) to hand. Just so you know you've brought an extra member to Instructables. I was looking for a schematic for a simple push pull audio amplifier when I found this one, and on reading your comment and finding it so rude I thought I'd sign up and give my reasons for wanting a simple amp as opposed to one that would require me to purchase anything.

[plmqaz1243]

Wonderful world we live in, when people are shunned from giving their opinion by some guy who... I don't even know what you do. Great job.

The misspelled word of the day is:
Mispell

[building_boy]

Not asking, commenting he is sooooo cute!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!

[T-K]

Do I.C. Mr Resistor?

[spystealth1]

That's an interesting way of creating a project box. Usually someone would get some sort of plastic container and paint it, but you use a kind of cardboard wood and instead of paint, you use paper.

[robot1398]

some pics

[Biggimac]

Had to ask!
On your strip board, why did you put your components so far from each other?
They won't bite each other!!

[robot1398]

i know but i had of this size and that time i was not knowing how to cut a strip board

[Mr_mojo]

You use a sharp stanley knife (thats what we call them in the UK but I've seen them called box cutters on here?!) anyway you just score it with the knife then snap it.

[didgitalpunk]

what is the capacitor voltage? i don't think a 35V 10 uF one would do right

[brunoip]

yes, it would work, it is just have a bigger size but it will do fine.

[didgitalpunk]

but will it act exactly the same?

[brunoip]

yes it will

[Tyto Productions]

What kind of speaker did you use? It looks like a computer speaker. Would any speaker work?

[brunoip]

any 8 ohm speaker will work

[lukeD]

great ible *5

Can I hook up 5 big speakers to this amplifier?

[schumi23]

Great ible!
"Ps: I'm from Argentina so let me know for any grammar mistake"
Well, i only found one:
It would be more proper to say "Let me know about any grammar"
Ive been looking for an ible like this all over instructables, and have finally found it thanks to you:) Thanks!

[usbg3rd]

it is not properly biased it clips the portion of the audio signal (negative crust)

[usbg3rd]

hello
can u please tell me what is the output power of the amp ???

[Mr Sinster]

http://www.instructables.com/id/Yet-Another-Pocket-Size-Altoids-Speaker/

hey i was able to make your project!

[wunderdog317]

in step 7 what was that thing not the walkman

[ecopp96]

que tengo que hacer para conectarlo a 12 volts?? Me encanta este proyecto, lo hice pero tiene mucha interferencia y quisiera uasrlo en el auto pero con el encendedor del mismo que tiene 12 volts. Saludos y gracias por el circuito. :)

[brunoip]

En ese aso tenes que reducir la tension, proba conun lm317. Saludos

[ecopp96]

hay alguna manera de reducir la interferencia porque si no hay musica me capta la radio. Gracias por responder tan rapido.

[brunoip]

Usaste cable mallado para conectar el amplificador a la fuente de sonido?

[ecopp96]

no, use cable comun. puede ser eso lo checare. Gracas por el consejo.

[ecopp96]

cambie los cables yy elimine algunas conexiones que habia en el medio del cable de empalmes que hice. Lo conecte con transformador de celular que da entre 4.5 y 9.5 volts y 8000ma y la interferencia se fue que podra ser?

[brunoip]

Los cables si usas un solo tramo de cable mallado para la entrada reducis mucho el ruido. De fuente si usas una de celular de buena calidad y 4.5 volts seguro va a estar bien filtrada y tambien te reduce los ruidos. Saludos

[mgingerich]

Does it matter what kind of transistor as long as you use NPN?

[tobster9103]

one of them is a NPN and the other is a PNP. It does matter. Q1 is NPN and Q2 is the PNP, you can tell from the schematic. Hope this helps out.

[blinkyblinky]

I love it.

[sunnykhaskheli]

Hellow im new and 13 years old, so i dont know much about Q1 and Q2 whats the mean of this

[brunoip]

Q1 and Q2 are transistor, they amplify the signal in order to move the coil of the speaker.
It could be anything, in spanish we name the transistors with a "q"