Instructables

How do I build an audio amplifier circuit?

Can someone draw out or point me in the direction of an audio amplifier circuit? I wanna build my own portable speaker system with an amplifier built in, but I wanna build the amplifier from scratch with no bells and whistles. I want it to be high wattage (40 or 50 or more.) and able to drive typical 8 ohm speakers. My understanding of the rules of building circuits is limited, but I can read a schematic and understand how they work. Any Help?

aarons1234 years ago
just by a logitech 5.1 surround sound for $50 by afew double adapters (2 jacks) and ther you go, easy way to have a sub and 5 speakers that can rattle windows or you can go sit on the road and hear it perfectly XD
Wesley6665 years ago
I am submitting an Instructable into the Art of Sound Contest that uses no IC's, just four transistors and other easily found components that boosted my mp3 by like 5 times*! My design for some reason only works with mp3's but not I pods. It is also Mono sound not stereo but that is easy to add. *Also my mp3 sucks and I think I toasted it so the 8 ohm 2 watt speaker was just audible if you put your ear right up against it in a quiet room on full volume. The amp made it so you can hear it easily from 20 feet in a quiet room.
A "chip amp" like the LM3886 (aka Gainclone) is a good way to go if you don't need battery operation. Great sound quality, internal fault protection, and dirt cheap. The most expensive part will be the power supply, but maybe a defunct stereo amp or receiver could be gutted for the useful bits (transformer, filter caps). For battery operation, Class-D is ideal. Search eBay for TA2024 and you'll find some neat little amp boards for reasonable prices. They also have a reputation for good sound quality. 15 watts isn't a lot of power, but if you choose high-efficiency speakers, that could make it sound more like 150 watts. Car amps vary... some units are efficient and have very low current drain when not pounding, so you could get away with running from a small battery or power supply as long as you weren't tempted to crank the volume too high.
sourcery5 years ago
Hi,

Here are two suggestions for chips that you can buy to make an amplifier (with application notes for making simple amplifiers)

This one for a 90W amp: http://www.electrokit.se/download/ta2022.pdf

or this one for a 20W amp:
http://www.electrokit.se/download/tda2005.pdf

There are MANY more to choose from...

Check out this software if you want to breadboard a design:
http://www.synthdiy.com/show/?id=2489
There are many ready made designs for amplifiers on the program homepage (which unfortunately seems to be down right now).

Hope this helps, good luck!
/Kristian

nixiebunny5 years ago
Fifty watts is difficult to build easily. I made my own 15 watt per channel Class D amplifier board http://www.cathodecorner.com/bikeboombox/cdamp, but I am an experienced electrical engineer and I have mad surface-mount soldering skilz.

The other folks are right - don't try to build it yourself. There are many factories in China doing that for you. Buy a 12V SLA battery and a car stereo amplifier.
xaenon5 years ago
I suppose this depends on your definition of 'portable'. Do you mean like a boom box? If so, 40 watts per channel is overkill. You'll need fairly large (and heavy) batteries to keep an amp stoked at that level. bear in mind that most boom boxes operate with less than 10 watts per channel. If, on the other hand, you mean something like you'd haul to a party and plug into the wall to use like a mini-DJ setup, there are amplifier kits available out there, capable of outputs ranging from a fraction of a watt on up to 100+. The nice thing about a kit is all the necessary parts and instructions are supplied, as well as a circuit board - ideal for 'limited experience'. Google is your friend.
brendan945 (author)  xaenon5 years ago
The DJ setup is pretty much what Im thinking. I was never planning on batteries in the first place but it was an interesting after thought. The more I think about it though, the less I think its an option. Kits sound like a good idea, but I'll have to look and see how much they're gonna run. Im going for inexpensive above all else. I also wanna intergrate something to serve as a sort of media PC so I can have all my music and possibly music videos on-board, with a touch screen on the front for making selections. Probably take an old laptop and buy a touchscreen overlay.
endolith5 years ago
Agreed that car stereo amplifier chips are the best idea here. They do most of the work for you with relatively few external components. D class chips would give you more efficiency and lower weight, but aren't as easy to build.

Just get a class AB amp chip and copy the evaluation board PCB layout as closely as possible.

http://www.st.com/stonline/products/literature/ds/1478/tda7265.htm
jeff-o5 years ago
Portable AND up to 50 watts? With limited electronics experience? Hmmm, dig up a used car amplifier, a car battery, and some speakers. Shove them in a box. Done. ;)
:-D i have a spare alpine 100watt amp.
That would work. Just make sure the battery or power supply has enough capacity!
brendan945 (author)  jeff-o5 years ago
Good thought. I was hoping to keep the weight relatively light. Though with your idea, I could add a DC power supply that plugs in and pushes the amp. I could then have the option to add batteries later. My initial idea was more along the lines of something that plugs in, a kind of beefed up boom box with my own twists.
Sure thing. In that case, replace the car (or motorcycle) battery with a computer power supply. These are typically cheap or free (if your workplace has an IT department, they probably have a few, otherwise ask on Freecycle), and should provide enough juice at the right voltage (12V at 5 amps).
jinventive5 years ago
You could go to this page which has many good amplifier designs, some way more than 50 watts, or you could look around for a car stereo amplifier chip which are often single supply (can be run from +12V and 0V, instead of the +12V, 0V and -12V that most amplifiers use). The car audio amplifier chips also often have high output power and they could be bridged to give even more power. Try searching on google for the TDA2005 or car radio amplifiers.
Sandisk1duo5 years ago
what i've found is that it is cheaper to buy an amp then to make one
the components cost more then the amp :(
i have searched the interwebz far and wide...

but if you want a crappy amp, the TPA3122D2 is the way to go (15W amp, bridgeable) 20 pin DIP package

(oh and you can get the chip for free : )
randofo5 years ago
I don't know too much about building high wattage systems, but making it portable will be tricky since the more watts you have, the larger the battery you will need. Just how portable do you want it to be?
brendan945 (author)  randofo5 years ago
Oh , I guess I didn't say enough, portable and plug in is fine. doesn't necessarily have to be battery powered, but an AC/DC option might be nice.
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