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-   -   I'm looking for help making a small powered speaker (http://www.diyaudio.com/forums/chip-amps/229160-im-looking-help-making-small-powered-speaker.html)

docd 1st February 2013 11:18 PM

I'm looking for help making a small powered speaker
 
I'm looking for some direction/advice.

My poor old computer needs some speakers as the old ones suffered some sort of magic smoke releasing failure and I've got a ton of old scrap electronics kicking around as I really hate to throw away anything with a pcb.

So, I figured this would be a great opportunity for me to get some education about audio equipment and the construction thereof.

I found this ridiculously simple thing on the interwebs 8 Watt Audio Amp

I've got an old atx psu and few crappy misc speakers from the smoldering remains of my old computer speakers and a dead television. I figure I can connect the speakers in a parallel/series circuit to get around 6 watts or so at 8 ohms.

The first question I have is can I substitute the lm383 (which I'd have to buy online) called for in the project with a lm324n I found in an old emergency light?

mickeymoose 2nd February 2013 02:01 AM

No. The LM324 is a low-power quad op-amp, used in low level amplification. The LM383 was designed to drive speaker loads. It is also an obsolete part. I suggest you find a current amplifier IC and follow the manufacturer's design recomendations to avoid disapointment and endless frustration. E

docd 2nd February 2013 02:35 AM

Alright, thanks for the heads up. How about the ECG1232 and TDA2002 that were mentioned in the guide as acceptable substitutes? I couldn't find those on digikey either.

I found a post mentioning a the LM1875 and LM675T, however. They look similar, would one of those work in that circuit?



Concept art of the powered speaker in question:
http://i6.photobucket.com/albums/y206/docd/cod3.jpg

picowallspeaker 2nd February 2013 03:19 AM

Where are the speakers ? In the branches ? :p

why not...hanging from the ceiling !?

stratus46 2nd February 2013 03:34 AM

LM324s are best used as multi-pin thumb tacks. There is not one redeeming quality of those chips, except as thumb tacks. Of course I could be wrong.

G

picowallspeaker 2nd February 2013 03:56 AM

Regardless of which chip is used inside
I'd follow a form for function idea.
The way most Pc speakers are built doesn't fit with usual hi-fi gear.
The volume knob ( with the relative stereo potentiometer) could be
omitted, tough useful for fast and handy action, as it can be controlled with the Pc .
The other thing is that one box is master and the other is slave, so one amplifier would see a 10 cm long wire and the other about 1,5 m .
And , when power rises >10W, the heatsinks associated with the power devices
need to be put to direct air, as also the power transformers need
thermic 'compensation' :confused:
So there's the power cord.
:mad:
That's why separated pieces of equipment guarantee some primary and safe norm for connecting them.

docd 2nd February 2013 03:57 AM

Quote:

Originally Posted by picowallspeaker (Post 3352438)
Where are the speakers ? In the branches ? :p

why not...hanging from the ceiling !?

lol yeah, I'm not much of an artist. They're hiding behind the gray mush I wanted to look like mesh.

Quote:

Originally Posted by stratus46 (Post 3352443)
LM324s are best used as multi-pin thumb tacks. There is not one redeeming quality of those chips, except as thumb tacks. Of course I could be wrong.

G

How about the TDA2030, would it work in the aforementioned circuit?


edit:

Quote:

Originally Posted by picowallspeaker (Post 3352449)
Regardless of which chip is used inside
I'd follow a form for function idea.
The way most Pc speakers are built doesn't fit with usual hi-fi gear.
The volume knob ( with the relative stereo potentiometer) could be
omitted, tough useful for fast and handy action, as it can be controlled with the Pc .
The other thing is that one box is master and the other is slave, so one amplifier would see a 10 cm long wire and the other about 1,5 m .
And , when power rises >10W, the heatsinks associated with the power devices
need to be put to direct air, as also the power transformers need
thermic 'compensation' :confused:
So there's the power cord.
:mad:
That's why separated pieces of equipment guarantee some primary and safe norm for connecting them.

Some of this makes sense to me, I'll stick a little red led where I wanted to put the volume pot to give him an eye. I'm certain I can scrounge a few aluminum heatsinks, some old computer fans, and some thermal grease to cool whatever chip I end up. I planned to house all the speakers in the one fish shaped wooden box (yeah that part is probably not happening lol).

stratus46 2nd February 2013 07:54 AM

Quote:

Originally Posted by docd (Post 3352451)
How about the TDA2030, would it work in the aforementioned circuit?

The TDA2030 will do what you want. I appears pin-pin same as an LM383 and a cousin to the LM1875.

G

sofaspud 2nd February 2013 08:19 AM

My understanding was that the LM383 was virtually identical to the TDA2003. There's a multitude of chipamps that could work for this app. My advice would be to sort out speakers and a power supply from your junkbox and design the stereo around those parts on hand.

sregor 2nd February 2013 11:42 AM

Although tda2030 and lm1875 have same pinout, and are better amps, they won't work with that circuit, The 383 and the tda2003 are designed to have output at half supply voltage with no external components, while the other chips would require external circuitry to do that. Also, IMO the 1875 doesn't work well on just 12v. My 2 cents.


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