i have question and hope you guys can help me.
reently i took apart a couple of wall mounted intercom devices. in these devices i found a speaker and an amplifier. so i thought maybe i can use these parts to make a small portable speaker.
The speakers i found both work. but i have no idea how to wire the amp in there and the best way to supply the power.
the amp model is a TDA1519B. i found the datasheet for it here: http://www.nxp.com/documents/data_sheet/TDA1519_CNV.pdf
my knoweledge of this stuff isn't that high so i can't really figure it out on my own. i was looking at page 8 because it contains a diagram of how to wire it and for so far i think i figured out some of the connections.
PIN 4 and 6 will connect to the + side of the 2 speakers - but where does the - go? is that wired to the - of the battery or to the ground (and how would i achieve this)
PIN 1 and 9 are non inverting inputs. so i assume if i want stereo sound i put the left and right input on these 2 pins. (do i connect the - of the speakers to the - side of a 3.5 mm stereo cable?)
PIN 7 is the supply voltage so this is the place where the power goes in. the document says this should be around 14.4 V with 40 mA. but except for pin 4 and 5 there is no output so again what do i do what the - side.
so this is kinda what i figured out from it but this isn't my field. i know how to solder stuff but i don't really know all this stuff so maybe someone can make a simple drawing of the full schematic?
if someone would that would make me very happy.
When you ask that kind of questions, I'm pretty skeptical that advice given here will be enough.
Anyway, the symbols on the other ends of the speakers mark ground. There are other grounded things as well and you connect them all together and to your power supply's negative wire. You also connect the ground of your input jack to the same point, as well as the IC's pins 2 and 5. Use short wires and connect the input jack's ground to IC's pin 2 with a separate wire.
40mA is the current consumption when the amp is quiet.
>Use short wires and connect the input jack's ground to IC's pin 2 with a separate wire.
To expand on what this anon said, this is done to prevent unwanted distortion from being generated as the speaker current causes a small voltage drop in the wires.
This guy has a very good video on the subject of layout for audio amplifiers, its for the LM386 but the principles are the same for pretty much any chip.
Skip to 5:50 for the subject of layout.
Thanks alot for the quick replies.
I think being skeptical is very smart in this situation :p
but i think i get it now. to the 2nd and 3rd anon you say that wire to PIN 2 needs to be separate from the other wires. So it needs to go from the input jack's ground the the pin and than to minus side from the battery.
so you will have 2 wires going from the input jack 1 to PIN 2 and the other PIN 5 ?
Pin 2 and 5 still need to be connected together but pin 2 should only have the jack and link to pin 5 running from it. Pin 2 is very sensitive and having anything other than the input audio signal in the current path will cause distortions of the sound.
Think about the physical current paths and where the current is trying to flow to.
Basically how >>936881 has drawn it shows how it should physically be wired.
The wire circled in blue should be a direct connection with nothing else sharing the current path, the link from pin 2 and 5 should go directly from pin to pin.
The return current for the audio jack wants to flow out of pin 2, into the jack return wire and back into the device playing music (such as a phone).
The current from the speaker - terminals and pin 6 all want to flow back to the negative of the main power supply. If its forced down the same current path/wire as the jack audio return its going to "fight" and make the sound really bad.
Here, imagine these are real world wires linking everything together.
See how the audio input signal would be forced to share a current path with the other return current, that's what you want to avoid.