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iPod audio amp

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-Simsy-

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hi, firstly, nice forum :) iv been on it about an hour already :p
ok, so im building a simple stereo audio amp for an ipod inside an ipod - like the ones here:
Speaker made from old iPods - Hacked Gadgets - DIY Tech Blog
The amp i am using is the TDA2822m.
i accidentally pressed enter so the thread was posted incomplete.
continuing on... i have used 2 tantalum caps in place of 2 electrolytic caps both are 100uf. The amp currently does not work, is it because of the caps?
 
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audioguru

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If your capacitors are connected with the correct polarity in the circuit shown in the datasheet of the TDA2822M and using the pcb layout shown in the datasheet and if the battery voltage is 4V to 7V then the amplifier should work fine.

But since you did not post your schematic here then we do not know what you have done.
 

-Simsy-

New Member
thanks audioguru :)
i have used the circuit shown on the data sheet "test circuit (stereo)" http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1464.pdf
im using a test voltage of 6v
and i dont have a pcb as they werent available which made things a bit tricky :eek: (couple of bridges) its probably the polarity. i have the arrows flowing from positive to negative. (conventional flow is used isnt it?)
this is my first actual circuit outside dodgy parallel and series differentiation types at school so go easy :p
 

audioguru

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The amplifiers might oscillate if you do not make them on a compact pcb with a layout like shown in the datasheet.

ST Micro show capacitors with an open line for the positive terminal and a closed line for the negative terminal.
Tantalum capacitors have the positive terminal marked with a "+" sign. Electrolytic capacitors used to be marked the same and are shown with the positive terminal marked with a "+" sign on schematics but newer ones have an arrow pointing to the negative terminal.

I marked the positive terminal on each capacitor for the stereo amplifier.
 

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-Simsy-

New Member
yep, all the caps are correct. my dads multimeter recently broke so i used an LED to see if there's any current but it wouldnt light up when placed upon the power supply pin (2) and the ground pin (4) or between speaker output (either of them) and ground. there was an active input. Does it really need no negative voltage input? thanks :)
 
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audioguru

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If you placed an LED between the power supply pin 2 and the ground pin 1 of the IC then the LED is blown up without any current-limiting resistor in series with it.

The LED would also blow up and maybe the amplifier iC might also blow up if you connected the LED between the output pin 1 or pin 3 and ground without any current-limiting resistor in series with it.

Your dad's multimeter would blow up if you connected it to the power supply like you connected the LED. It short-circuited the power supply.

Or your 6V power supply or battery is dead.

The TDA2822M IC does not need a negative supply voltage. The negative wire of the power supply connects to ground.
 

-Simsy-

New Member
Here is a picture i took of the amp. I traced a couple of branches to make them easier to make sense of. Can you see any flaws?
Thanks
 

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audioguru

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The camera on your cell phone is so bad that I cannot see anything on the photo.
If your speakers are 8 ohms then the very small value of the 100uf output capacitors cuts all bass frequencies below 200Hz.
 

-Simsy-

New Member
i dont actually know the resistance of the speakers as like i said the multimeter is broken and they are unmarked because they're salvaged from an old vaio. How would i prevent the mangling of my tunes? here's a better quality picture.
 

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audioguru

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The photo is much better but I still I cannot see how you wired the perf board.
 

audioguru

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I cannot see what is connected to what.
For such a simple circuit I do not understand why you have wires crossed and all over the place.
 

-Simsy-

New Member
i cant really show you any clearer. I'll show my physics teacher tomorrow and hopefully he'll be able to identify the problem. All the bridges are due to size limitations and the lack of a pcb. I saw a method of making pcb's on the forum so i'll look into that.
Thank you for your help :)
 
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