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Audio amplifier, noob question

Thread starter #1
Hi,
I would create a little audio amplifier (stereo), so I bought a TDA2005.
Now I'm watching ST datasheet, but being a noob, I've some doubts: I'm not sure how wires should be linked from 3,5 jack (male that will be plugged on devices, as pc, smartphone, ...)

So, I'm here to ask you if my ideas are correct or wrong: I attach an image that show my assumptions...
1)
Is right link left and right wires from jack to those 2.2uF capacitors?
2) Is right link groud from jack with all "ground" (that in image I "highlighted" with brown squares), even with negative pole of battery/power source?
3) Datasheet 2200uF capacitor, circled in red in the image, is not linked wrong and may explode? Is right 2200uF capacitor on the top in the figure?
4) Can I try circuit for few seconds/minutes on breadboard (signed max 2A), using 9V or 12V battery?

Thank You Very Much
 

Attachments

MikeMl

Well-Known Member
Most Helpful Member
#2
Hi,
I would create a little audio amplifier (stereo), so I bought a TDA2005.
Now I'm watching ST datasheet, but being a noob, I've some doubts: I'm not sure how wires should be linked from 3,5 jack (male that will be plugged on devices, as pc, smartphone, ...)

So, I'm here to ask you if my ideas are correct or wrong: I attach an image that show my assumptions...
1)
Is right link left and right wires from jack to those 2.2uF capacitors?
Yes. The + end of polarized caps C1 & C2 should be on the right.

2) Is right link groud from jack with all "ground" (that in image I "highlighted" with brown squares), even with negative pole of battery/power source?
Yes, that is the circuit "common" node. Better name than "Ground".

3) Datasheet 2200uF capacitor, circled in red in the image, is not linked wrong and may explode? Is right 2200uF capacitor on the top in the figure?
The + end of C10 & C11 should be on the left end, nearest the IC.
4) Can I try circuit for few seconds/minutes on breadboard (signed max 2A), using 9V or 12V battery?
I suspect that the current draw of this amp will kill a 9V bat very quickly. You might want to look for a regulated 9 to 12Vdc wall-wart. For testing, try the 9V bat. Monitor the battery voltage with your DVM; it will drop below 8V in a short time...
 
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audioguru

Well-Known Member
Most Helpful Member
#3
The capacitance and inductance of all the contact strips and wires all over the place on a solderless breadboard might cause the audio amplifier not to work properly.
C11 on my ST Micro datasheet is correct, I wonder why yours is wrong. A Cheap Copycat manufacturer?
 
Thread starter #5
The capacitance and inductance of all the contact strips and wires all over the place on a solderless breadboard might cause the audio amplifier not to work properly.
C11 on my ST Micro datasheet is correct, I wonder why yours is wrong. A Cheap Copycat manufacturer?
Firstly thank you very much MikeMl

audioguru, thank you, I hope only that short tests (few seconds) on solderless breadboard will not damage amplifier...
I just searched "tda2005 datasheet" on Google, first link bring me to a pdf (Doc ID 1451 Rev 6) on st.com that on page 10 (of 25) shows C11 wrongly placed. It seemed very strange even to me.
 

spec

Well-Known Member
Most Helpful Member
#6
4) Can I try circuit for few seconds/minutes on breadboard (signed max 2A), using 9V or 12V battery?
Corrected thanks to AnalogKid and Audioguru, 2016_11_02

Hi PN,

Have no fear, you can use the TDA2005 amplifier on a 2A rated breadboard for as long as you like; audio amplifiers do not take much current when reproducing music.

Besides, assuming that you have a 12V battery and a 4 Ohm speaker, the peak current would be, 6V/4 Ohms = 1.5A (in fact 6V should read 5V because the TDA2005 output does not swing to the supply rails) and the average current of a sine wave (audio signals comprise sine waves) is 0.707 * peak current. So the average current with a 4 Ohm speaker will only be 0.707 * 1.5A = 1.06A. But the VCC and 0V pins supply the current for both amplifiers on the TDA2005, so in theory the current could be 1.06A * 2 = 2.12A, but the chances of this current being generated with music is slight and the odd peaks of current now and then is not likely to damage the breadboard. You could always link adjacent breadboard pins together to supply the OV and VCC pins if you like.

Also, the 2A breadboard rating will apply to each socket on the bread board not the whole breadboard. But if you passed 2A through all 75, or so, sockets on the breadboard, the breadboard would overheat.

While I fully agree with the other members points about the undesirability of building the TDA2005 amplifier on a breadboard, for the reasons stated, you should be able to get the amplifier working on a breadboard, especially if you use a decent layout, adequate decoupling, and a solid power supply.

The TDA2005 has built-in thermal and current protection and, apart from gross abuse (like connecting the supply lines the wrong way around), you are unlikely to damage the TDA2005.

An old trick when testing power circuits for the first time is to put a current limiting device in the circuit until the circuit is built and tested satisfactorily. In this case, a resistor of around 10 Ohms (3W or more) in series with the speaker would be a good safety precaution. Another safety precaution would be to put a 1 amp fuse in series with the positive supply line (before the supply line decoupling capacitor).

In addition to quickly draining a small 9V battery (PP3), as has been said, PP3 batteries also have a relatively high output resistance (ESR), which increases rapidly as the battery discharges. A relatively small resistance in the supply line can cause the amplifier to be unstable. Also, PP3 batteries are troublesome little things and are really only suitable for light loads. A 1,000uF or greater capacitor across the supply line will help, but you really need a solid supply line.

One of the reasons for needing a good supply line is that, (unlike class A amplifiers, where the supply current drain is constant), class AB amplifiers (like the TDA2005) take relatively large gulps of current from the supply line. Thus, not only will a poor supply tend to cause frequency instability, but it will also generate distortion in the output audio signal.

As to the error on the schematic of the output capacitor being shown the wrong way around: errors are a fact of life. There is a temptation to think that just because information appears in print, especially in books, and on the internet that it is correct. Nothing could be further from the truth, especially on the net. One of the major aspects of engineering is to be able to check for, and handle errors- which is what you have done in this case.:cool: There is nothing more to errors than... er just errors. There are very few areas where, if examined in detail, you won't find errors. You may even find an error in this pist.:D

You can make quite a nice amplifier, easily and cheaply, using a single-chip approach. I have built and repaired quite a few along the way.:)

spec

PS: where are you from? If you put it next to 'Location' on your user page it will display in the box at the left of your posts.

DATASHEET
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000124.pdf
 
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Thread starter #7
While I fully agree with the other members points about the undesirability of building the TDA2005 amplifier on a breadboard, for the reasons stated, you should be able to get the amplifier working on a breadboard, especially if you use good decoupling of the supply line and a decent layout.

In addition to quickly draining a small 9V battery, as has been said, a small 9V battery also has a relatively high output resistance (ESR) which can cause the amplifier to be unstable. A 1,000uF or greater capacitor across the supply line will help but you really need a solid supply line.
Thank you very much spec
I haven't got 1000uF or greater capacitor (I have only 2x 2200uF capacitors already used in this little project), however I believe that I can use 4x 220uF electrolytics capacitors in parallel placed between +Vs (positive pole of capacitors) and ground (negative pole of capacitors)... just for test, after I'll buy a little power supply... about the fact that I should create a "decent layout", well :oops:, I can't ensure nothing :hilarious: (I'm just a noob...)
 

spec

Well-Known Member
Most Helpful Member
#8
Thank you very much spec
I haven't got 1000uF or greater capacitor (I have only 2x 2200uF capacitors already used in this little project), however I believe that I can use 4x 220uF electrolytics capacitors in parallel placed between +Vs (positive pole of capacitors) and ground (negative pole of capacitors)... just for test, after I'll buy a little power supply... about the fact that I should create a "decent layout", well :oops:, I can't ensure nothing :hilarious: (I'm just a noob...)
No problem PN.

Yes, four 220uF capacitors in parallel will be just as good, if not better, than a single 1,00uF capacitor for supply line decoupling.

A good layout generally means short wires. If you post a picture of your layout we can have a look.:)

By the way, the TDA2005 is a pretty well behaved device- they are used in millions of automobile radios. Just make absolutely sure that your supply lines are connected correctly to the TDA2005, and there are no shorts between points on the circuit, before switching on.:)

spec
 
Thread starter #9
Excuse me, I forgot a "little" thing...
I have a set of resistors rated 1/4W, probably those will not burn (I just found an article on a blog that says so), but how can I predict that?

V=R*I
P=V*I=R*I^2=V^2/R

But I don't know V or I in the circuit, because TDA2005 works as a black-box for me...
 

spec

Well-Known Member
Most Helpful Member
#10
Excuse me, I forgot a "little" thing...
I have a set of resistors rated 1/4W, probably those will not burn (I just found an article on a blog that says so), but how can I predict that?

V=R*I
P=V*I=R*I^2=V^2/R

But I don't know V or I in the circuit, because TDA2005 works as a black-box for me...
Only by knowing how the TDA2005 chip works and from the data sheets. But don't worry the 1/4W resistors will be fine.:)

spec
 
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dr pepper

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#11
While I'd agree some of these ic's are tricky with board layout and load impedance, the tda 2005 for me seems robust, I used one to drive scan coils on a monitor tube, and it was badly lashed up on some veroboard and it still worked fine.
If the thing is oscillating and you have no test gear, one crude way to check is monitor the temp of the ic, and the temp of the zobel network (cap and resistor on the o/p).
 

AnalogKid

Well-Known Member
#12
Besides, assuming that you have a 12V battery and a 4 Ohm speaker, the peak current would be, 12V/4 Ohms = 3A and the average current of a sine wave (audio signals comprise sine waves) is 0.707 * peak current.
Actually, the peak voltage will be 6 V, not 12, so the peak current is 1.5 A (assuming 0 V output stage Vcc and GND headroom).

Separate from that, according to the data sheet page 9 the output transistors Vcesat (saturation voltage) is 2.0 V max. each, and the peak-to-peak output voltage for a 12 V supply is 8 V. This is 4 V peak audio voltage, not 12.

ak
 

audioguru

Well-Known Member
Most Helpful Member
#13
Actually if you nit pick you will find that with a 12V supply the peak output voltage is less than 6V and is even a little less than 5V.
I was also going to say the peak current is not 3A but Spec got the total battery current correct since the amplifier is class-AB and makes as much heat as its output power.
 

spec

Well-Known Member
Most Helpful Member
#14
Actually, the peak voltage will be 6 V, not 12, so the peak current is 1.5 A (assuming 0 V output stage Vcc and GND headroom).

Separate from that, according to the data sheet page 9 the output transistors Vcesat (saturation voltage) is 2.0 V max. each, and the peak-to-peak output voltage for a 12 V supply is 8 V. This is 4 V peak audio voltage, not 12.

ak
Well done AK. :banghead:

spec

(PS: Post#6 corrected)
 
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spec

Well-Known Member
Most Helpful Member
#15
Actually if you nit pick you will find that with a 12V supply the peak output voltage is less than 6V and is even a little less than 5V.
I was also going to say the peak current is not 3A but Spec got the total battery current correct since the amplifier is class-AB and makes as much heat as its output power.
Thanks AG, another good observation.:cool:

spec
 
Thread starter #16
I've just tried the circuit on breadboard (I'm quite busy these weeks...) and :facepalm:, as you said, the result was not so good!
The output volume was really low (I tested with 9v and 12v batteries), also with "input volume" really high (TDA2005 didn't heat at all... probably voltage/current to it was not sufficient and/or enough stable).
The quality was inaccettable, you can think as that as a recording of a concert with a smartphone...

But I'm happy that something sounded on speakers, means, I hope, that I'm on the right road. After all, you've already warned me that on breadboard results wil not be great. And this is my first real, little, project with electronics...

Now I'll try to find a power supply and in the meantime I'll draw the circuit on fritzing, for example, to understand how displace components on perfboard...
It will be an "ugly circuit", I already know... but I hope that, at least, It'll play well. I'm just learning :joyful:
 

spec

Well-Known Member
Most Helpful Member
#17
I've just tried the circuit on breadboard (I'm quite busy these weeks...) and :facepalm:, as you said, the result was not so good!
The output volume was really low (I tested with 9v and 12v batteries), also with "input volume" really high (TDA2005 didn't heat at all... probably voltage/current to it was not sufficient and/or enough stable).
The quality was inaccettable, you can think as that as a recording of a concert with a smartphone...

But I'm happy that something sounded on speakers, means, I hope, that I'm on the right road. After all, you've already warned me that on breadboard results wil not be great. And this is my first real, little, project with electronics...

Now I'll try to find a power supply and in the meantime I'll draw the circuit on fritzing, for example, to understand how displace components on perfboard...
It will be an "ugly circuit", I already know... but I hope that, at least, It'll play well. I'm just learning :joyful:
Well, at least you have made some progress.

From what you say, apart from a wiring error or faulty component, it sounds like the amplifier is oscillating which is fairly common with high current and voltage gain audi amplifiers.

All the same, I see no reason why you should not get the amplifier working perfectly.

Are both channels of the amplifier performing in the same way?

spec
 

audioguru

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#18
The voltage gain is set with R2 and R3 as 1+ (1200/3.3)= 365 times so a little microphone signal will cause an output of 1W or more in a 4 ohm speaker. Use a multimeter to confirm that R2 is 1200 ohms and R3 is 3.3 ohms.
 

spec

Well-Known Member
Most Helpful Member
#20
Is C12 a low loss capacitor. like ceramic. Try putting more capacitors in parallel with C12, close or on to the pins of the chip.

Connect 1K Ohm or around ther resistors directly to the input pins of the chip so that the 1K resistors are in series with the input signals.

Can you show the circuit that is connected to the input of the amplifier.

What supply are you using. Put a 1,000uF, approximate, capacitor across the supply lines as close as possible to the chip pins.

spec
 

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