Audio Project 16 10W Mini Audio Amplifier

[hotwaterwizard2]

Where is the Schematic?
How can you get 10 watts from a 9v Battery?

 

[audioguru2]

Hi John,
The schematic is probably the same as the one in the datasheet for its TDA2003:
http://home.eunet.cz/rysanek/pdf/tda2003.pdf

The author of our project had wishful thinking when he stated 10W. He should have said that the circuit is capable of providing 10W, when it has a 14.4V supply and a 2 ohm load.

With a 9V power supply, the datasheet's figure 3 shows it providing only 4.4W into a 1.6 ohm load, at 10% distortion. Of course, its power output is much less with a standard 4 ohm or 8 ohm load.

If you bridge two ICs, using a 9V power supply you might get 10W into a 1 ohm load.

 

[ante1]

Hi Audioguru,

Do you think a 9-Volts battery will supply enough current for this? ;D

 

[audioguru2]

Hi Ante,
Sure a 9V battery will supply a bridged 10W amp. Especially if it is made with 6 alkaline D cells. I used my bridged amp for years at the beach, and it was powered by only 6 Ni-Cad AA cells (5W into 4 ohms, the bridged amps had bootstrapping).

Even a small rectangular "transistor" 9V alkaline battery will power it for a while, if you add a big cap across the battery.

When you listen to music or speech, the average power will be only about 1W, with occasional peaks reaching 10W which is supplied by the big cap.

 

[ante1]

Audioguru,

Well, 6 D cells will not fit in the box shown at the picture. It would have been a nice compact unit as discribed. How much current will it need when testing it with 50mV at 1kHz square wave input? What size of capacitor would I need with a PP3 to hang in there?

 

[audioguru2]

Hi Ante,
Never mind feeding a signal into this little amp. To avoid crossover distortion, each TDA2003 idles with up to 50mA. It ain't no low-power LM358!
Also, the author of ths project and I completely forgot that the minimum voltage rating of the TDA2003 is 8V.
So a brand new PP3 alkaline battery will power a bridged amp for only about 1/2 hour, with no output!

If you want 10W, get out those six D cells, but even they will drop to 8V in almost no time. Using 10 alkaline D cells in series, a single TDA2003 like in our project can give 10W into 2 ohms, gradually dropping in output power for a reasonable length of time.

The author of this project certainly had wishful thinking.

 

[ante1]

Thanks for the info Audioguru, I suspected something like what you just confirmed. 8)

 

[audioguru2]

Mixos,
Could you please add a link to this discussion in the project's text.