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Old 23rd October 2006, 10:10 PM   #1
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Default TDA2050 Oscillating

I'm prototyping a board for the TDA2050, but it has a buzz at the output and if I touch the potentiometer at a certain position I can hear a local radio playing at the speaker.
For now I'm using 100n ceramic paralleled with the 220u caps. When done, I will use polyester ones. The resistor and the cap paralelled with the 22k resistor(feedback) are not present and I don't have the 220p cap in the input to ground.
I'm using the components values suggested in the datasheet and the PCB it's based on the layout presented in the datasheet, too.

There is something wrong with my layout?
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Old 23rd October 2006, 10:11 PM   #2
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Default Schematic

Here is the schematic that I'm using.
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Old 23rd October 2006, 10:14 PM   #3
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The amplifier assembled
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Old 23rd October 2006, 11:12 PM   #4
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Stick a 0.01uf across the input + and -.
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Old 24th October 2006, 04:10 AM   #5
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diegot !!!
It is NORMAL..that BUZZZing sound when u touch the inputs...I don't thing u need to worry abt that....unless u always keep your fingers on the input pins :-)
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Old 24th October 2006, 04:11 AM   #6
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diegot !!!
It is NORMAL..that BUZZZing sound when u touch the inputs...I don't thing u need to worry abt that....unless u always keep your fingers on the input pins
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Old 24th October 2006, 02:08 PM   #7
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sivan_and
it's not about the buzz when touching the input, but it is always present.
I put a 150p cap before the 1k res going to ground, and the oscilations apears to went away. For now I a have a few problems that I believe it's relationed with the power supply, because some falls caused by a shot-circuit, my fault.

I still want to know what you thing about my layout.
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Old 25th October 2006, 05:49 AM   #8
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I didn't find any problem with the layout....Check the resistor values in the gain setting...might've used wrong values..resulting in very high gain and oscillations !!
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Old 25th October 2006, 06:06 AM   #9
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I didn't find any problem with the layout....Check the resistor values in the gain setting...might've used wrong values..resulting in very high gain and oscillations !!
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