# Audio amp question

Discussion in 'General Electronics Chat' started by Garurumon, Jun 5, 2013.

Mar 17, 2013
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2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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I vote for 9V.

3. ### Garurumon Thread Starter Member

Mar 17, 2013
99
1
Can it be calculated?

4. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,993
1,116
Sure we can. In datasheet we can find that for Vcc = 11V and RL = 8Ω Po = 7W.
So the voltage across RL is equal to Vo = √P*R 7.5V
So amp has Vast = 11V - 7.5V 3.5V saturation voltage.
You want Po = 3W_max
So
Vo = √3W*8Ω = 4.9V

So

Vcc_max = 4.9V + 3.5V = 8.4V

5. ### Garurumon Thread Starter Member

Mar 17, 2013
99
1
Great, so it'll be even portable with 9V battery, hooray.

Thanks mate

6. ### Shagas Active Member

May 13, 2013
802
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If you are talking about the classic 9volt battery then that will only supply 100mA at most before it's voltage sags to less than 7 volts so you will have to find something which can provide more power . perhaps an 8.4 volt Li-ion or Li-po