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Audio Amplifier Application Schematic
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Topic: Audio Amplifier Application Schematic (Read 1164 times)
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eerocketman
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Audio Amplifier Application Schematic
«
on:
April 15, 2019, 01:23:38 am »
Hi Everyone,
I am making a bluetooth speaker using the the LM2976 (
http://www.ti.com/lit/ds/symlink/lm2876.pdf
). the typical aplication schematic is pretty straight forward except for a BJT connected to the power leads of the IC. Could someone explain what the purpose of the BJT is? I have highlighted the component in question on the attached image.
Thanks!!
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Circlotron
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Re: Audio Amplifier Application Schematic
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Reply #1 on:
April 15, 2019, 01:27:35 am »
With split pos and neg supply rails pin 7 is normally grounded i.e. halfway between pos and neg. With a single supply rail setup like in this diagram the BJT supplies pin 7 with approx half rail voltage.
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eerocketman
eerocketman
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Re: Audio Amplifier Application Schematic
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Reply #2 on:
April 15, 2019, 01:32:30 am »
Got it, thank you!
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coromonadalix
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Re: Audio Amplifier Application Schematic
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Reply #3 on:
April 15, 2019, 01:32:53 am »
the 2n3904 is not an bjt, its an npn transistor
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eerocketman
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Re: Audio Amplifier Application Schematic
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Reply #4 on:
April 15, 2019, 01:35:30 am »
Could you elaborate on the difference? I thought NPN transistors were BJTs.
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coromonadalix
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Re: Audio Amplifier Application Schematic
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Reply #5 on:
April 15, 2019, 02:46:12 am »
sorry its bipolar junction transistor indeed my bad
mixed with an ujt loll
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Audioguru
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Re: Audio Amplifier Application Schematic
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Reply #6 on:
April 15, 2019, 03:27:26 pm »
What speaker impedance and power supply voltage are you using for the LM2876 amplifier IC?
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Audio Amplifier Application Schematic
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