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Audio Amplifier

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staticshock:
Well I've figured out the potentiometer. But now I need to add some noise filtering. I've always had trouble understanding where to place capacitors in the circuit. Attached is a drawing of the schematic.

Zero999:

--- Quote from: staticshock on May 24, 2019, 03:34:57 pm ---Well I've figured out the potentiometer. But now I need to add some noise filtering. I've always had trouble understanding where to place capacitors in the circuit. Attached is a drawing of the schematic.

--- End quote ---
It looks sensible, although normally potentiometers aren't used in the feedback loop. The usual way is to use more gain than necessary and attenuate the input with the potentiometers, although it will work.

The only capacitors you really need are on the power supply rails. You can AC couple the signals around the potentiometers, so there's no DC flowing through them, which can cause noise, when they're adjusted.

staticshock:
From my thinking, I set the pots in the feedback because the requirement for the amplifier should output 7V to 11V for the first op-amp and 2.5V to 3.5V for the second op-amp. This was the only thing I could thing of to meet that requirement. Other things that I've been thinking of including or modifying in my circuit is a voltage regulator and an automatic gain control. The voltage source available is 28V and I'll need to step it down to 16-16.5V. I don't think I've been exposed to using voltage regulators except voltage dividers..... so not too sure what I can do. As for the AGC, again not a lot of knowledge either than what its purpose is. Could it be something that I can add into my circuit? For my simulations, it's all been done with PSpice, but I'm not sure if PSpice can simulate noise.

Audioguru:
Why are you amplifying 7V to 10V or 11V? The difference is only a little louder.
Why are you reducing 7V to 3V? The difference is only a little less loud.

I wonder why Radiolistener posted a 70 years old vacuum tubes amplifier?

staticshock:
The input 7Vrms signal is apparently too low and it's just been written down that it needs to be amplified to 10Vrms for intercom. The 3Vrms will be going into three different channels for intercoms as well.

I think he may have posted to troll me  :-//

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