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LM358 as an audio amp
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Mike Warren  
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 More options Nov 4, 9:55 pm
Newsgroups: sci.electronics.design
From: "Mike Warren" <miwa-not-this-...@or-this-csas.net.au>
Date: Wed, 4 Nov 2009 10:25:00 +0000 (UTC)
Subject: LM358 as an audio amp
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The LM358 datasheet doesn't specify EIN or S/N. I assume that's
because it's not very good, but using one would simplify my
circuit greatly as I only have +5V available without a lot
of extra work. I need to buffer an audio signal and add a gain
of 2. The input is about 1VRMS.

THD is not super important, but I wouldn't like to add a lot
of noise.

Has anyone used a LM358 in a similar situation successfully?

--
- Mike


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Phil Allison  
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 More options Nov 4, 11:35 pm
Newsgroups: sci.electronics.design
From: "Phil Allison" <phi...@tpg.com.au>
Date: Wed, 4 Nov 2009 23:05:22 +1100
Local: Wed, Nov 4 2009 11:35 pm
Subject: Re: LM358 as an audio amp
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"Mike Warren"

> The LM358 datasheet doesn't specify EIN or S/N. I assume that's
> because it's not very good, but using one would simplify my
> circuit greatly as I only have +5V available without a lot
> of extra work. I need to buffer an audio signal and add a gain
> of 2. The input is about 1VRMS.

> THD is not super important, but I wouldn't like to add a lot
> of noise.

> Has anyone used a LM358 in a similar situation successfully?

** For non critical applications, within the audio band and with a gain of
only 2  -  there is no problem.

However  -  2 times 1 volt rms is MORE  than 5 volts peak to peak  !!

Beware:  If the output of the LM358 is cap coupled to the next stage,  then
a load resistor to ground is essential to eliminate severe x-over
distortion.

See the Nat Semi 1994 data sheet - page 6.

.....   Phil


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Mike Warren  
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 More options Nov 4, 11:45 pm
Newsgroups: sci.electronics.design
From: "Mike Warren" <miwa-not-this-...@or-this-csas.net.au>
Date: Wed, 4 Nov 2009 12:15:49 +0000 (UTC)
Local: Wed, Nov 4 2009 11:45 pm
Subject: Re: LM358 as an audio amp
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Thanks, Phil. That's enough for me to build a test circuit.

--
- Mike


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TTman  
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 More options Nov 4, 11:59 pm
Newsgroups: sci.electronics.design
From: "TTman" <someone...@ntlworld.com>
Date: Wed, 4 Nov 2009 12:29:58 -0000
Local: Wed, Nov 4 2009 11:59 pm
Subject: Re: LM358 as an audio amp
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"Mike Warren" <miwa-not-this-...@or-this-csas.net.au> wrote in message

news:xn0gh9eln6mnc7000@news.aioe.org...

> The LM358 datasheet doesn't specify EIN or S/N. I assume that's
> because it's not very good, but using one would simplify my
> circuit greatly as I only have +5V available without a lot
> of extra work. I need to buffer an audio signal and add a gain
> of 2. The input is about 1VRMS.

> THD is not super important, but I wouldn't like to add a lot
> of noise.

> Has anyone used a LM358 in a similar situation successfully?

> --
> - Mike

TDA7052/a works....

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Jamie  
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 More options Nov 5, 12:06 pm
Newsgroups: sci.electronics.design
From: Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net>
Date: Wed, 04 Nov 2009 19:36:09 -0500
Local: Thurs, Nov 5 2009 12:06 pm
Subject: Re: LM358 as an audio amp
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Mike Warren wrote:
> The LM358 datasheet doesn't specify EIN or S/N. I assume that's
> because it's not very good, but using one would simplify my
> circuit greatly as I only have +5V available without a lot
> of extra work. I need to buffer an audio signal and add a gain
> of 2. The input is about 1VRMS.

> THD is not super important, but I wouldn't like to add a lot
> of noise.

> Has anyone used a LM358 in a similar situation successfully?

  It looks like it will do what you need.

  Have you thought about using a LMV358 ?
   THat operates at 2.7..5.5 volts.

  THe LPV358 is also lower in current but does
  introduce more noise. Which seems to be a big
  jump compared to the first 2.


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Jamie  
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 More options Nov 5, 12:24 pm
Newsgroups: sci.electronics.design
From: Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net>
Date: Wed, 04 Nov 2009 19:54:21 -0500
Local: Thurs, Nov 5 2009 12:24 pm
Subject: Re: LM358 as an audio amp
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Page 8 in the Oct 2005 edition.

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