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Re: Using consumer-grade power amp as Power opamp

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On 16/05/2017 09:59, Phil Allison wrote:
> Dave M wrote:
>
> ----------------
>> Has anyone used any of the consumer-grade audio power amps such as the
>> LM1825, TDA2030, or TDS7297  as a basic DC power opamp?
>>
>
>
> ** Generally they are not unity gain stable.
>
>  Audio power amps have a voltage gain of 10 to 50 times in most cases.
>

Yes, that is a consideration. The "noise gain" needs to be high but not 
necessarily the gain from the input of the circuit as a whole. You can 
of course lower the gain back to unity by attenuating the input, or a 
number of other tricks.

The TDA2030 and similar ones also need a series R-C from the output to 
ground, I think it is called a "Zobel network". Usually the capacitor is 
100nF or so, and the resistor 1 Ohm or so. Without this it can oscillate.

The DC offset voltage is also pretty terrible and unstable with temperature.

The quiescent supply current of the TDA2030 is also quite high and could 
be a problem in some applications.

I have used TDA2030 chips in electroplating power supplies, configured 
as Howland current sources. I also used similar ones in voice coil 
drivers using an old hard driver voice coil as an actuator, and for 
driving power LEDs with a controlled current waveform. The reason why I 
used these audio amplifier chips is because they were very cheap and 
quite powerful.

The TDA2030 is discontinued now. It was one of my favourite parts, not 
because it was easy to use but I guess because I got a lot of use out of 
them (e.g. as a kid I connected one to my crystal radio for driving a 
speaker) and they were very cheap so they seemed like a good deal.

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Using consumer-grade power amp as Power opamp "Dave M" <dgminala@mediacombb.net> - 2017-05-15 09:49 -0500
  Re: Using consumer-grade power amp as Power opamp Don Y <blockedofcourse@foo.invalid> - 2017-05-15 08:09 -0700
    Re: Using consumer-grade power amp as Power opamp "Dave M" <dgminala@mediacombb.net> - 2017-05-16 12:53 -0500
      Re: Using consumer-grade power amp as Power opamp tabbypurr@gmail.com - 2017-05-17 03:04 -0700
      Re: Using consumer-grade power amp as Power opamp mrdarrett@gmail.com - 2017-05-18 09:02 -0700
  Re: Using consumer-grade power amp as Power opamp George Herold <gherold@teachspin.com> - 2017-05-15 08:18 -0700
    Re: Using consumer-grade power amp as Power opamp Phil Allison <pallison49@gmail.com> - 2017-05-15 17:15 -0700
      Re: Using consumer-grade power amp as Power opamp George Herold <gherold@teachspin.com> - 2017-05-16 05:49 -0700
        Re: Using consumer-grade power amp as Power opamp "Dave M" <dgminala@mediacombb.net> - 2017-05-16 13:00 -0500
  Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 15:57 +0000
  Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 09:02 -0700
  Re: Using consumer-grade power amp as Power opamp Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-15 09:03 -0700
    Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:07 +0000
      Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 09:17 -0700
        Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:46 +0000
          Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:08 -0700
            Re: Using consumer-grade power amp as Power opamp Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-15 11:13 -0700
            Re: Using consumer-grade power amp as Power opamp Clifford Heath <clifford.heath@gmail.com> - 2017-05-16 10:14 +1000
              Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:36 +0000
  Re: Using consumer-grade power amp as Power opamp Tim Wescott <seemywebsite@myfooter.really> - 2017-05-15 12:48 -0500
    Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 11:18 -0700
      Re: Using consumer-grade power amp as Power opamp Tim Wescott <tim@seemywebsite.really> - 2017-05-16 10:08 -0500
        Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 11:19 -0700
          Re: Using consumer-grade power amp as Power opamp George Herold <gherold@teachspin.com> - 2017-05-16 11:32 -0700
            Re: Using consumer-grade power amp as Power opamp Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-16 16:02 -0400
              Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:19 -0700
  Re: Using consumer-grade power amp as Power opamp Phil Allison <pallison49@gmail.com> - 2017-05-15 16:59 -0700
    Re: Using consumer-grade power amp as Power opamp Chris Jones <lugnut808@spam.yahoo.com> - 2017-05-16 21:54 +1000
      Re: Using consumer-grade power amp as Power opamp Phil Allison <pallison49@gmail.com> - 2017-05-16 06:06 -0700
      Re: Using consumer-grade power amp as Power opamp tabbypurr@gmail.com - 2017-05-16 06:57 -0700
  Re: Using consumer-grade power amp as Power opamp Winfield Hill <hill@rowland.harvard.edu> - 2017-05-15 18:42 -0700
    Re: Using consumer-grade power amp as Power opamp krw@notreal.com - 2017-05-15 21:55 -0400
      Re: Using consumer-grade power amp as Power opamp Winfield Hill <hill@rowland.harvard.edu> - 2017-05-16 05:53 -0700
        Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 14:23 +0000
        Re: Using consumer-grade power amp as Power opamp krw@notreal.com - 2017-05-16 12:28 -0400
    Re: Using consumer-grade power amp as Power opamp "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:27 +0100
      Re: Using consumer-grade power amp as Power opamp Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 16:03 -0700
        Re: Using consumer-grade power amp as Power opamp "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-17 19:34 +0100
          Re: Using consumer-grade power amp as Power opamp Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-17 11:47 -0700
          Re: Using consumer-grade power amp as Power opamp Phil Allison <pallison49@gmail.com> - 2017-05-18 04:43 -0700
        Re: Using consumer-grade power amp as Power opamp Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-18 16:30 +0000
      Re: Using consumer-grade power amp as Power opamp John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:07 -0700
  Re: Using consumer-grade power amp as Power opamp jurb6006@gmail.com - 2017-05-16 00:45 -0700
  Re: Using consumer-grade power amp as Power opamp sroberts6328@gmail.com - 2017-05-18 08:57 -0700
    Re: Using consumer-grade power amp as Power opamp George Herold <gherold@teachspin.com> - 2017-05-19 06:29 -0700

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