Using consumer-grade power amp as Power opamp

On Monday, May 15, 2017 at 10:49:56 AM UTC-4, 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?
> Any reason they shouldn't be used as power supply regulators, TEC 
> controllers, etc?
> 
> Dave M

As long as you configure it as a inverting opamp with a gain of 20 or more, LM3886 is one big op-amp that works down to DC.  We have them in some mechanical servo systems that need a DC to 2500 Hz response and +/- 12V of drive. . I'm driving 3 ohm and 7 ohm coils with them, no problems.  Must use a split rail, we use +/- 24 volt rails.  

Steve 

On Tuesday, May 16, 2017 at 10:53:27 AM UTC-7, Dave M wrote:
> Don Y wrote:
> > On 5/15/2017 7:49 AM, 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?
> >> Any reason they shouldn't be used as power supply regulators, TEC
> >> controllers, etc?
> >
> > Consider how they handle (highly) reactive loads?
> 
> 
> The reason for my interest in these parts is because I came across a 
> half-full bag of them while helping a friend clean out his recently deceased 
> dad's garage, and while I'm not really interested in building audio stuff 
> anymore, I wondered if they could be useful in other applications.
> 
> Since their main purpose was to drive speakers, which are pretty reactive 
> over the audio range, Zobel networks are commonly used with them.  So I'm 
> sure they don't like to see a lot of reactance. Operating at DC, if they're 
> not asked to handle a lot of AC power, then compensation might not be too 
> difficult. That should be an interesting experiment.
> 
> I might give a shot at using one as a DC power supply regulator, or maybe to 
> drive a power transformer or audio output transformer to make an AC voltage 
> reference.  I've wanted one of those for a long time.  Hmmm... I wonder how 
> they would like being run as BTL amps?
> 
> Thanks for all the suggestions and advice!!
> 
> Dave M


Try selling them on eBay, then tinker with the ones that don't sell?

Michael

On a sunny day (Tue, 16 May 2017 16:03:40 -0700) it happened Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in
<p71nhcpc8djf4im089o8js57gsg4q5ksuc@4ax.com>:


>Try listening to class-D crap via hearing aids that are class-D :-(
>
>Class-D is for audiophools.

Class D means interference.

I have this, nice fan at the back, 19 inch rack:
 http://panteltje.com/pub/301734-an-01-ml-MCCRYPT_ENDSTUF_POWER_PA3000_de-en-fr-nl.pdf
  mixed languages.
Good enough for the living room and street level.
Was only 70 Euro at the time...


It now seems there is a force in the EU, now that UK leaves EU, to move back towards French or German
as the main language.
I remember getting French lessons in kindergarten...
History repeats itself.
What the consequences are for 'the world' I don't know,
and about units, we use a comma where the US uses a dot.
12,5 means 12 1/2
that gets tricky if one needs 12,997 gram.

Will it ever be fixed?

1,999 percent distortion ;-)?
Could be useful in marketing...

On Thursday, May 18, 2017 at 11:58:01 AM UTC-4, srober...@gmail.com wrote:
> On Monday, May 15, 2017 at 10:49:56 AM UTC-4, 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?
> > Any reason they shouldn't be used as power supply regulators, TEC 
> > controllers, etc?
> > 
> > Dave M
> 
> As long as you configure it as a inverting opamp with a gain of 20 or more, LM3886 is one big op-amp that works down to DC.  We have them in some mechanical servo systems that need a DC to 2500 Hz response and +/- 12V of drive. . I'm driving 3 ohm and 7 ohm coils with them, no problems.  Must use a split rail, we use +/- 24 volt rails.  
> 
> Steve

Interesting thanks.  Are those air coils?  How bad is the crossover 
distortion.  I use LM675 for ~10 ohm/1 amp coils.  I tried some 
power opamps (OPA544) and the crossover was worse.  
No (zobel) compensation network.  

George H.