Opinions: On op amp replacement

[Bissell, Harry]

Also, most op-amps have some current limiting for protection. Driving a
capacitive load with a constant (limited) current will definately make
triangle waves, regardless of slew-rate. Harry

> -----Original Message-----
> From:	Brigman, Corley [SMTP:corley.brigman at intel.com]
> Sent:	Thursday, January 28, 1999 7:57 PM
> To:	"icumedia at flash.net" ; "Rene Schmitz" 
> Cc:	"synth-diy at mailhost.bpa.nl" 
> Subject:	RE: Opinions: On op amp replacement
> 
> 
> >They are OK, if you use them with reduced bandwidth, I once used 741 in a
> >poweramp and it was noisy as hell, until I reduced the bandwidth to some
> >7-8 kHz, (I used this amp to drive a 15" speaker)
> 
> i don't know if this directly applies, but I was recently reading about op
> amps,
> and they talked about "large signal" vs. "small signal" operation, with
> some
> 
> definition about where the cutoff point is. basically, the summary was
> that
> an 
> op amp works best with either small signal/large bandwidth or large
> signal/small
> bandwidth, and you can trade one off towards the other. this seems to
> follow. 
> this is due to the slew rate (if the slew rate is 1V/100MS, for instance
> (a 
> fictional and VERY SLOW slew rate, it takes only 50 ms (20HZ) to go
> full-scale 
> for a .5V square wave, but 1000ms (1 second = 1HZ) to go full-scale for a
> 10V 
> square wave. so, at 10V, the 20Hz signal will look like a triangle wave.
> not
> 
> necessarily "noisy", but at least "distorted"....this seems to explain
> somewhat 
> what you are seeing..
> 
> corley brigman
> intel corp.
> corley.brigman at intel.com
> 
> speaking for me, not for intel.