Reproducing 741 opamp slew rate

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

Guys,

I'm stumped on this one. How do I emulate (hardware) the slew rate of a 741 opamp with modern opamps (OA) like the TL071? The slew rate should be constant with linear slope and still allow me to adjust the loop gain with a standard resistor feedback network.

I've tried a simple integrator cap from (-) to Output but the OA gets weird - the signal likes to favor the negative rail and I don't know enough about the internals to know how to fix it.

I'd also like to control the OA gain with standard resistor feedback but then the feedback cap just causes phase shit in the output - as expected.

I've tried some combinations of RC networks and zeners in the FB loop, but they never give me what I need.

Any help is appreciated.

analogmonster · Joined: May 30, 2011 Posts: 89 Location: Germany

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

Good point.

Not academic. Since 741s aren't made anymore I'll need them in quantity for a new product design - and obviously don't trust Chinese vendors.

analogmonster · Joined: May 30, 2011 Posts: 89 Location: Germany

dslocum · Joined: Jul 20, 2013 Posts: 19 Location: Toms River NJ

I had cross-posted this subject in ModWigglers and someone pointed out that 741s are INDEED still available. I must have done a search that was specific to LM741, not uA741.

They DO exist, so this is now a moot point. Thanks all for the help.