"Chuck Harris" wrote in message
...
Norm Dresner wrote:


You're right -- there's nothing like the "real thing", unless there's
something better. One of the reasons that was given for not using a
simple
3-terminal regulator here was that the OpAmp-based regulator would
provide
much better regulation in general and better ripple rejection in
particular.
If that's really true, then how could a better Op Amp hurt? I can't
believe
that the designers of the circuit chose the 741 as the optimum device to
use
over dozens of Op Amps that hadn't been designed yet.

BTW, I've also found out that the OP-27 has +-22V specs too and I've got
those as well. It's got lower noise and offset voltage, higher slew
rate,
and wider bandwidth than the 741. Which of those do you think make it
less
suitable?

Norm


The higher slew rate and wider bandwidth will likely screw your circuit.
When the circuit was designed, and the board was layed out, it was done
with a 741. The things are very slow, and as such perfectly suited to
power supply use. With a faster opamp, you may find that your ciruit has
a tendency to oscillate, and to be bothered by powerline transients.

Or... it might work perfectly well. It is easy enough to try.

Do your circuit board a favor, and clip the pins off of the old IC flush
with its
body, and remove them one at a time... it is always easier on the board
than solder wick, or those hand held vacuum thingies. I even do that with
my PACE desoldering station if I don't need to save the chip.

-Chuck Harris

As soon as my eye is healed enough (from surgery) to be able to bend down
and see well enough to solder I'll give it a try.

Thanks for the desoldering tip.

Norm