Opamp replacement for varible PSU

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ifrythings

ifrythings

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Joined 2005
#1
I have a variable linear PSU 0-30V 0-3A varible current limiting, that uses the good old LM741CN opamp.

Now I'm woundering if it would work better with an opamp that has a high slew rate? The LM741CN has a slew rate of 0.5V/us which seems really slow to me.

If I should change it what would be the best one to put inplace of the 741?

It's a 8 pin Dip.

Thanks

Dave
 
#3
It depends on the particular circuit employed, but I don't think that a "faster" op-amp could improve performance. That's because it's probably further slowed down by means of external frequency compensation to achieve stability.
 
#4
ifrythings said:
Bump!!!

Nobody can recomeded a better op-amp for this supply? or did I post this in the wrong spot?

I know a lot of better dual op-amps but I need single op-amps for this psu and I have no Idea about the single ones.
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I think perhaps you are confusing things.

Some people believe that different op-amps have different "sounds" (apart from quantifyable differences in slew-rate, distortion etc) and spend time "op-amp rolling".

Power supplies, like most other non-audio electronics have no such baggage, although it may be that a faster amplifier could help reduce the output impedance at faster load changes, for example.

It would be impossible to comment on this without seeing the whole schematic.

Perhaps you could explain how/why you think the PSU could be made "better"? Or are you short of things to do? 😀 😀
 
#6
Eva said:
It depends on the particular circuit employed, but I don't think that a "faster" op-amp could improve performance. That's because it's probably further slowed down by means of external frequency compensation to achieve stability.
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I never thought about that.


cliff said:

although it may be that a faster amplifier could help reduce the output impedance at faster load changes, for example.
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Thats is what I was thinking about.


AndrewT said:
Hi,
faster and quieter and lower Zo and lower temp drift could each improve performance, but as said it depends very much on the circuit.

Post it.
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Would a higher supply rejection ratio help here too?

I'm sorry guys, I don't have a schematic for it, It is a pre-built one 🙁 . But if you really want it I can reverse engienier it.

I don't think that the powersupply would react quick enough if I were to hook up a SMPS, for less complex loads, it does fine, but I just don't think it can respond fast enough for testing SMPS on it.

I'm probly bull -sh****g myself into some other relm here so please tell me if I'm way off the board.

Thanks

Dave.
 
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