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LM741 Opamp

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shermaine

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Why is LM741 inappropriate as an internal opertaional amplifier in an IC? Is there any moddifications that can be done?
 
shermaine said:
Why is LM741 inappropriate as an internal operational amplifier in an IC? Is there any modifications that can be done?
What are you asking about a 741 opamp IC? :?:

It is inappropriate for applications today because its design is very old and newer, better, and cheaper opamps are available:
1) Much wider bandwidth.
2) Much lower noise.
3) Some are able to operate well with much lower supply voltages or a single supply.
4) Some have much lower supply current.
5) Some have FET inputs for much lower inputs bias current.
6) Most newer opamps are available as dual or quad opamps in one package.
7) Much better dual opamps are cheaper than a single 741.

About the only modification you can do to a 741 opamp is to throw away the lousy old thing and use a better opamp instead.
 
yup 741 was good at the time (ie it was the first real OPAMP) but there are soo much better ones out there

OPAMP of the month for me is the TLE2021
 
Styx said:
yup 741 was good at the time (ie it was the first real OPAMP) but there are soo much better ones out there

No, it wasn't the first 'real opamp' by a long way, but it was perhaps the first "idiot's opamp" because it was so simple to use. It's not very relevant though in the 21st century!.
 
Nigel Goodwin said:
Styx said:
yup 741 was good at the time (ie it was the first real OPAMP) but there are soo much better ones out there

No, it wasn't the first 'real opamp' by a long way, but it was perhaps the first "idiot's opamp" because it was so simple to use. It's not very relevant though in the 21st century!.

I wouldn't know, I wasn't even around when the 741 was even being superceeded :D
 
4electros said:
such as LM324 ( Low Power Quad Operational Amplifiers )
The LM324 is only 3 years younger than the 741 and is 34 years old today. It is also has a low bandwidth and high noise. Because it is low power it has terrible crossover distortion.
Mutsubishi copied the LM324 and explains the 3% crossover distortion (at a gain of 1, it is even worse at higher gain) and a method to reduce it.
 

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The uA709 Op-amp Preceeded the 741.
It Suffered from Latch-up problems, under certain Conditions.

As to the Working of the 741 today, There is Nothing wrong with it.
As long as you Don't need Really Low Noise or High Gain and Bandwidth.
And No, it also isn't Rail to rail operation.
But overall, it is still an industry standard as being a Very Reliable part. and Still in Production after All these Years.

Also, Depending on What your using an Op-amp for, Sometimes better op-amps with Excessive Speed and Bandwidth can also be a problem.

And you Can't really compare the LM324 to the 741. The 324 was made for a Single supply, opposed to a split supply.
 
audioguru said:
4electros said:
such as LM324 ( Low Power Quad Operational Amplifiers )
.
Mutsubishi copied the LM324 and explains the 3% crossover distortion (at a gain of 1, it is even worse at higher gain) and a method to reduce it.

What did you mean by explains 3% crossover distortion,did you mean that LM324 has a 3% distortion out of 741's?!

Would you like to give us general advise about using operational amplifiers?

thanks! :)
 
4electros said:
Would you like to give us general advise about using operational amplifiers?

Yes - use a more modern one than a 741, it will be cheaper, quieter, have more gain, have less distortion, and have a larger output swing. A 741 was a great chip when it was released, but that was a LONG, LONG time ago.
 
4electros said:
What did you mean by explains 3% crossover distortion,did you mean that LM324 has a 3% distortion out of 741's?!
Correct. To allow the amplifiers in an LM324 to have low supply current, the design uses NO bias current in the output transistors like normal amplifiers have. It has a constant current sink of only 50uA to operate Q5 and Q6 in the class-A mode to reduce the crossover distortion when the opamp doesn't have a load.
If the output is capacitively coupled or the opamp has a dual supply, then Q13 is never turned on until the negative-going load current exceeds 50uA. When the negative-going load current exceeds 50uA, then the drive voltage to the bases of Q5 and Q13 must suddenly change about 2.1V which causes severe crossover distortion.

To reduce crossover distortion, National recommends adding a load resistor to ground to provide more current for Q5 and Q6 to remain operating in the class-A mode.
Mitsubishi recommends adding a load resistor to the supply so that Q13 operates in the class-A mode.
Both recommendations result in the opamp using much more supply current.
 

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And don't you dare take your automobile out on the road it it's over 30 years old, gets lower fuel economy, has less horsepower and acceleration, doesn't have GPS capability and XM satellite radio. You know it won't get you where you need to go. And don't give me the excuse that it's your only vehicle, either!

Shermain, don't take seriously all this crap about the 741 being an antiquated component and how it shouldn't be used ONLY because there are so many better and cheaper devices available. I have about 150 741C op amps at my disposal. If my project will work just fine with a 741 I already own, why in the world would I want to spend anywhere from $0.57 to $2.56 plus shipping and/or gas mileage to buy one that won't make my circuit perform any better?

Why aren't these same clowns telling you that you should only be using 1% metal film resistors instead of carbon resistors -- they're newer and better. Why not 100% silver wire instead of copper? Why not insist on tantalum caps everywhere instead of aluminum electrolytics? Is everyone making sure that all their ICs are in ceramic, MILSPEC, hermetically-sealed packages?

Jeez.
 
Dean Huster said:
I have about 150 741C op amps at my disposal. If my project will work just fine with a 741 I already own, why in the world would I want to spend anywhere from $0.57 to $2.56 plus shipping and/or gas mileage to buy one that won't make my circuit perform any better?

That was hardly the point!, I too have a number of 741's already available (but NOT 150!), and I'd quite happily (and do) use them.

But most of these people are going out and BUYING a 741, at greater cost than a vastly better modern chip.

The same applies to PIC's, people are buying the long obselete 16F84, rather than paying less for it's replacement the 16F628?.

Your car analogy unfortunately doesn't work, because you can't buy a newly manufactured 'old car', particularly as they wouldn't be allowed to sell them (not meeting currenet legislation). But, given the choice, would you buy a modern, safe (or at least safer), fuel efficient, car - or would you prefer to spend more money on a modern replica of an old car, with much higher running costs, lower safety standards, and much lower spec (including a valve AM only radio).
 
In both the car analogy and with the subject of the 741, my comment is that if you have the item already and it works fine, don't run out and buy a spiffier new one that has performance specifications that won't affect the project.

As far as the car goes, what's less-expensive -- my old car that gets 25 mpg (excuse the English vs. ISO units here) but is paid for or a new model that gets 30 mpg but saddles me with a nasty 5-year loan and higher taxes? The new car will take a long time to make up the difference of 5 mpg and the purchase price.

The 741 was a great chip when it was released, you mentioned. It's age hasn't diminished that fact, really. At least you can still easily and inexpensively breadboard with the thing as opposed to some of these newer op amps that are only available in SMT.

I'm just a firm believer in using what I have rather than running out and buying new stuff. It's that penny-pinching upbringing, I guess.

Dean
 
I've purchased only one 741 opamp but thousands of better, cheaper ones. So my circuits operate better and saved me a penny-pinching fortune!

I don't bother with using a breadboard for prototypes. The datasheets show me what a part does and how. I just connect the circuit I've designed onto Veroboard and 99% work properly the 1st time. :lol:
 
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