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| Why is the 741 op amp still produced? |
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| temperance:
Where I work we solely use the metal can version: https://www.mouser.be/ProductDetail/Texas-Instruments/LM741H-NOPB?qs=QbsRYf82W3G0muqZ4UBumg%3D%3D We have them mounted by people wearing pure silk gloves to not have fingerprints on the shiny cans. For many things you don't need fancy op amps. Some applications where the LM741 or it's dual version are being used today: -Current sensing in welding equipment. -Amplifiers in intercom systems. -Rectifiers in audio metering circuits. -Switching power supplies auxiliary functions. -Military and aerospace. My favourites are the LM358 and the LM324. The real question is: how many pieces do you need? One or two or a few million and what are the requirements. An LM741 or even lower spec op amp will do just fine when all you are asked to do is drive s speaker in an intercom system. Some manufacturers even produce op amps far worse than an LM741 because the industry needs very low cost amplifiers. Examples can be found in the catalogue of NJR. Companies producing products in quantities usually have an engineer doing nothing else then counting µCents just for fun. This engineer will even look at the tolerance of a 0402 resistor. Just because 20 million 5% resistors are cheaper than a 1% resistor. |
| VK3DRB:
Last time I used two 741's was 35 years ago when someone brought me an audiophile's pre-amplifier for me to fix. I cannot remember the brand, but it was high-end and overpriced. It has poorly designed PCB inside in that it used a discrete component layout with tightly packed vertically mounted PTH resistors all over the place with painted leads to prevent shorts. One channel worked, the other was distorted. Split rails. No schematic available either. I simply scraped the paint off the post-input equalising circuitry on the good channel and measured the gain using a 1kHz sinewave generator. I then laid two 8-pin DIP 741 op amps upside down and wired in a circuit around the pins and potted the 741's in epoxy. I did both channels because the owner might detect a quality difference between the two. The owner said it has never sounded so clear and he was delighted. Makes one wonder why they did use 741's in the first place, other than the "black magic" of using discrete components. Never needed to use a 741 since. I have used a lot of LM358's since. |
| T3sl4co1l:
A general note on technology -- older tech of some manner or another will almost never completely go away. Heh, hm, vacuum tubes, and horses for transportation, are probably two unusually good counterexamples. They still remain of course, but only at a tiny fraction of their peak glory, and mainly because of enthusiasts willing to bear the cost. It's fair that some stepping-stone technologies can be fully obsoleted, that's true, enthusiasts notwithstanding. :) But for everything that exists as a current basis for higher technology, it's never going away, no matter how integrated that higher technology is. Single BJTs and MOSFETs are still with us, as are op-amps and comparators, CD4000 and 74(LS)/HC logic, and all manner of MCUs from the 8051 (and even 4-bit machines, for that matter) to x86. Which, heh, x86 itself, I mean... :-DD (But not so much bit-serial machines, I think? They were great back in the days of serial memory -- rotating drum or delay line. Anyone know any current applications?) Meanwhile, we absolutely have CPUs with stacked Flash and DRAM dies, integrated switching regulators and all manner of peripherals and controllers, to realize insanely powerful SoCs in pocket-sized packages, with short bills of materials -- in a given product, they've displaced a whole host of other components, but they haven't displaced them elsewhere, and I suspect never will. :) And going further back, it's especially difficult to obsolete anything to do with handling of raw materials -- like ore mining and smelting will always be with us. The exact manner in which they are done, can vary -- compare electrowinning and refining of copper, to the blast furnace it replaced. And not that blast furnaces have gone away either, they're still king for iron as far as I know. Industrial forging is done in a manner and scale hard to imagine from antiquity, but it also strains the imagination to think of some kind of, say, 3D printing process that is able to produce a similar grain structure in as short a time. (But 3D printing also offers revolutionary opportunities in the design of intricate forms, otherwise-impossible cavities, and the use of difficult or otherwise impossible alloys and tempers, thanks to rapid fusion, directional solidification and powder metallurgy methods.) Tim |
| Circlotron:
--- Quote from: temperance link=topic=254270.msg3239684#msg3239684 ---My favourites are the LM358 and the LM324.ors are cheaper than a 1% resistor. --- End quote --- Yep, me too. One advantage the 741 does has over those two is the 741 has it's output transistors biased whereas the 358/324 has the bases of the output transistors simply strapped together. Good recipe for crossover distortion. You can of course add a pulldown resistor to the output, but yeah... |
| magic:
Then RC4558 is for you. Even seems to be cheaper on Mouser and it's a dual. Although this one has phase reversal AFAIK... |
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