How are legacy chips made these days? - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 16, 2025, 07:55:47 pm
content: Like the good old 741 op amp, it's still being made, right? I mean it's in stock at Digikey.Do these chips still meet the original specs like bandwidth, or they comfortably exceed all specs and they only make these opamps out of nostalgia, or for long-term users that won't change their designs for x-y-z reasons?The 741 datasheet for example has a bandwidth parameter given as 1.5MHz typical, with no maximum indicated.If I crack open a 50 year old 741 and a new one, will I see the same die and feature sizes?I ask because someone made a video buffer for vintage computers, like RGB with a 16MHz pixel rate, using 741s.My first instinct would have been it won't work very well at all, like at 1.5MHz bandwidth you're getting patches of color, nothing close to the resolution of 80 column text.But he says it works. Not well, but far better than I would have guessed.Was the 741 always exceeding its bandwidth even back then, hence the no maximum, or would that video circuit not work with a 50 year old 741?

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: August 16, 2025, 08:11:49 pm
content: Fellow EEVBlog member Noopy has an extensive semiconductor photo collection.Several of the most popular devices, the 741 most likely being one of them, have images taken from different manufacturers and different vintages.He even provides insightful comments on the features.Search for his name.

author: edavid
author_rank: Super Contributor
timestamp: August 16, 2025, 09:44:42 pm
content: Quote from: Alex Eisenhut on August 16, 2025, 07:55:47 pmNo.There are a bunch of die shots linked here:https://www.tinytransistors.net/tag/741/(Or you can also look at Noopy's as mentioned.)QuoteI call BS on this. The 741 typical slew rate spec is 0.5V/us, so in one pixel time it could only slew 31mV. Even if it were 10X faster, it still wouldn't work.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 16, 2025, 10:07:13 pm
content: Quote from: edavid on August 16, 2025, 09:44:42 pmThat was my thought as well. I've learned that in many cases when people tell me X works when I think X shouldn't, but it does, I can learn something. For all I know his setup is so bad that parasitic capacitance is letting most of the input through to the output and he's not interpreting his results correctly. In which case he's gonna do the learning...Why that person chose a 741 in 2025 when there must be about a thousand better choices eludes me.

author: amyk
author_rank: Super Contributor
timestamp: August 17, 2025, 05:25:33 am
content: What are the chances this person actually bought afake741 that's a remarked much newer, higher-bandwidth but cheaper part?

author: guenthert
author_rank: Frequent Contributor
timestamp: August 17, 2025, 09:08:30 am
content: Quote from: amyk on August 17, 2025, 05:25:33 amZilch? As mentioned, 741 are still being made and they are dirt cheap. There is no market forfake741. There might beunlicensed741, but that's a different story.The 741 is indeed generally a poor choice for new designs (and has been for 30 years or so). The supply (and output) voltages can be fairly high though, which warrants caution when attempting to 'upgrade' one.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 17, 2025, 09:37:58 am
content: Quote from: guenthert on August 17, 2025, 09:08:30 amNope. LM741 is a popular / well known type number and for some strange reason many hobbyists apparently still buy them. As a result, vendors of fake chips rub of type numbers of any opamp they can find and print lm741 on it. As long as the source of the part is unknown, testing it does not mean anything.In addition, have you seen the thread below?In short: Ti moved production of the good old TL074 to a different production line and changed the process from J-FET to MOS-FETs. This lowered power consumption and doubled the noise.https://www.eevblog.com/forum/beginners/what-tl074s-are-still-jfet/msg6003221/#msg6003221

author: magic
author_rank: Super Contributor
timestamp: August 17, 2025, 10:30:27 am
content: Quote from: guenthert on August 17, 2025, 09:08:30 amMarketplace sites like AliBayZon are flooded with cheapest Chinese LM358 clones which are fraudulently labeled as every possible opamp under the sun, including uA741 of course. See below, somebody even got LM393 comparators labeled as opampshttps://www.eevblog.com/forum/projects/whats-inside-the-cheapest-and-fakest-jellybean-opamps/In fact, if you go to AliExpress, it would be tricky to find a true uA741 there. Even ordering OPA134 doesn't guarantee that you will receive a 741, though I once did

author: David Hess
author_rank: Super Contributor
timestamp: August 17, 2025, 02:19:04 pm
content: Quote from: Alex Eisenhut on August 16, 2025, 07:55:47 pmThere are a lot of ICs built on the simple junction isolated NPN process responsible for the 741, so it is not going anywhere, including the 324, 339, and 555.QuoteThe parasitic capacitance of a junction isolated process limits performance. They also have features which are difficult to duplicate, like wide differential voltage range, unless a more complicated process with JFETs is used, and 30+ volt operation.