The History of the Invention of the OP-AMP. - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: June 08, 2024, 11:01:09 pm
content: Would you believe that initially, the patent was initially rejected, took 9 years to pass, and everyone thought the concept itself was a stupid idea...

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 09, 2024, 03:55:29 am
content: Well, almost everyone thought that Ohm's law was a stupid idea, too, when he came up with it.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: June 09, 2024, 06:23:26 pm
content: Quote from: BrianHG on June 08, 2024, 11:01:09 pm“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.”--Arthur Schopenhaur

author: KE5FX
author_rank: Super Contributor
timestamp: June 09, 2024, 06:24:43 pm
content: Same for the general concept of negative feedback.One funeral at a time...

author: TimFox
author_rank: Super Contributor
timestamp: June 09, 2024, 06:33:24 pm
content: Loebe Julie designed the WW II op amp (with octal tubes) that led to Philbrick’s commercial product using 9-pin miniature tubes. I read one version of that story (in EDN?) that compared the 6SL7 octal dual triodes to the 12AX7 miniature dual “high micron”  triodes.

author: coppercone2
author_rank: Super Contributor
timestamp: June 09, 2024, 07:05:01 pm
content: i think the early warning radar networks used massive banks of these vacuum op-amps in the communication grid for the US military in like the 50's and there was massively intense effort to miniaturize that communication backbone

author: TimFox
author_rank: Super Contributor
timestamp: June 09, 2024, 07:29:23 pm
content: I think that system used (then) massive vacuum tube digital computers.The SAGE computers were active into the 1980s.For reliability, each system had two identical units that were switched periodically to allow maintenance.

author: coppercone2
author_rank: Super Contributor
timestamp: June 09, 2024, 08:17:27 pm
content: I think I heard these were used for the communications circuits between sage stations (not the processor, which is digital). like for amplfiiers, conditioning, etc. Modem front ends or something. I Heard about cabinets full of these from someone teaching

author: Kleinstein
author_rank: Super Contributor
timestamp: June 09, 2024, 08:48:17 pm
content: Two important use case where analog computers and regulator circuits.The amplifiers with feedback have a lot overlap with control theory.Because of the relatively high price and limited drive the early OP-amps where not so much a thing as just amplifiers. So while better amplifiers where a reason to start with amplifier feedback, it was more a later thing to use operational amplifiers as just amplifiers, especially not if many of those where needed.In the video the comparison with modern types is odd - modern one can vary quite a bit and it makes little sense to mix the properties of different types. E.g. 85 µA would likely be more like 1 MHz GBW, definitely not 1.5 GHz. So one should use one "modern" chip (e.g. TL071 or MCP6001) as a comparison.

author: BrianHG
author_rank: Super Contributor
timestamp: June 11, 2024, 05:11:47 pm
content: This video describes how an op-amp is designed from the transistor up. From the simple beginnings to the higher end super gain sensitive devices with great power supply rejection.

author: magic
author_rank: Super Contributor
timestamp: June 11, 2024, 11:03:50 pm
content: Not bad, but at 8:07 you probably meant an NPN.PS. Genuinely great PSRR is achieved only by opamps which reference the compensation cap to ground rather than a supply rail

author: BrianHG
author_rank: Super Contributor
timestamp: June 12, 2024, 12:16:24 am
content: Quote from: magic on June 11, 2024, 11:03:50 pmNice catch....I added a comment on the Youtube's video link.

author: EPAIII
author_rank: Super Contributor
timestamp: June 14, 2024, 08:48:25 am
content: It may be a wonderful video. But I turned it off when I saw that the gentleman's name was not capitalized. Why was he insulted like that?