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Tuesday, July 8, 2014

Finally! Dis-Intergrated Circuits! Discrete Component Op Amps!

That, my friends, is a discrete component version of the 741 op amp chip.  I like it!  No more mysterious miniature black boxes -- here's a "chip" that you can understand, troubleshoot, and modify.   Seven Forty Fun!

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  1. This is just repetitious, and using the latest trend to fund it.

    Op-amps existed in the days of tubes, probably for all those analog computers. Then they were modules, I think I still have a Burr-Brown op-amp around that's bigger than a small box of matches.

    Then ICs came along, really making op-amps popular. They took up less space, they did the job, you treated them like a black box. Way more was done with op-amps when they were ICs than in the previous days of tubes and modules.

    But I'd also point out that about 1974, there was an article in Radio Electronics about making your own op-amp. That was a period when op-amps were making big inroads, but the lowly 741 didn't have that great specs for audio, and better ones were more expensive and harder to get in small quantities. It was a couple of years before CMOS input and JFET input op-amps came along, raising the bandwidth along with other things without raising the cost.

    Anyway, the op-amp described in that RE article was intended for audio, get better performance by stepping back. It was an interesting period for audio, Walter Jung doing mods and writing about op-amps, The Audio Amateur probably already publishing, lots of high performance preamps, but building an op-amp first had the advantage of a consistent module to build the rest.

    I am vague about specific date, or author, it might have been Walter Jung. And the basic article may have been in The Audio Amateur before being published in Radio Electronics. May have also been a kit.

    The "Maker movement" needs to decide whether it's about making, or making money. This is a classic example. Someone didn't write an article about building your own op-amp, and maybe having a kit available on the side, they went to funding to build a kit so people could get excited about some novelty. The novelty seems to be the riding factor here, and yes, novelty sells more than if the target is some guy working away in his basement. But if the "Maker movement" is about making money, where does that leave people who haven't got to that stage? Most hobby electronic and amateur radio magazines gave better descriptions of how a project worked than "Make" magazine, and now that magazine doesn't even put the projects in the magazine, just the hype for the projects. That's no different than the days of the computer magazines after the program listings were banished from the pages, or those construction articles where you couldn't see a schematic before you sent away for it.

    "Make" is mostly hype, and that's not a good thing. Better to find the fewer people who are actually interested in such things than broaden it all by dumbing it down.

    Michael VE2BVW

  2. Must have been the 70's - I built a stereo amp with 4 such "IC's" from this or similar article. I made the modules on Veroboard, all connections to one edge, in less than an inch square. Well befoe internet, and I let it go at a Ham "Junk Sale" before realising it could be documented for an article. :(
    Dex ZL2DEX


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