What's a "jelly bean" processor? Trying to search for that just gets a bunch of hits about Android 4.1.
> Jellybean is a common term for components that you keep in your parts inventory for when your project just needs “a transistor” or “a diode” or “a mosfet”
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For many hobbyists, a Raspberry Pi or Arduino is a good example of a Jellybean. You buy 10x Raspberry Pis and stuff your drawer full of them, because they're cheap enough to do most tasks. You don't really know what you're going to use all 10x Rasp. Pi for, but you know you'll find a use of it a few weeks from now.
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At least, in my Comp. Engineering brain, I think N2222 transistors or 3904-transistors, or the 741 Op-amp. There are better op-amps and better transistors for any particular job. But I chose these parts because they're familiar, comfortable, cheap and well understood by a wide variety of engineers.
Well, not the 741 OpAmp anymore anyway. 741 was a jellybean back in the 12V days. Today I think 5V compatibility has become the standard voltage (because of USB). So 5V op-amps are a more important "jellybean".
I think your jellybean op-amps would more likely be TL072, LM358, or NE5532.
Maybe it was fully obsolete by that point, but high school + neighborhood libraries aren't exactly filled with up-to-date textbooks or the latest and greatest.
I remember that Radio Shack was still selling kits with 741 in them, as well as breadboards and common components... 12V wall-warts and the like. Online shopping was beginning to get popular, but I was still a mallrat who picked up components and dug through old Radio Shack manuals into 2005 or 2006.
It was the ability to walk around, and see those component shelves sitting there in Radio Shack that got me curious about the hobby and start researching it. I do wonder how modern children are supposed to get interested into hobbies now that malls are less popular (and electronic shops like Radio Shack are basically disappeared).
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I don't remember what we used in college. I knew that I was more selective and understood the kinds of problems various OpAmps had back then. Also you're not really rich enough to invest into a private stockpile of chips, and instead just use whatever the labs are stocked with in college.
LM358 is the jellybean that I keep in my drawer today. If you're curious. Old habits die hard though, I still think 741 as the jellybean even though it really is obsolete today.
https://www.intel.com/content/dam/www/public/us/en/documents...
Lets say you make a design that has +/- 1V error. On the 5V circuit, that's 20% error. But on the +/-12V circuit, it is only 4.1% error. (Going much better than 5% or 1% error is nonsensical. Most resistors you'll buy are 5% error, and capacitors are maybe +/- 20% error). So you can see, +/-1V error is acceptable on +/-12V circuits, but maybe unacceptable on 5V circuits.
If precision is important, there are 1% or 0.1% resistors available, as well as matched-resistors (which have say 1% error, but all the resistors have the same degree of error, so your "proportions" remain consistent. You can manually-match resistors together with an accurate ohm-meter as well)
As such, +/- 12V is simply easier to make "precise" electronics on. Of course, the downside is that you've got leakage all over the place (more voltage means more power-draw)
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But now its 2021. Most parts, even extremely cheap "Jellybean" parts like the LM358, have low errors and low-bias. And USB's popularity as a 5V delivery mechanism has grown, everyone has a USB plug somewhere to use as the basis of electricity experiments.
So while electronic engineers way back played with +/-12V, today the assumption is that you play with 0V to 5V.
If you are already putting buck converters everywhere, it makes sense to raise the voltage coming from the PSU, because you can reduce the current supplied by the PSU. Only the power supply will be running at 12V, almost everything else will be running at a lower voltage. (Would you rather supply 120W at 12V/10A or 5V/24A?)
Think Atmel AtMega parts, there are trillions of these in various roles. When you think of something like a 555 timer[1] that is now more cost effectively and capably replaced with an 8 pin micro-processor you can get an idea of the shift.
While these are rarely built on the "leading edge" process node, when a process node takes over for high margin chips, the previous node gets used for lower margin chips, which effectively does a shrink on their die increasing their cost (most of these chips seem to keep their performance specs fairly constant, preferring cost reduction over performance improvement.)
Anyway, the zillions of these chips in lots of different "flavors" are colloquially referred to as "jelly bean" chips.
> [1] Jelly Bean chips are those that are made in batches of 1 - 10 million with a set of functions that are fairly specific to their application.