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Comment by kens | Hacker News Reader

Any other suggestions for common yet generally unknown chips?

The NE555-timer is quite a cool little thing.

More common operational amplifiers are also worth looking into (TL072 is one of my favorites).

Lastly, the 7400-series logic chips are SO interesting. If you need the programmer's version of a jigsaw puzzle, try to build somewhat advanced designs using those. It's very fun and a good learning experience (although hard!).

This guy is building a computer on a breadboard – very intersting indeed: https://www.youtube.com/channel/UCS0N5baNlQWJCUrhCEo8WlA

NE555 is not "unknown" (most popular chip in the entire history of electronic engineering), 74xx and TL072 are not unknown either, anyone who knows a little bit of hardware knows the chip.

TL431 is popular yet unknown to most people outside the world of switched-mode power supply. I think the OP wants some popular yet relatively less-known chip to those who is outside of the field.

Thanks for the suggestions. Take a look at project5474.org if you want to see the internals of many 7400-series chips explained. Also, I've done a 555 timer teardown: http://www.righto.com/2016/02/555-timer-teardown-inside-worl...

Maxim's MAX038 (no relation with the 8038), a single chip analog multi waveform generator that goes from 0.1Hz to 20 MHz. Maxim discontinued it in the early 2000s but never replaced it.

https://www.maximintegrated.com/en/products/analog/clock-gen...

This is a good one, endless number of function generator circuits have been built around MAX038, I have a MAX038-based function generator on my desk right now. It's an analog generator and its stability is nowhere near a PLL/DDS-based generator, but it was a robust solution for a low-cost generator.

8051 ( https://en.wikipedia.org/wiki/Intel_MCS-51 ).

Still probably the most common microcontroller in existence, just because it's embedded in so many other ICs. 40 years old this year.

It's amazing how many of those old chips are still out there, but deep inside something else. I came across a 6502 embedded in a sensor SOC about 3 years ago. A 6502 for goodness sake.

Any of the zillion stm8 variants that surround us every where.

Yay for STM8. Cheap as dirt especially for how capable they are, and pretty sweet architecture for an 8 bit.

No GCC support, only 6 registers.. meh.

I think AVR is most friendliest from all 8 bit architectures.

Most 8-bit machines are historical and suffered from the technological limitation of its time, they usually have few registers, an accumulator-based architecture, no multiplication/division instructions, limited addressing mode (especially, no efficient base+addr). So in general, they are not suitable for compiled languages, and hand-tuned assembly is required for good performance. But it actually makes sense for mass-produced applications when simplicity and cost are important. On the other hand, I believe the AVR is one of the only major 8-bit architectures designed using a modern approach, specially optimized for modern C-based programming.

STM8 is a fairly new design although with some similarities to the 6502 and 6800. It does have multiply and divide instructions. It also has a plethora of addressing modes:

    ld a, #42        ; immediate. C constants
    ld a, var        ; direct. C globals and statics
    ld a, (sp, 4)    ; sp relative. C locals and arguments
    ld a, (x)        ; indirect. C *ptr (ptr in register)
    ld a, (x, 42)    ; indexed indirect. C ptr->foo (ptr in register)
    ld a, [ptr]      ; memory indirect. C *ptr (ptr in memory)
    ld a, ([ptr],x)  ; indexed memory indirect. C ptr->foo (ptr in memory)

There are more, but mainly variations in width and PC relative jumps.

Thanks for the correction.

SDCC is the open source compiler of choice for stm8. It's not GCC, but it's enough.

I'd be tempted to agree about the registers except that it takes wider instructions to encode the registers used so a well thought out accumulator based architecture can result in very compact code. stm8 has a lot of one byte instructions and most except for branches and word operations are single cycle as well.

UC2842/3842 (Primary side of a Flyback SMPS), versus TL431 which is on the secondary side.

Power supplies shipped in the past 10 years are most likely using an Onsemi variant of TI UC2842/3842.

Back in the days of tape recorders/players it would be the operational transconductance amplifier like the NE5517.

LM13700 transconductance amplifier; simple chip, decades of history; used in lots of (musical) synthesizers.

TL494. Up till very recent times was widely used in all kinds of PSUs, especially in AT ones.

LM358 op-amp?

I learned about those while google searching every component on my first Arduino in hopes to better understand how the thing worked.

Yeah. That and the LM393/LM339 type comparator-not exactly unknown though. But if I see those used appropriately in a circuit, it's the opposite effect of seeing 741 op-amps and 555 timers and TIP120 transistors.

Another one - the 33063/34063 type low-voltage DC/DC switchers. Like the TL431, hobbyists almost never use them but they're all over the place.

I'm a big fan of the LT3574 switching regulator[1]. Makes it very easy to split an input supply out to dual rails for op-amps, or just for general regulation. It provides an isolated output without needing optoisolators or a sense winding on the transformer. And since they're flyback converters they can output a voltage above or below the input, allowing for wide variation in the input needed. And in typical LT fashion the datasheet is extremely thorough and well-written. Including a step-by-step design example. And plenty of reference designs. I use the +-12V output one quite a bit for powering op-amps, it lets me make use of the fixed 5V output third channel on my bench supply!

Not the cheapest though, about $7 each in qt1 on DigiKey, but that's rarely an issue at the hobby scale. And the ability to use a cheaper transformer and not need an optoisolator can make it save BOM cost even at large scale production.

[1] https://www.analog.com/media/en/technical-documentation/data...

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