7 ms·

Choosing an op-amp for your project

170 points by zdw 2y ago

elcritch 2y ago
Great write up. And definitely skip the 60 year old models. Also valuable to look for is ESD protection. Many op amps have good 2kV static shock protection. Really sucks to have cascading failures due to touching your circuit and blowing an op amp. For some uses it’s also good to checkout input current bias.
- elcritch 2y ago
  Another bit I discovered is the quality of resistors. Pretty much any op amp circuit will use resistors. Often the resistors limit the static offsets. Don’t stick with 1% for analog circuits as 0.1% precision resistors are cheap and come with low temp drift as well.
f1shy 2y ago
To add to this discussion is useful the video or eevlog: https://www.youtube.com/watch?v=uq1DMWtjL2U https://www.youtube.com/watch?v=uq1DMWtjL2U where Dave discusses the "Jelly bean" op amps
perriera 2y ago
>f you’re designing a new op-amp circuit, here are some decent, all-around alternatives made in the 21st century None of the listed opamps would be an alternative to where an LM324 or TL071 are typically used - low cost, 20V-30V supply, infinite/guaranteed availability. They are 5V only and cost 10x as much.
- bratwurst3000 2y ago
  i build and repair audio electronics and the tl071 is used in abundance in audio circuits and is a bad choice imho. But good opamps for audio are at least a few dollars
  - Archit3ch 2y ago
    If you want the mirror the OpAmp distortion from the original units for authenticity/character, it makes sense to use the TL071, no?
    - shermantanktop 2y ago
      Based on my experience with vintage music electronics, it wouldn’t be good enough to use a component that just sounds bad like a TL071; it needs to be a TL071 so that the marketing copy can claim “vintage-correct parts.” At that point you are engineering with a completely different set of tradeoffs than would be expected for a modern ground-up design effort.
    - bratwurst3000 2y ago
      thats true. I forgot to mention i mean electronics from mid 90s onward. Even in higher class electronics. for example many of those 2000 euro upwards dj mixer use tl071 and even high end dac and soundcards. I replaced some of them with good opas and burrbrown opamps and for me it made , even if not big, audible changes to the better. But this could be my imagination. whatever i prefere some opamps in the range from 2-4 bucks. even if its only for the feeling…didnt measure it.
  - spamatica 2y ago
    Any suggestion for a (reasonably) good and cheap one for new designs?
    - nicolaslem 2y ago
      The book "Small Signal Audio Design" by Douglas Self has an entire 50 pages chapter on selecting opamps for audio. The chapter roughly ends with this quote: > One thing is obvious — the 5532 is still one of the great opamp bargains of all time.
    - bratwurst3000 2y ago
      i like the opa2134 pa , or in general the bur brown opa, on the expensive site and on the cheap one the ne5534.
- hn4352 2y ago
  Try the https://www.ti.com/product/TLV9301 https://www.ti.com/product/TLV9301 $0.5 @ 1s of units w/ modern specs and a 40V supply range.
peteforde 2y ago
I've watched the videos and agree that the OPA2323 does appear to sound amazing by subjective comparison to the TL071. However, it's not enough to say that it costs ~8.7x as much in local tokens because that doesn't reflect how much it costs as a percentage of the other components around it, many of which have a more profound impact on the outcome. This wouldn't stand as a good argument except that in many devices, you have a ceiling for how much your total BOM can cost before you've priced yourself out of competition. In the end, a 8.7x cost bump is a lot to swallow for a feature that most consumers are physically incapable of distinguishing between. Every time I've raised the possibility of using the fancy new chips, vastly more experienced engineers than me have come out of the woodwork to tell me that in almost all scenarios, the tradeoff between price and quality isn't worth it. Of course, if budget is not an issue, use the OPA2323. It really does sound great. Or more accurately, the degree to which it destroys good sound is as low as we can currently achieve. (This comment originally stated a 12x factor, but I was terrible at math.)
- Majromax 2y ago
  Is the cost delta really 12×? Looking at Mouser Canada, it looks like the cheapest 071 is the TL071CDR, at $0.138/each (Canadian) in quantities of 5k. The OPA2323IDDFR is $0.49 in the same quantity. > In the end, a 12x cost bump is a lot to swallow for a feature that most consumers are physically incapable of distinguishing between. I think that the performance of an op-amp should very rarely have user-visible effects. The more interesting question is whether the more expensive chip can make for a simpler design elsewhere. For example, can a rail-to-rail amplifier save the extra cost of needing charge pumps and split-rail design elsewhere? Also, not all domains should be cost-optimized. Hobbyist or prototyping work might best benefit from using a more expensive but more capable amplifier as a first choice, saving on the number of components that might need to be stocked in the home lab.
  - peteforde 2y ago
    All good points! And I am no expert. FWIW, here is what I was going off of, price wise: https://www.digikey.ca/en/products/detail/texas-instruments/TL071HIDBVR/14835784 https://www.digikey.ca/en/products/detail/texas-instruments/... https://www.digikey.ca/en/products/detail/texas-instruments/OPA2323IDR/22147099 https://www.digikey.ca/en/products/detail/texas-instruments/... In other words, the cheapest TL071 variant and the cheapest OPA2323 variant on Digikey Canada, in a quantity of 1 (ie wildly expensive). $0.31 vs $2.70 means that I shouldn't attempt math before coffee; 8.7x is still a big bump, although I acknowledge it's not the 12x I disinformationed earlier, with apologies to anyone reading.
kragen 2y ago
I found this post extremely interesting and informative, well above my expectations even given the eminence of its author. I'm not sure that everything in it is covered in The Art of Electronics — it's the kind of stuff the book covers, but I learned things from this post I didn't learn from the book. (But possibly it's information that's in the book that I just failed to absorb the last few times.) I was recently looking at opamps as alternatives to the LM324 and found some interesting-sounding parts, in particular for a poor man's SMU application (precision, low current, and voltage requirements, but not much bandwidth). Haven't tried any of them yet. Comments would be welcome. - LM324B: TI's improved LM324, with half the input offset voltage and otherwise improved ratings, and just as cheap, but still bipolar. - OPA4197 and family: three dollars but it's a quad RRIO 36V 10MHz opamp in a 14-SOIC with ±15nA input bias current, ±100μV max input offset voltage, and 120dB min CMRR. The datasheet makes it sound amazing for the price. The OPA177 seems like it would be better but pricier. - OP4177ARUZ: a 16-dollar quad 36V 1.3MHz opamp with ±2nA input bias current, 75μV max input offset voltage (at ±15V power supply), and min 120dB CMRR Then I decided I'd screwed up my design sketch by requiring one of the opamps to sink significant current very close to the negative rail, which is something even "rail-to-rail" opamps can't do; I was planning to use millivolts from ground to represent measured nanoamps. If you want to look at a simulation with idealized opamps, it's at https://tinyurl.com/2aomvpn5 https://tinyurl.com/2aomvpn5, but don't take it as exemplary in any sense; it's a novice design with novice mistakes (and I would be grateful in the unlikely case that someone took the trouble to point some of them out). I think I need to redesign the circuit as a bipolarity-supply circuit or something, or use a differential output for the current measurement, or rethink it entirely.
- dragontamer 2y ago
  > Then I decided I'd screwed up my design sketch by requiring one of the opamps to sink significant current very close to the negative rail, which is something even "rail-to-rail" opamps can't do; I was planning to use millivolts from ground to represent measured nanoamps. Get an OpAmp specifically designed for current sense applications. OpAmps for current sense applications have high accuracy near 0 Volts and Vos measured in single digit microvolts. Oh, you WILL lose bandwidth with these designs. So make sure you are allowed to be much much slower.
dragontamer 2y ago
Vos doesn't matter until it does. I find it surprising to see Vos mentioned as likely unimportant right next to CMRR, as CMRR and Vos are innately related in some circuits. In particular, any low voltage current sense circuit is going to require very precise Vos. Let's say you have a 0.01 Ohm current-sense resistor on a 5-Amp or so circuit. Your current-sense is now in the range of +/- 0.05Volts (!!!!). So a Vos of 0.005 would represent a 10% error. Likely too much for most applications. In effect, CMRR has become hyper-sensitive to Vos in this particular use case, to the point that Vos is suddenly the most important statistic. Fortunately, there are specially designed low-offset chopper or auto-zeroing OpAmps like MCP6V26 or whatever out there. MCP6V26 has Vos of 2uV, or in relatable terms... 0.000002 Volts (!!!!). Meaning it is more than sufficient at reliably making this current-sense application. Indeed, you can drop down to 0.0001Ohm resistance and still have high accuracy (and power savings compared to the earlier assumption). ------ Alas, nothing is ever free in life. Chopper Amps have noise issues and other designs have very very low bandwidth (which is truly an important statistic for most circuits). Choosing a chopper amp specifically is making a Vos tradeoff with Bandwidth. So only choose if you know what you are doing (aka, dealing with very low voltages and needing the precise zero).
- nine_k 2y ago
  For current measurement, I'd rather use a Hall sensor. But to measure the signal from that sensor a sensitive opamp is needed, and your comment applies :)
  - blackguardx 2y ago
    Using Hall-effect sensors to measure current isn’t that common when currents are in the uA to mA range. I’ve also never seen them used even for Amp range measurements when the application is purely on-board power supply meaurement.
    - nine_k 2y ago
      The example uses 5A. For mA range, of course not.
squarefoot 2y ago
Any comments on the LM4562? As per data sheet it appears to be really good for audio wrt noise and distortion, yet I see it rarely mentioned. https://www.ti.com/lit/ds/symlink/lm4562.pdf https://www.ti.com/lit/ds/symlink/lm4562.pdf
- formerly_proven 2y ago
  It and the LME49720 (same part) were discontinued a couple years ago along with the entire LME Overture series.
  - ckocagil 2y ago
    Potential replacements for ultra low THD would be: OPA1612, OPA1656 and OPA1642 with bipolar, cmos and jfet inputs respectively.
    - magic_smoke_ee 2y ago
      There's a massive (old) list of them in Horowitz & Hill TAOE 3e Table 8.3a p. 522. I'm sure you can just go to Digikey or Octopart and do a parameter search for high-voltage, low-noise, BJT-input op-amps too. If one wanted to "use a Ferrari to go the grocery store", they could always use a $20 AD797 or LT1115 for audio applications. :o)
      - ckocagil 2y ago
        I picked those particular chips is due to their extremely good performance at a reasonable cost. Check their THD against AD797 and LT1115! :)
  - squarefoot 2y ago
    You sure about the LM4562? I've just checked at TME, Mouser and Digikey, and all of them have many in stock. I's also marked as "nopb" so it could likely be a newer lead free version.
    - 2y ago
omgJustTest 2y ago
"Frequency response: The most important AC parameter of an op-amp is known as bandwidth gain product (fGBP or fGBWP). Standard, fully-compensated devices are designed to have an internal gain that rolls off proportionally to signal frequency. At fGBP, this gain is reduced to one:" "Stuff not to worry about: Despite what content-farmed articles imply, most of the other parameters in the spec can be usually glanced over. For example, the exact value of open-loop gain (AOL) is almost never of real consequence; the same goes for input offset voltage (VOS) — even in high-precision instruments, the absolute value is less important than drift over time. In any case, the parameters are usually only eyeballed in most specs, so if you’re building sensitive instrumentation, you will still need to calibrate the readings using a known reference." I rarely think about fGBP and AOL as separate ideas, the author could make the point more directly by saying they are related and that one is easier to select from a single decimal value. AOL or fGBP is a primary design consideration.
buescher 2y ago
Be aware in a microcontroller design, an lm324-type op amp might outperform the on-chip ADC you’re using anyway. Even the cheapest op amps from major players are better characterized and specified on their data sheets than most microcontroller ADCs. There’s no virtue in spending other people’s money and supply chain risk to use a “better” part just because it wins a bench race or it’s newer or whatever.
- pythonguython 2y ago
  What does it mean for an op amp to outperform an ADC?
  - buescher 2y ago
    It can have wider bandwidth, lower noise+distortion, smaller Vos, maybe other things I'm not recalling off the top of my head. In practical terms, you might not be able to run any test with the ADC that can find the limits of the op amp.
bsder 2y ago
I'm really disappointed that the article didn't mention what is probably the single most important characteristic in an opamp when being chosen by an amateur: Unity gain stable Sure, the other characteristics are important, but a whole bunch of circuits that beginners are likely to use rely on opamps being unity gain stable. If they're not unity gain stable, the circuit will do very weird things, and a beginner won't know why. Of course, debugging issues like that are how you eventually become an expert.
HelloUsername 2y ago
Previous "discussion" https://news.ycombinator.com/item?id=39944839 https://news.ycombinator.com/item?id=39944839 April 2023
bnetd 2y ago
[dead]

170 points by zdw 2y ago

Great write up. And definitely skip the 60 year old models. Also valuable to look for is ESD protection. Many op amps have good 2kV static shock protection. Really sucks to have cascading failures due to touching your circuit and blowing an op amp. For some uses it’s also good to checkout input current bias.

elcritch 2y ago
Another bit I discovered is the quality of resistors. Pretty much any op amp circuit will use resistors. Often the resistors limit the static offsets. Don’t stick with 1% for analog circuits as 0.1% precision resistors are cheap and come with low temp drift as well.

f1shy 2y ago

To add to this discussion is useful the video or eevlog: https://www.youtube.com/watch?v=uq1DMWtjL2U https://www.youtube.com/watch?v=uq1DMWtjL2U where Dave discusses the "Jelly bean" op amps

perriera 2y ago

>f you’re designing a new op-amp circuit, here are some decent, all-around alternatives made in the 21st century None of the listed opamps would be an alternative to where an LM324 or TL071 are typically used - low cost, 20V-30V supply, infinite/guaranteed availability. They are 5V only and cost 10x as much.

bratwurst3000 2y ago
i build and repair audio electronics and the tl071 is used in abundance in audio circuits and is a bad choice imho. But good opamps for audio are at least a few dollars
- Archit3ch 2y ago
  If you want the mirror the OpAmp distortion from the original units for authenticity/character, it makes sense to use the TL071, no?
  - shermantanktop 2y ago
    Based on my experience with vintage music electronics, it wouldn’t be good enough to use a component that just sounds bad like a TL071; it needs to be a TL071 so that the marketing copy can claim “vintage-correct parts.” At that point you are engineering with a completely different set of tradeoffs than would be expected for a modern ground-up design effort.
  - bratwurst3000 2y ago
    thats true. I forgot to mention i mean electronics from mid 90s onward. Even in higher class electronics. for example many of those 2000 euro upwards dj mixer use tl071 and even high end dac and soundcards. I replaced some of them with good opas and burrbrown opamps and for me it made , even if not big, audible changes to the better. But this could be my imagination. whatever i prefere some opamps in the range from 2-4 bucks. even if its only for the feeling…didnt measure it.
- spamatica 2y ago
  Any suggestion for a (reasonably) good and cheap one for new designs?
  - nicolaslem 2y ago
    The book "Small Signal Audio Design" by Douglas Self has an entire 50 pages chapter on selecting opamps for audio. The chapter roughly ends with this quote: > One thing is obvious — the 5532 is still one of the great opamp bargains of all time.
  - bratwurst3000 2y ago
    i like the opa2134 pa , or in general the bur brown opa, on the expensive site and on the cheap one the ne5534.
hn4352 2y ago
Try the https://www.ti.com/product/TLV9301 https://www.ti.com/product/TLV9301 $0.5 @ 1s of units w/ modern specs and a 40V supply range.

peteforde 2y ago

I've watched the videos and agree that the OPA2323 does appear to sound amazing by subjective comparison to the TL071. However, it's not enough to say that it costs ~8.7x as much in local tokens because that doesn't reflect how much it costs as a percentage of the other components around it, many of which have a more profound impact on the outcome. This wouldn't stand as a good argument except that in many devices, you have a ceiling for how much your total BOM can cost before you've priced yourself out of competition. In the end, a 8.7x cost bump is a lot to swallow for a feature that most consumers are physically incapable of distinguishing between. Every time I've raised the possibility of using the fancy new chips, vastly more experienced engineers than me have come out of the woodwork to tell me that in almost all scenarios, the tradeoff between price and quality isn't worth it. Of course, if budget is not an issue, use the OPA2323. It really does sound great. Or more accurately, the degree to which it destroys good sound is as low as we can currently achieve. (This comment originally stated a 12x factor, but I was terrible at math.)

Majromax 2y ago
Is the cost delta really 12×? Looking at Mouser Canada, it looks like the cheapest 071 is the TL071CDR, at $0.138/each (Canadian) in quantities of 5k. The OPA2323IDDFR is $0.49 in the same quantity. > In the end, a 12x cost bump is a lot to swallow for a feature that most consumers are physically incapable of distinguishing between. I think that the performance of an op-amp should very rarely have user-visible effects. The more interesting question is whether the more expensive chip can make for a simpler design elsewhere. For example, can a rail-to-rail amplifier save the extra cost of needing charge pumps and split-rail design elsewhere? Also, not all domains should be cost-optimized. Hobbyist or prototyping work might best benefit from using a more expensive but more capable amplifier as a first choice, saving on the number of components that might need to be stocked in the home lab.
- peteforde 2y ago
  All good points! And I am no expert. FWIW, here is what I was going off of, price wise: https://www.digikey.ca/en/products/detail/texas-instruments/TL071HIDBVR/14835784 https://www.digikey.ca/en/products/detail/texas-instruments/... https://www.digikey.ca/en/products/detail/texas-instruments/OPA2323IDR/22147099 https://www.digikey.ca/en/products/detail/texas-instruments/... In other words, the cheapest TL071 variant and the cheapest OPA2323 variant on Digikey Canada, in a quantity of 1 (ie wildly expensive). $0.31 vs $2.70 means that I shouldn't attempt math before coffee; 8.7x is still a big bump, although I acknowledge it's not the 12x I disinformationed earlier, with apologies to anyone reading.

kragen 2y ago

I found this post extremely interesting and informative, well above my expectations even given the eminence of its author. I'm not sure that everything in it is covered in The Art of Electronics — it's the kind of stuff the book covers, but I learned things from this post I didn't learn from the book. (But possibly it's information that's in the book that I just failed to absorb the last few times.) I was recently looking at opamps as alternatives to the LM324 and found some interesting-sounding parts, in particular for a poor man's SMU application (precision, low current, and voltage requirements, but not much bandwidth). Haven't tried any of them yet. Comments would be welcome. - LM324B: TI's improved LM324, with half the input offset voltage and otherwise improved ratings, and just as cheap, but still bipolar. - OPA4197 and family: three dollars but it's a quad RRIO 36V 10MHz opamp in a 14-SOIC with ±15nA input bias current, ±100μV max input offset voltage, and 120dB min CMRR. The datasheet makes it sound amazing for the price. The OPA177 seems like it would be better but pricier. - OP4177ARUZ: a 16-dollar quad 36V 1.3MHz opamp with ±2nA input bias current, 75μV max input offset voltage (at ±15V power supply), and min 120dB CMRR Then I decided I'd screwed up my design sketch by requiring one of the opamps to sink significant current very close to the negative rail, which is something even "rail-to-rail" opamps can't do; I was planning to use millivolts from ground to represent measured nanoamps. If you want to look at a simulation with idealized opamps, it's at https://tinyurl.com/2aomvpn5 https://tinyurl.com/2aomvpn5, but don't take it as exemplary in any sense; it's a novice design with novice mistakes (and I would be grateful in the unlikely case that someone took the trouble to point some of them out). I think I need to redesign the circuit as a bipolarity-supply circuit or something, or use a differential output for the current measurement, or rethink it entirely.

dragontamer 2y ago
> Then I decided I'd screwed up my design sketch by requiring one of the opamps to sink significant current very close to the negative rail, which is something even "rail-to-rail" opamps can't do; I was planning to use millivolts from ground to represent measured nanoamps. Get an OpAmp specifically designed for current sense applications. OpAmps for current sense applications have high accuracy near 0 Volts and Vos measured in single digit microvolts. Oh, you WILL lose bandwidth with these designs. So make sure you are allowed to be much much slower.

dragontamer 2y ago

Vos doesn't matter until it does. I find it surprising to see Vos mentioned as likely unimportant right next to CMRR, as CMRR and Vos are innately related in some circuits. In particular, any low voltage current sense circuit is going to require very precise Vos. Let's say you have a 0.01 Ohm current-sense resistor on a 5-Amp or so circuit. Your current-sense is now in the range of +/- 0.05Volts (!!!!). So a Vos of 0.005 would represent a 10% error. Likely too much for most applications. In effect, CMRR has become hyper-sensitive to Vos in this particular use case, to the point that Vos is suddenly the most important statistic. Fortunately, there are specially designed low-offset chopper or auto-zeroing OpAmps like MCP6V26 or whatever out there. MCP6V26 has Vos of 2uV, or in relatable terms... 0.000002 Volts (!!!!). Meaning it is more than sufficient at reliably making this current-sense application. Indeed, you can drop down to 0.0001Ohm resistance and still have high accuracy (and power savings compared to the earlier assumption). ------ Alas, nothing is ever free in life. Chopper Amps have noise issues and other designs have very very low bandwidth (which is truly an important statistic for most circuits). Choosing a chopper amp specifically is making a Vos tradeoff with Bandwidth. So only choose if you know what you are doing (aka, dealing with very low voltages and needing the precise zero).

nine_k 2y ago
For current measurement, I'd rather use a Hall sensor. But to measure the signal from that sensor a sensitive opamp is needed, and your comment applies :)
- blackguardx 2y ago
  Using Hall-effect sensors to measure current isn’t that common when currents are in the uA to mA range. I’ve also never seen them used even for Amp range measurements when the application is purely on-board power supply meaurement.
  - nine_k 2y ago
    The example uses 5A. For mA range, of course not.

squarefoot 2y ago

Any comments on the LM4562? As per data sheet it appears to be really good for audio wrt noise and distortion, yet I see it rarely mentioned. https://www.ti.com/lit/ds/symlink/lm4562.pdf https://www.ti.com/lit/ds/symlink/lm4562.pdf

formerly_proven 2y ago
It and the LME49720 (same part) were discontinued a couple years ago along with the entire LME Overture series.
- ckocagil 2y ago
  Potential replacements for ultra low THD would be: OPA1612, OPA1656 and OPA1642 with bipolar, cmos and jfet inputs respectively.
  - magic_smoke_ee 2y ago
    There's a massive (old) list of them in Horowitz & Hill TAOE 3e Table 8.3a p. 522. I'm sure you can just go to Digikey or Octopart and do a parameter search for high-voltage, low-noise, BJT-input op-amps too. If one wanted to "use a Ferrari to go the grocery store", they could always use a $20 AD797 or LT1115 for audio applications. :o)
    - ckocagil 2y ago
      I picked those particular chips is due to their extremely good performance at a reasonable cost. Check their THD against AD797 and LT1115! :)
- squarefoot 2y ago
  You sure about the LM4562? I've just checked at TME, Mouser and Digikey, and all of them have many in stock. I's also marked as "nopb" so it could likely be a newer lead free version.
  - 2y ago

omgJustTest 2y ago

"Frequency response: The most important AC parameter of an op-amp is known as bandwidth gain product (fGBP or fGBWP). Standard, fully-compensated devices are designed to have an internal gain that rolls off proportionally to signal frequency. At fGBP, this gain is reduced to one:" "Stuff not to worry about: Despite what content-farmed articles imply, most of the other parameters in the spec can be usually glanced over. For example, the exact value of open-loop gain (AOL) is almost never of real consequence; the same goes for input offset voltage (VOS) — even in high-precision instruments, the absolute value is less important than drift over time. In any case, the parameters are usually only eyeballed in most specs, so if you’re building sensitive instrumentation, you will still need to calibrate the readings using a known reference." I rarely think about fGBP and AOL as separate ideas, the author could make the point more directly by saying they are related and that one is easier to select from a single decimal value. AOL or fGBP is a primary design consideration.

buescher 2y ago

Be aware in a microcontroller design, an lm324-type op amp might outperform the on-chip ADC you’re using anyway. Even the cheapest op amps from major players are better characterized and specified on their data sheets than most microcontroller ADCs. There’s no virtue in spending other people’s money and supply chain risk to use a “better” part just because it wins a bench race or it’s newer or whatever.

pythonguython 2y ago
What does it mean for an op amp to outperform an ADC?
- buescher 2y ago
  It can have wider bandwidth, lower noise+distortion, smaller Vos, maybe other things I'm not recalling off the top of my head. In practical terms, you might not be able to run any test with the ADC that can find the limits of the op amp.

bsder 2y ago

I'm really disappointed that the article didn't mention what is probably the single most important characteristic in an opamp when being chosen by an amateur: Unity gain stable Sure, the other characteristics are important, but a whole bunch of circuits that beginners are likely to use rely on opamps being unity gain stable. If they're not unity gain stable, the circuit will do very weird things, and a beginner won't know why. Of course, debugging issues like that are how you eventually become an expert.

HelloUsername 2y ago

Previous "discussion" https://news.ycombinator.com/item?id=39944839 https://news.ycombinator.com/item?id=39944839 April 2023

bnetd 2y ago

[dead]