Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why do electronic components have such odd values? (2021)

digilent.com

Post reply on HN
Print view View original

151–160 of 168 posts

Re: Why do electronic components have such odd values? (2021)

#151

Post by nomel »

Dylan16807 wrote: post #103
nomel wrote: post #102

Earlier quoted context omitted.

I'm sorry, but it's incorrect, as stated. It's a false statement that has no relation to reality, with the context provided. Staying the same, as a percentage , is not "going down". If you add two things with error together, the absolute tolerance adds. The relative tolerance (percentage) may stay the same, or even reduce if you mix in a better tolerance part, but, as stated, it's incorrect. It's a common misundersta…

It only stays the same if you have the worst luck. > You can't use population statistics for low sample sizes with any meaning Yes you can. I can say a die roll should not be 2, but at the same time I had better not depend on that. Or more practically, I can make plans that depend on a dry day as long as I properly consider the chance of rain. > In my career, I’ve seen this exact misunderstanding cause many millions…

I've repeatedly used a certain words in what I wrote, since it has incredible meaning in the manufacturing and engineering world, which is the context we're seeking within. It's a word that determines the feasibility of a design in mass production, and a metric for if an engineer is competent or not: determinism. That is the goal of a good design.

> It only stays the same if you have the worst luck.

And, you will get that "worst luck" thousands of times in production, so you must accommodate it. Worst off, as others have said, the distributions are not normal. Most of the removed from the population, and sold at a premium. There's a good chance your components will be close to +5% or -5%

> Yes you can. I can say a die roll should...

No you cannot. Not in the context we're discussing. If you make an intentional decision to rely on luck, you're intentionally deciding to burn some money by scrapping a certain percentage of your product. Which is why nobody makes that decision. It would be ridiculous because you know the worst case, so you can accommodate it in your design. You don't build something within the failure point (population statistics). You don't build something at the failure point (tolerance), you make the result of the tolerance negligible in your design.

> Sounds like they calculated the probabilities incorrectly.

Or, you could look at it as being a poorly engineered system that couldn't accommodate the components they selected, where changing the values of some same-priced periphery components would have eliminated it completed.

Relying on luck for a device to operate is almost never a compromise made. If that is a concern, then there's IQC or early testing to filter out those parts/modules, to make sure the final device is working with a known tolerance that the design was intentionally made around.

Your perspective is very foreign to the engineering/manufacturing world, where determinism is the goal, since non-determinism is so expensive.

Re: Why do electronic components have such odd values? (2021)

#152

Post by tuetuopay »

hathawsh wrote: post #93
picture wrote: post #87

Earlier quoted context omitted.

Have you tried 10 kΩ for LED and FET pull down? 100 Ω sounds like way too much current for modern LEDs. I often end up using 100 kΩ especially for green LEDs. They are very visible under indoor lighting even with 1 MΩ and 3.3 V supply. For pulling down FETs, you want something in the range of 10 kΩ. 10 MΩ sounds way too high, which makes your circuit sensitive to being touched or affected by moisture, especially if t…

Are you sure all those numbers are in the right ballpark? With a 3.3V supply and a 1 MΩ resistor, the most current you can get from that circuit is in the neighborhood of 3μA, and that's ignoring the LED voltage drop. I would think the LED won't be visible until you're around the mA range. Or are some LEDs visible in the low μA range?

Modern LEDs light up with incredibly low currents. In a RF noisy environment, I've often seen LEDs glow just by touching one side with a wire and the other to ground. Just the parasitic from such a crude antenna was enough.

Of course as stated by another comment, our eyes are also incredible, and can pick up very faint amount of light.

Re: Why do electronic components have such odd values? (2021)

#153

Post by bsder »

anticensor wrote: post #121
bsder wrote: post #88

Earlier quoted context omitted.

Mostly, no. Nobody except for expensive precision resistor companies are actually measuring resistors more than statistically. The resistors are manufactured so that they are "guaranteed by manufacturing" such that the outliers are 1%, 5%, 10%, etc. And they do statistical checks on batches, but not really looking for the 10% outlier (which is stupendously rare and very difficult to catch) but looking for slight drif…

They should still bin, so that each individual resistor gets the highest price possible by the virtue of its classification, even if the binning is costly.

SMT resistors in bulk are a fraction of a penny.

Tester time FAR outweighs any gain you could get by binning.

Re: Why do electronic components have such odd values? (2021)

#154

Post by Dylan16807 »

nomel wrote: post #151
Dylan16807 wrote: post #103

Earlier quoted context omitted.

It only stays the same if you have the worst luck. > You can't use population statistics for low sample sizes with any meaning Yes you can. I can say a die roll should not be 2, but at the same time I had better not depend on that. Or more practically, I can make plans that depend on a dry day as long as I properly consider the chance of rain. > In my career, I’ve seen this exact misunderstanding cause many millions…

I've repeatedly used a certain words in what I wrote, since it has incredible meaning in the manufacturing and engineering world, which is the context we're seeking within. It's a word that determines the feasibility of a design in mass production, and a metric for if an engineer is competent or not: determinism. That is the goal of a good design. > It only stays the same if you have the worst luck. And, you will get…

> If you make an intentional decision to rely on luck, you're intentionally deciding to burn some money by scrapping a certain percentage of your product. Which is why nobody makes that decision.

Now this is complete nonsense. Lots of production processes do that. It depends on the cost of better tooling and components, and the cost of testing.

And... the actual probabilities! You're right that you can't assume a normal distribution. But that wouldn't matter if this was such a strict rule because normal distributions would be forbidden too.

Determinism is a good goal but it's not an absolute goal and it's not mandatory. You are exaggerating its importance when you declare any other analysis as "complete nonsense".

> since non-determinism is so expensive.

But your post gives off some pretty string implications that you need a 0% defect rate, and that's not realistic either. There's a point where decreasing defects costs more than filtering them. This is true for anything, including resistors. It's just that high quality resistors happen to be very cheap.

Re: Why do electronic components have such odd values? (2021)

#155

Post by SAI_Peregrinus »

galaxyLogic wrote: post #124
SAI_Peregrinus wrote: post #114

Earlier quoted context omitted.

And that's why the really precise resistors are so damn expensive. E.g. VPG makes a 10k 1/5W 0.001% tolerance ±0.2ppm/°C, but they're $116 each with a minimum order quantity of 25 on DigiKey (so $2900 minimum purchase). They've got a really expensive meter for their trimming setup!

I see. I guess that's why high-end audio is so expensive

Ha! No, they're not using metrology resistors, just ripping people off.

Re: Why do electronic components have such odd values? (2021)

#156

Post by galaxyLogic »

klodolph wrote: post #147
matheusmoreira wrote: post #143

Earlier quoted context omitted.

> For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. Is there a reason why they don't just use digital audio everywhere and convert to analog as late as possible? Inside the speakers for example? I mean, digital audio is pretty much perfect. Why are analog audio signals still a thing? People actually pay tho…

My speakers convert digital to analog. They have ethernet jacks in the back. Maybe you bought the wrong speakers? Stepping back for a moment… you see digital interconnects in high-end pro audio gear, using systems like Dante. These systems are NOT simple. When you have multiple digital audio systems connected together, you have to worry about whether they are all running from the same clock, or whether you can conver…

Right and isn't it the case that good quality D/A-converters still cost much money. So if you want every speaker to have them, and you want many speakers to get an immersive sound then "digital loudspeakers" can become expensive?

Re: Why do electronic components have such odd values? (2021)

#157

Post by galaxyLogic »

matheusmoreira wrote: post #143
atoav wrote: post #126

Earlier quoted context omitted.

As both a sound and electrical engineer I think most high end audio electronics is bullshit. If you know what you're doing a 50 cent opamp will give you results that are beyond what a human could identify in a double-randomized blind test. Same goes for comparing two rusty pieces of wire against highly pure copper speaker cables. For some reason audiophiles will use darn massive gold (or silver) RCA connectors instea…

> For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. Is there a reason why they don't just use digital audio everywhere and convert to analog as late as possible? Inside the speakers for example? I mean, digital audio is pretty much perfect. Why are analog audio signals still a thing? People actually pay tho…

> digital audio is pretty much perfect.

It can be. But standard Bluetooth connections for audio can be terrible. Streaming from the internet, that is digital, and there can be delays and gaps in the sound.

Re: Why do electronic components have such odd values? (2021)

#158

Post by galaxyLogic »

SAI_Peregrinus wrote: post #155
galaxyLogic wrote: post #124

Earlier quoted context omitted.

I see. I guess that's why high-end audio is so expensive

Ha! No, they're not using metrology resistors, just ripping people off.

High-end audio is a status-symbol. It shows that not only you are rich, but that you are also sophisticated.

But what happens if you don't like the music coming out of your stereo? No gold-plated connectors can cure that.

Re: Why do electronic components have such odd values? (2021)

#159

Post by mschuster91 »

atoav wrote: post #148
frabert wrote: post #134

Earlier quoted context omitted.

We're talking audiophiles, it's not like they're trying to cheap out.

Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays. I think this is more of a cultural divide than anything, with tradition being a big part of it. In the olden days balanced I/O had to be done using specialized transformers. Unless you got really expensive well wound ones these could degrade your signal significantly — that might've contributed to a bad rep in audiophile circles. But today you c…

> Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays.

Yeah but who outside of people already interested in DJing buys that kind of stuff. It just looks ugly, unlike your classic home theater setup.

Out of "looks decent (=passes the Spouse Acceptance Factor test)", "reasonably affordable" and "has decent quality", choose two... unless you got a partner accepting you literally putting up a 2m truss with lasers, movingheads and a strobe in your living room that could compete with a mid-range disco, and a 1.200W fogger on the ground. I'm lucky enough to have such a partner, but I'd say about 99% of people don't.

Re: Why do electronic components have such odd values? (2021)

#160

Post by galaxyLogic »

mschuster91 wrote: post #159
atoav wrote: post #148

Earlier quoted context omitted.

Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays. I think this is more of a cultural divide than anything, with tradition being a big part of it. In the olden days balanced I/O had to be done using specialized transformers. Unless you got really expensive well wound ones these could degrade your signal significantly — that might've contributed to a bad rep in audiophile circles. But today you c…

> Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays. Yeah but who outside of people already interested in DJing buys that kind of stuff. It just looks ugly, unlike your classic home theater setup. Out of "looks decent (=passes the Spouse Acceptance Factor test)", "reasonably affordable" and "has decent quality", choose two... unless you got a partner accepting you literally putting up a 2m truss…

There's something to it that the equipment should look beautiful in your living room, Bang and Olofssen -style. Music is beautiful, equipment playing it should be too. Or at least it enhances the experience.
Post reply on HN