5 ms·

The “coverage” explanation given by the top answer doesn’t make a whole lot of sense. With the manufacturing tolerances involved (especially historically when t

The “coverage” explanation given by the top answer doesn’t make a whole lot of sense. With the manufacturing tolerances involved (especially historically when those values were chosen!) the idea that 22 and 47 gives more useful combinations than 22 and 46 is numerology, not engineering. Wikipedia only says that the deviation is for “unknown historical reasons”. Maybe a deep explanation doesn’t exist, and it’s a simple historical error that was propagated?

danbruc 4y ago
Similarly I find the no odd numbers argument unconvincing, again because of the tolerances and also because placing two of the resistors in parallel yields odd values for 10 and 22 and almost 15 (14.9855) for 22 and 47.
- adql 4y ago
  Also you can just use one magnitude lower resistor... 10 isn't odd but 1 is. Honestly the explanation looks like someone tried to reverse-engineer a mistake into logic.
YetAnotherNick 4y ago
But there is no reason why 0 tolerance resistor couldn't exist or even being very useful for certain application like voltmeter.
- Gordonjcp 4y ago
  If you want 0% tolerance, you can hand-match. No-one needs 0% tolerance.
  - atoav 4y ago
    Sure, you can handmatch. If the thermal radiation of your hands wouldn't affect the measurement.
    - Gordonjcp 4y ago
      This is actually a real problem with semiconductors. I often need carefully matched sets of transistors and diodes, and a quick and easy way to get them "good enough" is just to measure either a diode or the B-E junction of the transistor with a multimeter in "diode check" mode. I pin the paper strip to a piece of wood and let the temperature stabilise for about half an hour before I start, and only touch the component with the meter probes. You can try this yourself. With any given 1N4148 you'll see the Vf indication on the meter change as the microscopic current warms the junction up a tiny bit. If the room (and thus the diode) is fairly cold, it can detect the heat from your finger at about 1cm away.
- Melkman 4y ago
  The reason you can not build a 0% tolerance resistor is the laws of physics. A very high precision resistor can certainly be build but it will never be perfect. Increasing precision has a cost to it. For normal resistors the shape and thickness of the film of resisting material is calculated and the tolerance is mainly dictated by the precision of the manufacturing process. Increasing this precision of the process adds cost. High precision resistors can be trimmed to specification. When you manufacture the resistor with a lower resistance you can use a laser to trim some of the resistive material away. This is an extra step and adds extra cost. While this can be very precise you are limited to what you can measure and there is a limit to that. Also precision is limited by environmental factors like heat, humidity and aging.
  - adql 4y ago
    That's also how many higher end analog chips are made, just blast it with laser till it fits tolerance. Making a bunch of chips in less precise process then trimming them chip by chip ends up cheaper than going to more expensive processes.
  - YetAnotherNick 4y ago
    We are saying the same thing. For most applications, 5% tolerance is fine if could be cheaper. But for some applications it is worth the extra cost.
    - klodolph 4y ago
      It sounded like you were saying that a 0 tolerance resistor would be worth the extra cost, and the reply is pointing out that a 0 tolerance resistor is not actually possible anyway, and as you approach 0, the cost increases beyond whatever your limit is.
      - JKCalhoun 4y ago
        It would seem pretty pointless to try to nail the resistor to within 0% tolerance when the solder bridges, wire that connects them to the circuit will have resistance.
- deleted 4y ago
  [deleted]
- deelowe 4y ago
  > But there is no reason why 0 tolerance resistor couldn't exist I think the laws of physics is a pretty good reason.
pclmulqdq 4y ago
Ultra-precise resistor values have been possible for as long as there have been good meters. It turns out that's a very long time ago. The numerology makes a lot of sense if you are working with 0.1% tolerance parts. Lower tolerances have actually gotten more popular as electronics have become more cost-sensitive.
- michaelt 4y ago
  Possible, sure, but isn't the origin of the E12 series, as opposed to using e.g. the Renard R10 series, for specifying ±10% precision parts? 1 ±10% is 0.9 to 1.1 1.2 ±10% is 1.08 to 1.32 1.5 ±10% is 1.35 to 1.65 1.8 ±10% is 1.62 to 1.98 2.2 ±10% is 1.98 to 2.42 And so on.
- adql 4y ago
  > Ultra-precise resistor values have been possible for as long as there have been good meters. It turns out that's a very long time ago. It's not about metering but stability of the resulting value. 1% or 0.1% doesn't do you much good if few degree temperature change gets it out of spec. Now temperature coefficent is an additional spec on the spec sheet but by definition you kinda need low drift to go in pair with high precision > The numerology makes a lot of sense if you are working with 0.1% tolerance parts. Lower tolerances have actually gotten more popular as electronics have become more cost-sensitive. Lower tolerances have just become cheap. Back when I was a kid there was significant difference in price between 1% and 5% resistors. Now they cost basically same (for low power ones at least) so why not ? [1] You also don't really need that many precision parts in the first palce. Where before in say a power amplifier you had say an analog preamp driving power IC (or outright discrete power amplifier) you had to have a bunch of precise resistors (or someone tweaking a pot on the production line) to keep the gain same in both tracks. Now you just slap a D-class chip that takes line in and outputs power and you're done, and the few % variance in power supply caps or output filter doesn't matter much. * [1] https://eu.mouser.com/c/passive-components/resistors/?case%20code%20-%20in=0603&resistance=1%20kOhms&sort=pricing https://eu.mouser.com/c/passive-components/resistors/?case%2...
  - pclmulqdq 4y ago
csours 4y ago
As I read it, rationalization is one of the core reasons.
layer8 4y ago
Note that the linked document https://www.govinfo.gov/content/pkg/GOVPUB-C13-f5fea679df4c3a1c2e3e1dd63488707c/pdf/GOVPUB-C13-f5fea679df4c3a1c2e3e1dd63488707c.pdf https://www.govinfo.gov/content/pkg/GOVPUB-C13-f5fea679df4c3... doesn’t just apply to resistors or electrical components. It is a general framework for deriving “preferred” numbers.
simne 4y ago
Main reason are costs for mass production, and nuances of technology, that electronic components usually made in very huge batches, then distributed to distribution network and lie on storage up to tens years. So manufacturers made series of agreements, like "in 2020-2025 make e3; in 2025-2030 make e12".
- simne 4y ago
  Expensive high precision parts, are not in this scheme, they allocated by direct requests, like Toshiba manufacture high-end transistors, and order for them high-end resistors with some exact value.

danbruc 4y ago

Similarly I find the no odd numbers argument unconvincing, again because of the tolerances and also because placing two of the resistors in parallel yields odd values for 10 and 22 and almost 15 (14.9855) for 22 and 47.

adql 4y ago
Also you can just use one magnitude lower resistor... 10 isn't odd but 1 is. Honestly the explanation looks like someone tried to reverse-engineer a mistake into logic.

YetAnotherNick 4y ago

But there is no reason why 0 tolerance resistor couldn't exist or even being very useful for certain application like voltmeter.

Gordonjcp 4y ago
If you want 0% tolerance, you can hand-match. No-one needs 0% tolerance.
- atoav 4y ago
  Sure, you can handmatch. If the thermal radiation of your hands wouldn't affect the measurement.
  - Gordonjcp 4y ago
    This is actually a real problem with semiconductors. I often need carefully matched sets of transistors and diodes, and a quick and easy way to get them "good enough" is just to measure either a diode or the B-E junction of the transistor with a multimeter in "diode check" mode. I pin the paper strip to a piece of wood and let the temperature stabilise for about half an hour before I start, and only touch the component with the meter probes. You can try this yourself. With any given 1N4148 you'll see the Vf indication on the meter change as the microscopic current warms the junction up a tiny bit. If the room (and thus the diode) is fairly cold, it can detect the heat from your finger at about 1cm away.
Melkman 4y ago
The reason you can not build a 0% tolerance resistor is the laws of physics. A very high precision resistor can certainly be build but it will never be perfect. Increasing precision has a cost to it. For normal resistors the shape and thickness of the film of resisting material is calculated and the tolerance is mainly dictated by the precision of the manufacturing process. Increasing this precision of the process adds cost. High precision resistors can be trimmed to specification. When you manufacture the resistor with a lower resistance you can use a laser to trim some of the resistive material away. This is an extra step and adds extra cost. While this can be very precise you are limited to what you can measure and there is a limit to that. Also precision is limited by environmental factors like heat, humidity and aging.
- adql 4y ago
  That's also how many higher end analog chips are made, just blast it with laser till it fits tolerance. Making a bunch of chips in less precise process then trimming them chip by chip ends up cheaper than going to more expensive processes.
- YetAnotherNick 4y ago
  We are saying the same thing. For most applications, 5% tolerance is fine if could be cheaper. But for some applications it is worth the extra cost.
  - klodolph 4y ago
    It sounded like you were saying that a 0 tolerance resistor would be worth the extra cost, and the reply is pointing out that a 0 tolerance resistor is not actually possible anyway, and as you approach 0, the cost increases beyond whatever your limit is.
    - JKCalhoun 4y ago
      It would seem pretty pointless to try to nail the resistor to within 0% tolerance when the solder bridges, wire that connects them to the circuit will have resistance.
deleted 4y ago
[deleted]
deelowe 4y ago
> But there is no reason why 0 tolerance resistor couldn't exist I think the laws of physics is a pretty good reason.

pclmulqdq 4y ago

Ultra-precise resistor values have been possible for as long as there have been good meters. It turns out that's a very long time ago. The numerology makes a lot of sense if you are working with 0.1% tolerance parts. Lower tolerances have actually gotten more popular as electronics have become more cost-sensitive.

michaelt 4y ago
Possible, sure, but isn't the origin of the E12 series, as opposed to using e.g. the Renard R10 series, for specifying ±10% precision parts? 1 ±10% is 0.9 to 1.1 1.2 ±10% is 1.08 to 1.32 1.5 ±10% is 1.35 to 1.65 1.8 ±10% is 1.62 to 1.98 2.2 ±10% is 1.98 to 2.42 And so on.
adql 4y ago
> Ultra-precise resistor values have been possible for as long as there have been good meters. It turns out that's a very long time ago. It's not about metering but stability of the resulting value. 1% or 0.1% doesn't do you much good if few degree temperature change gets it out of spec. Now temperature coefficent is an additional spec on the spec sheet but by definition you kinda need low drift to go in pair with high precision > The numerology makes a lot of sense if you are working with 0.1% tolerance parts. Lower tolerances have actually gotten more popular as electronics have become more cost-sensitive. Lower tolerances have just become cheap. Back when I was a kid there was significant difference in price between 1% and 5% resistors. Now they cost basically same (for low power ones at least) so why not ? [1] You also don't really need that many precision parts in the first palce. Where before in say a power amplifier you had say an analog preamp driving power IC (or outright discrete power amplifier) you had to have a bunch of precise resistors (or someone tweaking a pot on the production line) to keep the gain same in both tracks. Now you just slap a D-class chip that takes line in and outputs power and you're done, and the few % variance in power supply caps or output filter doesn't matter much. * [1] https://eu.mouser.com/c/passive-components/resistors/?case%20code%20-%20in=0603&resistance=1%20kOhms&sort=pricing https://eu.mouser.com/c/passive-components/resistors/?case%2...
- pclmulqdq 4y ago

csours 4y ago

As I read it, rationalization is one of the core reasons.

layer8 4y ago

Note that the linked document https://www.govinfo.gov/content/pkg/GOVPUB-C13-f5fea679df4c3a1c2e3e1dd63488707c/pdf/GOVPUB-C13-f5fea679df4c3a1c2e3e1dd63488707c.pdf https://www.govinfo.gov/content/pkg/GOVPUB-C13-f5fea679df4c3... doesn’t just apply to resistors or electrical components. It is a general framework for deriving “preferred” numbers.

simne 4y ago

Main reason are costs for mass production, and nuances of technology, that electronic components usually made in very huge batches, then distributed to distribution network and lie on storage up to tens years. So manufacturers made series of agreements, like "in 2020-2025 make e3; in 2025-2030 make e12".

simne 4y ago
Expensive high precision parts, are not in this scheme, they allocated by direct requests, like Toshiba manufacture high-end transistors, and order for them high-end resistors with some exact value.