what is going on with the multiples of 47 in caps?

[Gledison]

Hey guys, i was ordering some componenents for the nex three builds and realized that there are a lot of caps with values multiples of 47, 47u, 4,7n, 470p, etc...
There is something about this number or is just in my stupid head?

[kothoma]

Not sure about your question. Aren't there also many 100pF, 1nF, 10nF, 100nF, 1uF, 10uF,...?

As to why 4.7 and not 5.0, read up on E6/E12/E24 series or IEC 60063.
The idea is to space a decade logarithmically.
For example, for E12 you use the ratio 10^(1/12) = 1.21... between each of the 12 steps.

Why logarithmically? Not sure.
Maybe because tolerances are given in percentages.
Maybe because most of the time not absolute values are important but ratios.

[Gledison]

Not sure about your question. Aren't there also many 100pF, 1nF, 10nF, 100nF, 1uF, 10uF,...?

As to why 4.7 and not 5.0, read up on E6/E12/E24 series or IEC 60063.
The idea is to space a decade logarithmically.
For example, for E12 you use the ratio 10^(1/12) = 1,21... between each of the 12 steps.

Why logarithmically? Not sure.
Maybe because tolerances are given in percentages.
Maybe because most of the time not absolute values are important but ratios.

well, yeah, this kind of information. you are right, there is 1, 10 and 100, etc..
i was just intriged by the number 47 instead of 50 for example.
what do you mean with this :E6/E12/E24 series or IEC 60063?
thanks mate!

[Vallhagen]

i was just intriged by the number 47 instead of 50 for example.
what do you mean with this :E6/E12/E24 series or IEC 60063?
thanks mate!

E12 gives your 12 values / decade, E6 gives you 6 values / decade, E24 gives your 24...

E12, very common in our "diy world" is:
1
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
and then...
10
12
...

look at the values. In the middle somewhere you have your 4.7. Mathematically the values are "logarithmically spaced" which means the ratio (not the difference!) between two adjacent values are always the same. In the E12 case; 1.21.

Think about it; it would be inconvenient if it were arranged in another way than this.

Currencies are arranged this way too, but only by 3 values/decade. If we pay with pennies/dollars/gb Pounds / Euros/swedish kronor, the number on the coins and bills are 1, 2, 5, 10, 20, 50, 100, 200, 500... This is also logarithmically spacing (each value is "double the previous") but more "roughly rounded" for convenience. More "mathematically consistent" would be 10, 22, 47, 100, 220... which actually is the E3 series:)

...not sure if i added something useful here but... well i posted something
Cheerio

[Gledison]

i was just intriged by the number 47 instead of 50 for example.
what do you mean with this :E6/E12/E24 series or IEC 60063?
thanks mate!

E12 gives your 12 values / decade, E6 gives you 6 values / decade, E24 gives your 24...

E12, very common in our "diy world" is:
1
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
and then...
10
12
...

look at the values. In the middle somewhere you have your 4.7. Mathematically the values are "logarithmically spaced" which means the ratio (not the difference!) between two adjacent values are always the same. In the E12 case; 1.21.

Think about it; it would be inconvenient if it were arranged in another way than this.

Currencies are arranged this way too, but only by 3 values/decade. If we pay with pennies/dollars/gb Pounds / Euros/swedish kronor, the number on the coins and bills are 1, 2, 5, 10, 20, 50, 100, 200, 500... This is also logarithmically spacing (each value is "double the previous") but more "roughly rounded" for convenience. More "mathematically consistent" would be 10, 22, 47, 100, 220... which actually is the E3 series:)

...not sure if i added something useful here but... well i posted something
Cheerio

ohhhh yeas sir! that  explains what i was not understanding at all!
thanks a lot!!

[kothoma]

...read up on E6/E12/E24 series or IEC 60063.

...what do you mean with this :E6/E12/E24 series or IEC 60063?

You really need to find out about google http://www.google.de/search?q=e6+e12+e24+IEC+60063

[kothoma]

Currencies are arranged this way too, but only by 3 values/decade. If we pay with pennies/dollars/gb Pounds / Euros/swedish kronor, the number on the coins and bills are 1, 2, 5, 10, 20, 50, 100, 200, 500... This is also logarithmically spacing (each value is "double the previous") but more "roughly rounded" for convenience.

Yeah, nice observation. Never thought about it this way.

More "mathematically consistent" would be 10, 22, 47, 100, 220... which actually is the E3 series:)

Well, really mathematically consistent would be
E3: 10 22 46(!) 100
E6:  10 15 22 32(!) 46(!) 68 100
and so on

[ch1naski]

Oh, it's math. Or as I like to call it, BLACK MAGIC.


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[kothoma]

Oh, it's math. Or as I like to call it, BLACK MAGIC.

Yeah, the only magic that works every time.

[ch1naski]

I only slightly understand what you guys are saying. I'm a high school drop out, so not much math knowledge. I do understand the meaning of logarithm, but not as it pertains to electronic signals and why it's used for cap values instead of values in base 10, or in a linear arrangement.

I don't even know if I said that right.....lol.

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[kothoma]

I only slightly understand what you guys are saying. I'm a high school drop out, so not much math knowledge. I do understand the meaning of logarithm, but not as it pertains to electronic signals and why it's used for cap values instead of values in base 10, or in a linear arrangement.

I don't even know if I said that right.....lol.

You know that logarithmic is inverse to exponential.

Some things just aren't linear. Our ears for example. That's why we have audio taper pots and these funny dB.

Or sometimes not differences (lin) are important but ratios (log). Think of gain. It often is calculated by R2/R1. The absolute values of R1 and R2 aren't relevant in this formula. Only the ratio.

Dividing something linearly you just divide: 100/12 = 8.333...
Now you just add (or multiply with a whole number) and get  0, 8.333, 16.33, 25, ..., 100

Dividing something logarithmically into n steps you need the n-th root of what you want to divide: 10^(1/12) = 1.2115...  (why? think about it like this: 12 times multiplied with itself gives (10^(1/12))^12 = 10).
Now you just multiply one step with this factor to get to the next and get 10, 12.11..., 14.67..., 17.78..., ..., 100.

So the values in E12 rise in steps of 21%.

Edit. Also think about how the octave is divided into 12 semitones, or (a bit more complicated) how half a string length is divided into 12 frets. Left as an exercise for the reader...

[billstein]

Oh, it's math. Or as I like to call it, BLACK MAGIC.


Sent from my SPH-L710 using Tapatalk

I think you understand math just fine my friend. I see it in your signature. ONE louder.

[DutchMF]

And it's not only electronic components. The valves we use to regulate flow in piping (I work in HVAC) are spaced according to the E6 series, with the number indicating how much medium flows through the valve when a certain pressure is applied......... Sorry to bore you with this.....

Paul

[Gledison]

Currencies are arranged this way too, but only by 3 values/decade. If we pay with pennies/dollars/gb Pounds / Euros/swedish kronor, the number on the coins and bills are 1, 2, 5, 10, 20, 50, 100, 200, 500... This is also logarithmically spacing (each value is "double the previous") but more "roughly rounded" for convenience.

Yeah, nice observation. Never thought about is this way.

More "mathematically consistent" would be 10, 22, 47, 100, 220... which actually is the E3 series:)

Well, really mathematically consistent would be
E3: 10 22 46(!) 100
E6:  10 15 22 32(!) 46(!) 68 100
and so on

you see! thats why i didnt want to read whatever i find on Google! i think we all know how to search there. I wanted to open a discussion that is very important for the noobs like me. morever, having the focus on pedal building. It seems that i got what i want, a nice discussion with very nice explanations from the experienced people.

[Gledison]

And it's not only electronic components. The valves we use to regulate flow in piping (I work in HVAC) are spaced according to the E6 series, with the number indicating how much medium flows through the valve when a certain pressure is applied......... Sorry to bore you with this.....

Paul

Not bothering at All Paul. I remembered to read a very nice explanation from Brian correlating electrons flow with water flow on pipes and how resistors and capacitors could be related to real life situations...so! I think for those of us that are not electric/tronic engineers sometimes is much easier to understand with analogies, at lest for me. There is even a thread where someone compare the populated PCBs with little cities......This pedal building stuff is just Amaaaaaaazing, im learning every day something new! thanks to all fo you!