Hi guys,
A curious question someone here might be able to answer...
why is that there is are 4.7uf or 2.2uf or 1.6uf etc values of capacitance and not rounded values of say 5uf, 2uf, etc?
why those values 47, 22, 16, etc....?? is there something special about them??
love to hear an reason for using those figures.
Google is your friend. Look for preferred values.
"KD"
** When 6 steps in value make up a decade ( ie 10 times) increase in value.So each step needs to be the 6th root of 10.
10 exp 0.1666 = 1.468The exact steps then are:
1, 1.47, 2.15, 3.16, 4.64, 6.81, 10.Rounded to :
1, 1.5, 2.2, 3.3, 4.7, 6.8, 10.For 12 steps, the number are:
1, 1.21, 1.47, 1.78, 2.15, 2.61, 3.16, 3.83, 4.64, 5.62, 6.81, 8.25, 10.......... Phil
Phil,
Your knowledge amazes me!
Jackie
capacitance
value.
This is were the E6 and E12 range comes in
e.g. E6 range has 6 values per decade
Your knowledge amazes me!
Jackie
capacitance
value.
"Jackie"
** Yeah - so I can use a "scientific" pocket calculator.BTW
Do YOU know what is the same as the 12th root of 2 ?
............. Phil
I'm sure this is a loaded question! - No I don't
Jackie
about
6.81,Amazing!.. Thank you Phil!..
So why 6 steps in value value make up a decade? (Why 6?)
"Posun Hurla"
** Think about tolerace percentages: 20 %, 10 % , 5 %, 2% etc. 6 steps makes good sense when the allowable tolerance is +/- 20 %........... Phil
Maybe not, one answer I can think of is a semitone. A semitone is the difference in pitch between each fret on the guitar or practically any musical instument that is tuned to what is called a "chromatic scale" (aka equal tempered 12 note scale). Musical tones are measured in semitones and octaves where as electrical component values are normally measured in decades and as Phil pointed out.
regards, Johnny.
"Johnny" "Jackie"
** Spot on.** That is the connection.
Eg: a " third octave" audio equaliser has steps that are governed by the
3rd root of 2.......... Phil
when i was a lad,,,,,,,, 2.5uF 5uF 7.5uF was the go. with electro caps near enough is good enough anyway.
E3 are the most used values ie; 3 values per decade:
1, 2.2, 4.7, 10, 22, 47 etcHave something to add? Share your thoughts — no account required.
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