why 4.7uf and not 5uf?

K

KD

Guest
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.
 
"KD" <k@nowhere.com> wrote in message
news:42e5ccdb$1@duster.adelaide.on.net...
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.
Click to expand...
Google is your friend. Look for preferred values.
 
"KD"
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.
Click to expand...

** 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 = 1.468

The 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

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3km208Fuv2fsU1@individual.net...
"KD"
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.


** 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 = 1.468

The 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
Click to expand...
 
This is were the E6 and E12 range comes in

e.g. E6 range has 6 values per decade



Jackie <Jackie@invalid.com.au> wrote in message
news:sMkFe.63062$oJ.4499@news-server.bigpond.net.au...
Phil,

Your knowledge amazes me!

Jackie

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3km208Fuv2fsU1@individual.net...
"KD"
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.


** 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 = 1.468

The 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
Click to expand...
 
"Jackie"
Phil,

Your knowledge amazes me!

Jackie
Click to expand...

** Yeah - so I can use a "scientific" pocket calculator.

BTW

Do YOU know what is the same as the 12th root of 2 ?


.............. Phil


"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3km208Fuv2fsU1@individual.net...

"KD"
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.


** 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 = 1.468

The 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
Click to expand...
 
I'm sure this is a loaded question! - No I don't

Jackie

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3km78qFv4123U1@individual.net...
"Jackie"
Phil,

Your knowledge amazes me!

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



"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3km208Fuv2fsU1@individual.net...

"KD"
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.


** 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 = 1.468

The 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
Click to expand...
 
Amazing!.. Thank you Phil!..

So why 6 steps in value value make up a decade? (Why 6?)

** 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 = 1.468

The 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
Click to expand...
 
"Posun Hurla"
Amazing!.. Thank you Phil!..

So why 6 steps in value value make up a decade? (Why 6?)
Click to expand...

** Think about tolerace percentages:

20 %, 10 % , 5 %, 2% etc.

6 steps makes good sense when the allowable tolerance is +/- 20 %.




........... Phil
 
On Tue, 26 Jul 2005 11:33:17 GMT, "Jackie" <Jackie@invalid.com.au>
wrote:

I'm sure this is a loaded question! - No I don't

Jackie
Click to expand...
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"

I'm sure this is a loaded question! - No I don't

Jackie

Maybe not, one answer I can think of is a semitone.
Click to expand...

** Spot on.


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.
Click to expand...

** 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 etc
 
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