Author Topic: uSupply - 100nF vs 0.1uF  (Read 4582 times)

0 Members and 1 Guest are viewing this topic.

Offline poindexterity

  • Contributor
  • Posts: 10
  • Country: ca
uSupply - 100nF vs 0.1uF
« on: July 23, 2016, 12:06:42 am »
http://www.eevblog.com/files/uSupplyBenchRevC.pdf

In some places (the PWM filter), Dave uses 0.1uF denoted caps.  In others (ADC input, op amp V+) he uses 100nF.

Why does he use both?  Is it to denote different types of capacitor?  I know the op amp (decoupling?) filters should be ceramic, but don't know what type of nonpolarized cap to use in the filter.  I would assume that it's Tantalum, but I don't really know.
 

Offline ebclr

  • Super Contributor
  • ***
  • Posts: 1620
  • Country: 00
Re: uSupply - 100nF vs 0.1uF
« Reply #1 on: July 23, 2016, 12:09:57 am »
100nF = 0.1uF = 100Kpf

Everything is exactly the same value
 

Offline poindexterity

  • Contributor
  • Posts: 10
  • Country: ca
Re: uSupply - 100nF vs 0.1uF
« Reply #2 on: July 23, 2016, 12:11:30 am »
Yes, I'm aware of SI notation.  ;)

My question is this: Why does Dave use both notations on the same schematic?  Why not use 0.1uF everywhere or 100nF everywhere?
 

Offline ebclr

  • Super Contributor
  • ***
  • Posts: 1620
  • Country: 00
Re: uSupply - 100nF vs 0.1uF
« Reply #3 on: July 23, 2016, 12:21:43 am »
It's because he is Australian
 

Offline poindexterity

  • Contributor
  • Posts: 10
  • Country: ca
Re: uSupply - 100nF vs 0.1uF
« Reply #4 on: July 23, 2016, 12:48:04 am »
So you're implying that he doesn't intend anything by the different markings.  I can use the same ceramic capacitors in all places that are nonpolarized 0.1uF and 100nF, is that correct?
 

Offline ebclr

  • Super Contributor
  • ***
  • Posts: 1620
  • Country: 00
Re: uSupply - 100nF vs 0.1uF
« Reply #5 on: July 23, 2016, 01:17:03 am »
No, polarized capacitor normally have a + on one side off the schematic,

https://commons.wikimedia.org/wiki/File:Polarized_capacitor_symbol.png
 

Offline poindexterity

  • Contributor
  • Posts: 10
  • Country: ca
Re: uSupply - 100nF vs 0.1uF
« Reply #6 on: July 23, 2016, 01:46:22 am »
I don't mean to nitpick, but your responses consistently miss the mark.  I asked:

I can use the same ceramic capacitors in all places that are nonpolarized 0.1uF and 100nF, is that correct?

And you responded:

No, polarized capacitor normally have a + on one side off the schematic,

Can you explain how your response answers my question?
 

Offline ZeTeX

  • Frequent Contributor
  • **
  • Posts: 589
  • Country: il
  • When in doubt, add more flux.
Re: uSupply - 100nF vs 0.1uF
« Reply #7 on: July 23, 2016, 01:51:47 am »
So you're implying that he doesn't intend anything by the different markings.  I can use the same ceramic capacitors in all places that are nonpolarized 0.1uF and 100nF, is that correct?
Yes

 
The following users thanked this post: poindexterity

Online T3sl4co1l

  • Super Contributor
  • ***
  • Posts: 11299
  • Country: us
  • Expert, Analog Electronics, PCB Layout, EMC
    • Seven Transistor Labs
Re: uSupply - 100nF vs 0.1uF
« Reply #8 on: July 23, 2016, 10:45:26 am »
Laziness. :)

I seek consistency over laziness, so I actively search out any labels that are inconsistent.

I typically label capacitors as:
0.1uF and up
1-99nF
1-999pF

I do not place "0.01uF" and "10nF" simultaneously in the same design.  That would be silly! ;)

Similarly, I have a preferred system for resistors (for which, a thousand is always lowercase 'k', because it's kilo, not Kelvin!) and inductors.

By "typically", I allow for differences between projects, especially when I'm maintaining an existing design.  Someone called a Y1 cap "2200pF"?  Oh well, just make sure the rest do.

Tim
Seven Transistor Labs, LLC
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
 
The following users thanked this post: ludzinc

Online Rerouter

  • Super Contributor
  • ***
  • Posts: 3370
  • Country: au
  • Question Everything... Except This Statement
Re: uSupply - 100nF vs 0.1uF
« Reply #9 on: July 23, 2016, 12:07:46 pm »
for myself i am an engineering notation kind, so 0-999pF, 0-999nF, 0-X uF, so yes i will call a 2200uF cap 2200uF not 2.2mF,
 
The following users thanked this post: mrpackethead

Offline ebclr

  • Super Contributor
  • ***
  • Posts: 1620
  • Country: 00
Re: uSupply - 100nF vs 0.1uF
« Reply #10 on: July 23, 2016, 12:14:27 pm »
Just because the capacitor have the same value, does not mean they are the same capacitor, this is why you need to make a bom list, some capacitor are optimized to have a good relation volume / capacitance , others to have  low esr, others to have good temperature performance, it's a real science to use the right capacitor at the right place. I doubt Dave take care to have this defined at schematic level since is impossible to differentiate all kinds off capacitor only by the symbol / value notation
 

Offline derGoldstein

  • Regular Contributor
  • *
  • Posts: 146
  • Country: il
    • RapidFlux
Re: uSupply - 100nF vs 0.1uF
« Reply #11 on: July 23, 2016, 02:10:08 pm »
I can think of one example that I've seen a very long time ago for this type of inconsistency, and which I'll occasionally use myself: "0.1uF" means it's a bypass cap, "100nF" means that it's anything else. I'm not at all saying that this is why it's this way here, just that it's just one reason that I've seen it done.

When there are a lot of ICs on a board communicating using SPI or I2C, mixed in with all sorts of comparators and op-amps, you're going to have a ton of small capacitors, half of them probably bypass caps. To make the schematic a bit easier to read, I'd put "0.1uF" for all of the bypass caps, because that's an explicit exception to how I'd normally write that value -- "100nF". That way when I come back to that schematic a couple of years later and try to figure out why everything is laid out the way it is, I can "ignore" the bypass caps. Anyone else looking at the schematic might be annoyed at the inconsistency, but it won't interfere with them reading it.
But that's just me.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 26642
  • Country: au
    • EEVblog
Re: uSupply - 100nF vs 0.1uF
« Reply #12 on: July 23, 2016, 05:42:16 pm »
My question is this: Why does Dave use both notations on the same schematic?  Why not use 0.1uF everywhere or 100nF everywhere?

I might have copied stuff from other older schematics.
 

Offline Brumby

  • Supporter
  • ****
  • Posts: 7434
  • Country: au
Re: uSupply - 100nF vs 0.1uF
« Reply #13 on: July 23, 2016, 06:33:07 pm »
I can't say mixing up 0.1uF and 100nF on a circuit has ever worried me.  I've even coped with 0.22uF and 220nF.  ;D
 

Offline blueskull

  • Supporter
  • ****
  • Posts: 9946
  • Country: cn
  • Power Electronics Guy
Re: uSupply - 100nF vs 0.1uF
« Reply #14 on: July 23, 2016, 06:37:24 pm »
I can't say mixing up 0.1uF and 100nF on a circuit has ever worried me.  I've even coped with 0.22uF and 220nF.  ;D

I do not even put values on schematics. I only put them on final assembly sheets and BOM if there is one.
I know it is not a good practice, but that's how I do things.
SIGSEGV is inevitable if you try to talk more than you know. If I say gibberish, keep in mind that my license plate is SIGSEGV.
 

Online mrpackethead

  • Super Contributor
  • ***
  • Posts: 1670
  • Country: nz
Re: uSupply - 100nF vs 0.1uF
« Reply #15 on: July 23, 2016, 07:30:42 pm »
for myself i am an engineering notation kind, so 0-999pF, 0-999nF, 0-X uF, so yes i will call a 2200uF cap 2200uF not 2.2mF,

yes, i use this as well..    my notation would look like

1p2F  11pF 82pF  680pF
1nF   8n2F
47uF

Resistors are tricky, because i do something bad..   0R012 12R2  1k56   1M56
 

Offline Brumby

  • Supporter
  • ****
  • Posts: 7434
  • Country: au
Re: uSupply - 100nF vs 0.1uF
« Reply #16 on: July 23, 2016, 10:58:54 pm »
I can read 6k8 - but I write 6.8k.  Old fashioned, but explicit.
 

Offline timb

  • Super Contributor
  • ***
  • Posts: 2528
  • Country: us
  • Pretentiously Posting Polysyllabic Prose
    • timb.us
Re: uSupply - 100nF vs 0.1uF
« Reply #17 on: July 23, 2016, 11:46:38 pm »
I can read 6k8 - but I write 6.8k.  Old fashioned, but explicit.

I was brought up with the 6.8k notation, but eventually switched to 6k8, as it's much, much clearer to read. Decimal points can get lost or misread easily. This is also why I use 100n instead of 0.1u almost exclusively.
Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 

Offline StillTrying

  • Super Contributor
  • ***
  • Posts: 1389
  • Country: gb
  • 100% Brand New and High Quality, in theory.
Re: uSupply - 100nF vs 0.1uF
« Reply #18 on: July 24, 2016, 12:40:46 am »
I use them all, 0.22u, 220n, and even 0u22, 2R2, 22R, 22K 2K2.

I might have copied stuff from other older schematics.
Did you copy U12A LM358, I think it's a mistake and it's inputs and output won't work up there.

Offline klunkerbus

  • Supporter
  • ****
  • Posts: 136
  • Country: us
  • Electrical Engineer (retired early)
Re: uSupply - 100nF vs 0.1uF
« Reply #19 on: July 24, 2016, 12:55:29 am »
At least the days of capacitors being labeled as uuF instead of pF seem to be behind us now...
 

Offline Seekonk

  • Super Contributor
  • ***
  • Posts: 1731
  • Country: us
Re: uSupply - 100nF vs 0.1uF
« Reply #20 on: July 24, 2016, 04:32:30 am »
I drew a quick schematic for a beginner on a board and noted a resistor should be 10-22K.  He came back the next day all pissed after it blew up in his face.  He said just to be safe he used a 15 ohm. To be safe I no longer write it that way.   Still not sure who was grammatically correct.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf