Capacitors - I thought I knew them, but?

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
Hello All,
I recently bought one of those generic "component testers'" on Amazon or eBay, and I must say I am impressed. For less then 20 bucks this thing can identify and value test most passives, and show discreet semiconductor pinouts and generic family (NPN/PNP BJT, Triac, diode, etc.). I especially like the rapid test for capacitor value and overall condition. However, I felt like a bit of a dinosaur when I tested my first cap. I was told it was a 100nF cap with X % of VLOSS and had an ESR of x.xΩ.

I have been retired for about 7 years, spent the last 20 years of my career as a video systems engineer, and for 25 years before that I was a bench tech/field service eng./installer. My point is I have been away from "components" for quite a while, which may explain the questions coming next.

When did nano farad become a thing?

Most of my electronics training was through the U.S. Air Force, and we mostly talked in "puffs & muffs" (pF and µF). Of course there are now super capacitors, and we actually have caps measured in Farads, but this nF thing caught me off guard. And when did VLoss become popular? More importantly, are go/no go values for VLoss published anywhere (similar to ESR charts)? My last days as a bench tech introduced me to ESR. We often had to shotgun entire boards because those little SMD caps didn't have much of a life (has that improved at all?). One last comment - I used to be an electronic "tinkerer" in the late late '70's through about the mid '80's.

About a year ago I got the bug again and I am amazed at what is available. My home "lab" was stocked mostly with Heathkit stuff back in the day, but now DSO's, DDS generators and all manner of other goodies are now within the reach of the hobbyist. Add to that the Arduinos, Pi's and plethora of shields and software and this is a great hobby (with apologies to those of you that actually make a living at this stuff - I used to do that too, but find being a hobbyist is much more fun). Comments?
 

ebeowulf17

Joined Aug 12, 2014
3,274
nF is right there in the middle and, at least in theory, has always been there.

I'm a relative newcomer to electronics and it seems from my perspective like there are a few old patterns and habits that the industry still clings to which are not helpful.

The apparent avoidance of nF is one of them. With resistors, you generally choose whatever prefix (kilo, milli, Mega...) you need in order to make the value number require few, if any, decimal places or trailing zeros. This makes sense to me.

With capacitors on the other hand, I often see values described in bizarre ways, apparently to avoid certain units. Why would anyone label a capacitor as 0.027uF or 27000pF when they could just call it 27nF?

It's especial irksome to me because I have a meter that forces everything into nF and I buy parts that get labelled in anything but nF, so literally every time I double check a part I'm doing a unit conversion. Not a major problem, but it gets annoying after a while.
 

#12

Joined Nov 30, 2010
18,210
Nanofarads aren't any more special than kilometers. The world is getting smaller. People of many languages speak of these things. You just need to loosen up your vocabulary because you aren't working in a small shop any more. You're working in a world where people 10,000 miles away speak over a phone for no extra charge. In fact, this site has members in so many countries that I can't count that high, and some of the best are from strange places like Belarus. Can you find Belarus on a map? I only have a vague idea where to look. It must be somewhere around Russia. Wait. Does Russia still exist?

Got it? What is familiar to us old guys is irrelevant. Only the physics of it matter.
 

AnalogKid

Joined Aug 1, 2013
8,461
Like you, I was raised on uF and uuF. nF started creeping in about 30 years ago, and has been the standard for at least the last 10. It always has been the correct implementation of the SI rules, but you know those Americans...

As the universe of electronics (components, supply chain, manufacturing, whatever) has become more and more international, local idiosyncrasies have fallen away. As a tech writer, 1.0 nF is the only thing I use. But in my head I still see a small cap as a double-oh-one uF.

ak
 

OBW0549

Joined Mar 2, 2015
3,405
I remember when the darned things were still frequently referred to as "condensers." I also remember selenium rectifiers and copper oxide rectifiers. My Dad's parts drawer was full of 'em.

Capacitors were either microfarads or micromicrofarads. "Picofarads" didn't show up til later, and nanofarads later than that. I still call out cap values either in μF or pF, generally avoiding nF.

Old phart, old habits...
 

AnalogKid

Joined Aug 1, 2013
8,461
Did condensers and seleniums (silienia? sileniae?) in *old* TV's, but not copper oxide. Not long ago I had to explain to a young'n why resistor leads are so long.

ak
 

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
pF? You mean µµF, right?
I guess. I have never heard the term µµF before, but pF (picoFarad is 10 to the -12 power, so yes). Actually, I do recall µµF being used. It seems that dropped out of common use quite a while back though, right?
 
Last edited:

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
nF is right there in the middle and, at least in theory, has always been there.
Yes, I realize there was a "placeholder" (for lack of a better term), but I had never seen the term used as a common reference until the last few years. As I originally wrote, I am a dinosaur (I took Basic Electronics in the mid-1960's when "electron valves" were still in vogue).
I'm a relative newcomer to electronics and it seems from my perspective like there are a few old patterns and habits that the industry still clings to which are not helpful.
I totally agree. This happens in all aspects of our lives. Change comes with great difficulty. For example, I recall when I was a child (1950's) there was talk that the U.S. would join the rest of the world and use the Metric system (which makes much more sense to me) but that never happened. I am sure there were some good reasons (such as the costs of relabeling things, the unfamiliarity of the general public - can you imagine the confusion that would ensue over automobile speedometer indicators?), but it would make more sense (to me) if we used a 10 base system. Of course, these days perhaps a binary system would be better! Maybe change IS too confusing after all!
The apparent avoidance of nF is one of them. With resistors, you generally choose whatever prefix (kilo, milli, Mega...) you need in order to make the value number require few, if any, decimal places or trailing zeros. This makes sense to me.

With capacitors on the other hand, I often see values described in bizarre ways, apparently to avoid certain units. Why would anyone label a capacitor as 0.027uF or 27000pF when they could just call it 27nF?

It's especial irksome to me because I have a meter that forces everything into nF and I buy parts that get labelled in anything but nF, so literally every time I double check a part I'm doing a unit conversion. Not a major problem, but it gets annoying after a while.
I never did get the idea (as you point out) of labelling a "27000pF" cap, but .027µF made sense to me because I learned it that way. Had I learned 27nF, that would seem common to me. But since we now use nF, why do we still shy away from mF (milliFarad)? Perhaps that is because "mF" is also used for "microfarad???? So maybe the Greek alphabet should never have been used at all in science... this issue is wider than I thought when I posted this thread...
 

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
In Czech we still keep calling them condenser(s), or kondenzator(y) to be more precise.
Ha! I'm not sure exactly when we stopped calling them condensers here is the U.S., but I recall using that word often as a boy, particularly when referring to auto repair (replacing points and condenser). These days it seems condensers are restricted to air handling equipment. But this is another good example of "change for the good". I guess it would be interesting to trace the origins of the use of the term condenser (meaning electrical capacitor.
 

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
Nanofarads aren't any more special than kilometers. The world is getting smaller. People of many languages speak of these things. You just need to loosen up your vocabulary because you aren't working in a small shop any more. You're working in a world where people 10,000 miles away speak over a phone for no extra charge. In fact, this site has members in so many countries that I can't count that high, and some of the best are from strange places like Belarus. Can you find Belarus on a map? I only have a vague idea where to look. It must be somewhere around Russia. Wait. Does Russia still exist?

Got it? What is familiar to us old guys is irrelevant. Only the physics of it matter.
Funny you should mention Belarus. I recently played online 8-Ball with a player from Belarus. In fact I looked it up, and IIRC it was a part of the USSR. I realize we are now a global society, but my question was more about when the term "nF' became popular. Apparently I was napping at the time :)
 

ArakelTheDragon

Joined Nov 18, 2016
1,350
Hello All,
I recently bought one of those generic "component testers'" on Amazon or eBay, and I must say I am impressed. For less then 20 bucks this thing can identify and value test most passives, and show discreet semiconductor pinouts and generic family (NPN/PNP BJT, Triac, diode, etc.). I especially like the rapid test for capacitor value and overall condition. However, I felt like a bit of a dinosaur when I tested my first cap. I was told it was a 100nF cap with X % of VLOSS and had an ESR of x.xΩ.

I have been retired for about 7 years, spent the last 20 years of my career as a video systems engineer, and for 25 years before that I was a bench tech/field service eng./installer. My point is I have been away from "components" for quite a while, which may explain the questions coming next.

When did nano farad become a thing?

Most of my electronics training was through the U.S. Air Force, and we mostly talked in "puffs & muffs" (pF and µF). Of course there are now super capacitors, and we actually have caps measured in Farads, but this nF thing caught me off guard. And when did VLoss become popular? More importantly, are go/no go values for VLoss published anywhere (similar to ESR charts)? My last days as a bench tech introduced me to ESR. We often had to shotgun entire boards because those little SMD caps didn't have much of a life (has that improved at all?). One last comment - I used to be an electronic "tinkerer" in the late late '70's through about the mid '80's.

About a year ago I got the bug again and I am amazed at what is available. My home "lab" was stocked mostly with Heathkit stuff back in the day, but now DSO's, DDS generators and all manner of other goodies are now within the reach of the hobbyist. Add to that the Arduinos, Pi's and plethora of shields and software and this is a great hobby (with apologies to those of you that actually make a living at this stuff - I used to do that too, but find being a hobbyist is much more fun). Comments?
Please do not add Arduino! Arduino is more of a problem for hardware engineers, despite that's its something very good for software developers! One thing I hate is when the software developer comes and tells ne the PCB does not work! Then the strange air sounds from the mountg begin, as if I am not a good hardware engineer. Then I tell him reprogram it again and it suddenly starts working.......!
 

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
I see my original post has received many replies concerning the use of nF, but no one mentions VLoss. Are any of you familiar with the term (I know the meaning, but not the accepted limits in %)? I recently checked a bunch of "new old stock" (that was at least 30 years old) against some newer caps, and, as expected, the newer caps read well below 1% while the NOS caps were in the 3 to 4% range. I have read that electrolytics can be "reformed" be subjecting them to very low voltage and then gradually increasing the voltage until their rated voltage is applied. Has anyone tried this?
 

Thread Starter

MikeyChris

Joined Mar 10, 2018
31
It's been around as long as I can remember.
But when did it become common usage? I know it varies on location, and was used commonly more outside of the U.S. than it was used in the U.S., but it seems to now be used in test equipment as well as parts lists. I was just curious about the time frame the usage become popular.
 

OBW0549

Joined Mar 2, 2015
3,405
I see my original post has received many replies concerning the use of nF, but no one mentions VLoss. Are any of you familiar with the term (I know the meaning, but not the accepted limits in %)?
No. I don't recall seeing it in any capacitor specification, and I've been "doing electronics" since the late 1950's; and Googling the term "Vloss" gives only a few relevant hits, none of them informative. My impression is that it's probably a term invented by an amateur or amateurs, perhaps as a surrogate for the more conventional leakage current specification-- or some oddball amalgamation of leakage current and dissipation factor.

"Vloss"? Never heard of it.
 
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